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Using sizeof(bool) is considered poor form for various reasons and
sparse warns us of that. Correct by changing type from bool to u8.
Signed-off-by: Matthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: Manoj N. Kumar <manoj@linux.vnet.ibm.com>
Reviewed-by: Brian King <brking@linux.vnet.ibm.com>
Reviewed-by: Daniel Axtens <dja@axtens.net>
Reviewed-by: Tomas Henzl <thenzl@redhat.com>
Signed-off-by: James Bottomley <JBottomley@Odin.com>
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If the same virtual LUN is accessed over multiple cards, only accesses
made over the first card will be valid. Accesses made over the second
card will go to the wrong LUN causing data corruption.
This is because the global LUN's mode word was being used to determine
whether the LUN table for that card needs to be programmed. The mode
word would be setup by the first card, causing the LUN table for the
second card to not be programmed.
By unconditionally initializing the LUN table (not depending on the
mode word), the problem is avoided.
Signed-off-by: Matthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: Manoj N. Kumar <manoj@linux.vnet.ibm.com>
Reviewed-by: Brian King <brking@linux.vnet.ibm.com>
Reviewed-by: Tomas Henzl <thenzl@redhat.com>
Signed-off-by: James Bottomley <JBottomley@Odin.com>
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When a LUN is removed, the sdev that is associated with the LUN
remains intact until its reference count drops to 0. In order
to prevent an sdev from being removed while a context is still
associated with it, obtain an additional reference per-context
for each LUN attached to the context.
This resolves a potential Oops in the release handler when a
dealing with a LUN that has already been removed.
Signed-off-by: Matthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: Manoj N. Kumar <manoj@linux.vnet.ibm.com>
Reviewed-by: Brian King <brking@linux.vnet.ibm.com>
Reviewed-by: Tomas Henzl <thenzl@redhat.com>
Signed-off-by: James Bottomley <JBottomley@Odin.com>
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The timeout value for read capacity is too small. Certain devices
may take longer to respond and thus the command may prematurely
timeout. Additionally the literal used for the timeout is stale.
Update the timeout to 30 seconds (matches the value used in sd.c)
and rework the timeout literal to a more appropriate description.
Signed-off-by: Matthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: Manoj N. Kumar <manoj@linux.vnet.ibm.com>
Reviewed-by: Brian King <brking@linux.vnet.ibm.com>
Reviewed-by: Tomas Henzl <thenzl@redhat.com>
Signed-off-by: James Bottomley <JBottomley@Odin.com>
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Magic numbers are not meaningful and can create confusion. As a
remedy, replace them with descriptive literals.
Replace 512 with literal MAX_SECTOR_UNIT.
Replace 5 with literal CMD_RETRIES.
Signed-off-by: Matthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: Manoj N. Kumar <manoj@linux.vnet.ibm.com>
Reviewed-by: Brian King <brking@linux.vnet.ibm.com>
Reviewed-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Reviewed-by: Tomas Henzl <thenzl@redhat.com>
Signed-off-by: James Bottomley <JBottomley@Odin.com>
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If two concurrent MANAGE_LUN ioctls are issued with the same
WWID parameter, it would result in an incorrect value of port_sel.
This is because port_sel is modified without any locks being
held. If the first caller stalls after the return from
find_and_create_lun(), the value of port_sel will be set
incorrectly to indicate a single port, though in this case
it should have been set to both ports.
To fix, use the global mutex to serialize the lookup of the
WWID and the subsequent modification of port_sel.
Signed-off-by: Matthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: Manoj N. Kumar <manoj@linux.vnet.ibm.com>
Reviewed-by: Brian King <brking@linux.vnet.ibm.com>
Reviewed-by: Tomas Henzl <thenzl@redhat.com>
Signed-off-by: James Bottomley <JBottomley@Odin.com>
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The "compatible" matching algorithm used for looking up old-style
blacklist entries in a scsi_dev_info_list is buggy. The core of the
algorithm looks like this:
if (memcmp(devinfo->vendor, vendor,
min(max, strlen(devinfo->vendor))))
/* not a match */
where max is the length of the device's vendor string after leading
spaces have been removed but trailing spaces have not. Because of the
min() computation, either entry could be a proper substring of the
other and the code would still think that they match.
In the case originally reported, the device's vendor and product
strings were "Inateck " and " ". These matched against
the following entry in the global device list:
{"", "Scanner", "1.80", BLIST_NOLUN}
because "" is a substring of "Inateck " and "" (the result of removing
leading spaces from the device's product string) is a substring of
"Scanner". The mistaken match prevented the system from scanning and
finding the device's second Logical Unit.
This patch fixes the problem by making two changes. First, the code
for leading-space removal is hoisted out of the loop. (This means it
will sometimes run unnecessarily, but since a large percentage of all
lookups involve the "compatible" entries in global device list, this
should be an overall improvement.) Second and more importantly, the
patch removes trailing spaces and adds a check to verify that the two
resulting strings are exactly the same length. This prevents matches
where one entry is a proper substring of the other.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reported-by: Giulio Bernardi <ugilio@gmail.com>
Tested-by: Giulio Bernardi <ugilio@gmail.com>
Signed-off-by: James Bottomley <JBottomley@Odin.com>
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In drivers/scsi/scsi_devinfo.c, the scsi_dev_info_list_del_keyed() and
scsi_get_device_flags_keyed() routines contain a large amount of
duplicate code for finding vendor/product matches in a
scsi_dev_info_list. This patch factors out the duplicate code and
puts it in a separate function, scsi_dev_info_list_find().
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Suggested-by: Giulio Bernardi <ugilio@gmail.com>
Signed-off-by: James Bottomley <JBottomley@Odin.com>
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the kernel prints some warnings when compiled with CONFIG_DMA_API_DEBUG.
This is because the fnic driver doesn't check the return value of
pci_map_single().
[ 11.942770] scsi host12: fnic
[ 11.950811] ------------[ cut here ]------------
[ 11.950818] WARNING: at lib/dma-debug.c:937 check_unmap+0x47b/0x920()
[ 11.950821] fnic 0000:0c:00.0: DMA-API: device driver failed to check map error[device address=0x0000002020a30040] [size=44 bytes] [mapped as single]
Signed-off-by: Maurizio Lombardi <mlombard@redhat.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed By: Tomas Henzl <thenzl@redhat.com>
Signed-off-by: James Bottomley <JBottomley@Odin.com>
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We would like to get the following updates in:
Revert ownership to "Emulex" from "Avago Technologies"
Signed-off-by: Ketan Mukadam <ketan.mukadam@avagotech.com>
Reviewed-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <JBottomley@Odin.com>
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Signed-off-by: Ketan Mukadam <ketan.mukadam@avagotech.com>
Reviewed-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <JBottomley@Odin.com>
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Do not log error for netevents that need no action such as
NETDEV_REGISTER 0x0005, NETDEV_CHANGEADDR, and NETDEV_CHANGENAME.
It results in logging error messages such as these
[ 35.315872] bnx2fc: Unknown netevent 5
[ 35.315935] bnx2fc: Unknown netevent 8
[ 35.353866] bnx2fc: Unknown netevent 10
and generating bug reports.
Remove logging this message as an ERROR instead of turning them into
either DEBUG or INFO level messages.
Signed-off-by: Shirish Pargaonkar <spargaonkar@suse.com>
Acked-by: Eddie Wai <eddie.wai@broadcom.com>
Acked-by: Chad Dupuis <chad.dupuis@qlogic.com>
Signed-off-by: James Bottomley <JBottomley@Odin.com>
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Signed-off-by: Dick Kennedy <dick.kennedy@avagotech.com>
Signed-off-by: James Smart <james.smart@avagotech.com>
Signed-off-by: James Bottomley <JBottomley@Odin.com>
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Initial link up defaults were not properly being tracked relative to
initial FLOGI or pt2pt PLOGI. Add code to initialize them.
Signed-off-by: Dick Kennedy <dick.kennedy@avagotech.com>
Signed-off-by: James Smart <james.smart@avagotech.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: James Bottomley <JBottomley@Odin.com>
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Forgot to clear FCF Discovery in-progress flag upon FLOGI failures.
Thus we didn't restart FLOGI.
Signed-off-by: Dick Kennedy <dick.kennedy@avagotech.com>
Signed-off-by: James Smart <james.smart@avagotech.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: James Bottomley <JBottomley@Odin.com>
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aborted
Fix for discovery failure in PT2PT when FLOGI's ELS ACC response gets aborted
Change login state machine to:
- Restart FLOGI if prior is ABTS'd
- Reject incoming FLOGIs if we have one pending
The above ensures that we always finish FLOGI processing, regardless
of who initated FLOGI, before processing PLOGI's.
Signed-off-by: Dick Kennedy <dick.kennedy@avagotech.com>
Signed-off-by: James Smart <james.smart@avagotech.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: James Bottomley <JBottomley@Odin.com>
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Signed-off-by: Dick Kennedy <dick.kennedy@avagotech.com>
Signed-off-by: James Smart <james.smart@avagotech.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: James Bottomley <JBottomley@Odin.com>
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lpfc_send_rscn_event() allocates data for sizeof(struct
lpfc_rscn_event_header) + payload_len, but claims that the data has size
of sizeof(struct lpfc_els_event_header) + payload_len. That leads to
buffer overruns.
Signed-off-by: Ales Novak <alnovak@suse.cz>
Signed-off-by: James Smart <james.smart@avagotech.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Sebastian Herbszt <herbszt@gmx.de>
Signed-off-by: James Bottomley <JBottomley@Odin.com>
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Remove set but not used variables.
Signed-off-by: Sebastian Herbszt <herbszt@gmx.de>
Signed-off-by: James Smart <james.smart@avagotech.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: James Bottomley <JBottomley@Odin.com>
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comply with function prototype
This makes the function lpfc_sli4_mbox_completion's definition
static now in order to comply with its prototype being also
declared as static too.
Signed-off-by: Nicholas Krause <xerofoify@gmail.com>
Signed-off-by: James Smart <james.smart@avagotech.com>
Reviewed-by: Sebastian Herbszt <herbszt@gmx.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: James Bottomley <JBottomley@Odin.com>
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This patch allows the LPFC to start up without a fatal kernel bug based
on an exceeded KMALLOC_MAX_SIZE and a too large NR_CPU-based maskbits
field. The bug was based on the number of CPU cores in a system.
Using the get_cpu_mask() function declared in kernel/cpu.c allows the
driver to load on the community kernel 4.2 RC1.
Below is the kernel bug reproduced:
8<--------------------------------------------------------------------
2199382.828437 ( 0.005216)| lpfc 0003:02:00.0: enabling device (0140 -> 0142)
2199382.999272 ( 0.170835)| ------------[ cut here ]------------
2199382.999337 ( 0.000065)| WARNING: CPU: 84 PID: 404 at mm/slab_common.c:653 kmalloc_slab+0x2f/0x89()
2199383.004534 ( 0.005197)| Modules linked in: lpfc(+) usbcore(+) mptctl scsi_transport_fc sg lpc_ich i2c_i801 usb_common tpm_tis mfd_core tpm acpi_cpufreq button scsi_dh_alua scsi_dh_rdacusbcore: registered new device driver usb
2199383.020568 ( 0.016034)|
2199383.020581 ( 0.000013)| scsi_dh_hp_sw scsi_dh_emc scsi_dh gru thermal sata_nv processor piix fan thermal_sysehci_hcd: USB 2.0 'Enhanced' Host Controller (EHCI) Driver
2199383.035288 ( 0.014707)|
2199383.035306 ( 0.000018)| hwmon ata_piix
2199383.035336 ( 0.000030)| CPU: 84 PID: 404 Comm: kworker/84:0 Not tainted 3.18.0-rc2-gat-00106-ga7ca10f-dirty #178
2199383.047077 ( 0.011741)| ehci-pci: EHCI PCI platform driver
2199383.047134 ( 0.000057)| Hardware name: SGI UV2000/ROMLEY, BIOS SGI UV 2000/3000 series BIOS 01/15/2013
2199383.056245 ( 0.009111)| Workqueue: events work_for_cpu_fn
2199383.066174 ( 0.009929)| 000000000000028d ffff88eef827bbe8 ffffffff815a542f 000000000000028d
2199383.069545 ( 0.003371)| ffffffff810ea142 ffff88eef827bc28 ffffffff8104365c ffff88eefe4006c8
2199383.076214 ( 0.006669)| 0000000000000000 00000000000080d0 0000000000000000 0000000000000004
2199383.079213 ( 0.002999)| Call Trace:
2199383.084084 ( 0.004871)| [<ffffffff815a542f>] dump_stack+0x49/0x62
2199383.087283 ( 0.003199)| [<ffffffff810ea142>] ? kmalloc_slab+0x2f/0x89
2199383.091415 ( 0.004132)| [<ffffffff8104365c>] warn_slowpath_common+0x77/0x92
2199383.095197 ( 0.003782)| [<ffffffff8104368c>] warn_slowpath_null+0x15/0x17
2199383.103336 ( 0.008139)| [<ffffffff810ea142>] kmalloc_slab+0x2f/0x89
2199383.107082 ( 0.003746)| [<ffffffff8110fd9e>] __kmalloc+0x13/0x16a
2199383.112531 ( 0.005449)| [<ffffffffa01a8ed9>] lpfc_pci_probe_one_s4+0x105b/0x1644 [lpfc]
2199383.115316 ( 0.002785)| [<ffffffff81302b92>] ? pci_bus_read_config_dword+0x75/0x87
2199383.123431 ( 0.008115)| [<ffffffffa01a951f>] lpfc_pci_probe_one+0x5d/0xcb5 [lpfc]
2199383.127364 ( 0.003933)| [<ffffffff81497119>] ? dbs_check_cpu+0x168/0x177
2199383.136438 ( 0.009074)| [<ffffffff81496fa5>] ? gov_queue_work+0xb4/0xc0
2199383.140407 ( 0.003969)| [<ffffffff8130b2a1>] local_pci_probe+0x1e/0x52
2199383.143105 ( 0.002698)| [<ffffffff81052c47>] work_for_cpu_fn+0x13/0x1b
2199383.147315 ( 0.004210)| [<ffffffff81054965>] process_one_work+0x222/0x35e
2199383.151379 ( 0.004064)| [<ffffffff81054e76>] worker_thread+0x3d5/0x46e
2199383.159402 ( 0.008023)| [<ffffffff81054aa1>] ? process_one_work+0x35e/0x35e
2199383.163097 ( 0.003695)| [<ffffffff810599c6>] kthread+0xc8/0xd2
2199383.167476 ( 0.004379)| [<ffffffff810598fe>] ? kthread_freezable_should_stop+0x5b/0x5b
2199383.176434 ( 0.008958)| [<ffffffff815a8cac>] ret_from_fork+0x7c/0xb0
2199383.180086 ( 0.003652)| [<ffffffff810598fe>] ? kthread_freezable_should_stop+0x5b/0x5b
2199383.192333 ( 0.012247)| ehci-pci 0000:00:1a.0: EHCI Host Controller
-------------------------------------------------------------------->8
The proposed solution was approved by James Smart at Emulex and tested
on a UV2 machine with 6144 cores. With the fix, the LPFC module loads
with no unwanted effects on the system.
Signed-off-by: Ian Mitchell <imitchell@sgi.com>
Signed-off-by: Alex Thorlton <athorlton@sgi.com>
Suggested-by: Robert Elliot <elliott@hp.com>
[james.smart: resolve unused variable warning]
Signed-off-by: James Smart <james.smart@avagotech.com>
Signed-off-by: James Bottomley <JBottomley@Odin.com>
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Destroy lpfc_hba_index IDR on module exit, reclaiming the allocated memory.
This was detected by the following semantic patch (written by Luis Rodriguez
<mcgrof@suse.com>)
<SmPL>
@ defines_module_init @
declarer name module_init, module_exit;
declarer name DEFINE_IDR;
identifier init;
@@
module_init(init);
@ defines_module_exit @
identifier exit;
@@
module_exit(exit);
@ declares_idr depends on defines_module_init && defines_module_exit @
identifier idr;
@@
DEFINE_IDR(idr);
@ on_exit_calls_destroy depends on declares_idr && defines_module_exit @
identifier declares_idr.idr, defines_module_exit.exit;
@@
exit(void)
{
...
idr_destroy(&idr);
...
}
@ missing_module_idr_destroy depends on declares_idr && defines_module_exit && !on_exit_calls_destroy @
identifier declares_idr.idr, defines_module_exit.exit;
@@
exit(void)
{
...
+idr_destroy(&idr);
}
</SmPL>
Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: James Smart <james.smart@avagotech.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: James Bottomley <JBottomley@Odin.com>
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Currently the module parameter lpfc_sg_seg_count does not have effect
for sli3 devices.
In lpfc_sli_driver_resource_setup(), which is used for sli3, the code
writes the configured sg_seg_cnt into lpfc_template.sg_tablesize.
But lpfc_template is the template used for sli4 only. Thus the value should
correctly be written to lpfc_template_s3->sg_tablesize.
This patch is for kernel 4.1-rc5, but is tested with lpfc 10.2.405.26 only.
Signed-off-by: Bodo Stroesser <bstroesser@ts.fujitsu.com>
Signed-off-by: James Smart <james.smart@avagotech.com>
Reviewed-by: Sebastian Herbszt <herbszt@gmx.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: James Bottomley <JBottomley@Odin.com>
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kzalloc() returns a void pointer - no need to cast it in
drivers/scsi/lpfc/lpfc_init.c::lpfc_sli_driver_resource_setup()
Signed-off-by: Firo Yang <firogm@gmail.com>
Signed-off-by: James Smart <james.smart@avagotech.com>
Signed-off-by: James Bottomley <JBottomley@Odin.com>
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Remove trailing space from model description.
Signed-off-by: Sebastian Herbszt <herbszt@gmx.de>
Signed-off-by: James Smart <james.smart@avagotech.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: James Bottomley <JBottomley@Odin.com>
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3w controller don't dma map small single SGL entry commands but instead
bounce buffer them. Add a helper to identify these commands and don't
call scsi_dma_unmap for them.
Based on an earlier patch from James Bottomley.
Fixes: 118c85 ("3w-9xxx: fix command completion race")
Reported-by: Tóth Attila <atoth@atoth.sote.hu>
Tested-by: Tóth Attila <atoth@atoth.sote.hu>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Adam Radford <aradford@gmail.com>
Signed-off-by: James Bottomley <JBottomley@Odin.com>
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This fixes a bug in recent kernels which results in failure to boot
on systems that have multipath SCSI disks. I observed this failure
on a POWER8 server where all the disks are multipath SCSI disks.
The symptoms are several messages like this on the console:
[ 3.018700] device-mapper: table: 253:0: multipath: error attaching hardware handler
[ 3.018828] device-mapper: ioctl: error adding target to table
and the system does not find its disks, and therefore fails to boot.
Bisection revealed that the bug was introduced in commit 566079c849cf,
"dm-mpath, scsi_dh: request scsi_dh modules in scsi_dh, not dm-mpath".
The specific reason for the failure is that where we previously loaded
the "scsi_dh_alua" module, we are now trying to load the "alua" module,
which doesn't exist.
To fix this, we change the request_module call in scsi_dh_lookup()
to prepend "scsi_dh_" to the name, just like the old code in
drivers/md/dm-mpath.c:parse_hw_handler() used to do.
[jejb: also fixes issue spotted by Sasha Levin that formatting
characters could be passed in via sysfs and cause issues with
request_module()]
Fixes: 566079c849cf
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Cc: Sasha Levin <sasha.levin@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: James Bottomley <JBottomley@Odin.com>
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Connection last_ping is not being updated when iscsi_send_nopout fails.
Not updating the last_ping will cause firing a timer to a past time
(last_ping + ping_tmo < current_time) which triggers an infinite loop of
iscsi_check_transport_timeouts() and hogs the cpu.
Fix this issue by checking the return value of iscsi_send_nopout.
If it fails set the next_timeout to one second later.
Signed-off-by: Ariel Nahum <arieln@mellanox.com>
Signed-off-by: Sagi Grimberg <sagig@mellanox.com>
Reviewed-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <JBottomley@Odin.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/jesper/cris
Pull CRIS updates from Jesper Nilsson:
"Mostly removal of old cruft of which we can use a generic version, or
fixes for code not commonly run in the cris port, but also additions
to enable some good debug"
* tag 'cris-for-4.3' of git://git.kernel.org/pub/scm/linux/kernel/git/jesper/cris: (25 commits)
CRISv10: delete unused lib/dmacopy.c
CRISv10: delete unused lib/old_checksum.c
CRIS: fix switch_mm() lockdep splat
CRISv32: enable LOCKDEP_SUPPORT
CRIS: add STACKTRACE_SUPPORT
CRISv32: annotate irq enable in idle loop
CRISv32: add support for irqflags tracing
CRIS: UAPI: use generic types.h
CRIS: UAPI: use generic shmbuf.h
CRIS: UAPI: use generic msgbuf.h
CRIS: UAPI: use generic socket.h
CRIS: UAPI: use generic sembuf.h
CRIS: UAPI: use generic sockios.h
CRIS: UAPI: use generic auxvec.h
CRIS: UAPI: use generic headers via Kbuild
CRIS: UAPI: fix elf.h export
CRIS: don't make asm/elf.h depend on asm/user.h
CRIS: UAPI: fix ptrace.h
CRISv32: Squash compile warnings for axisflashmap
CRISv32: Add GPIO driver to the default configs
...
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rq_data_dir() returns either READ or WRITE (0 == READ, 1 == WRITE), not
a boolean value.
Now, admittedly the "!= 0" doesn't really change the value (0 stays as
zero, 1 stays as one), but it's not only redundant, it confuses gcc, and
causes gcc to warn about the construct
switch (rq_data_dir(req)) {
case READ:
...
case WRITE:
...
that we have in a few drivers.
Now, the gcc warning is silly and stupid (it seems to warn not about the
switch value having a different type from the case statements, but about
_any_ boolean switch value), but in this case the code itself is silly
and stupid too, so let's just change it, and get rid of warnings like
this:
drivers/block/hd.c: In function ‘hd_request’:
drivers/block/hd.c:630:11: warning: switch condition has boolean value [-Wswitch-bool]
switch (rq_data_dir(req)) {
The odd '!= 0' came in when "cmd_flags" got turned into a "u64" in
commit 5953316dbf90 ("block: make rq->cmd_flags be 64-bit") and is
presumably because the old code (that just did a logical 'and' with 1)
would then end up making the type of rq_data_dir() be u64 too.
But if we want to retain the old regular integer type, let's just cast
the result to 'int' rather than use that rather odd '!= 0'.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Fix up the writeback plugging introduced in commit d353d7587d02
("writeback: plug writeback at a high level") that then caused problems
due to the unplug happening with a spinlock held.
* writeback-plugging:
writeback: plug writeback in wb_writeback() and writeback_inodes_wb()
Revert "writeback: plug writeback at a high level"
|
|
We had to revert the pluggin in writeback_sb_inodes() because the
wb->list_lock is held, but we could easily plug at a higher level before
taking that lock, and unplug after releasing it. This does that.
Chris will run performance numbers, just to verify that this approach is
comparable to the alternative (we could just drop and re-take the lock
around the blk_finish_plug() rather than these two commits.
I'd have preferred waiting for actual performance numbers before picking
one approach over the other, but I don't want to release rc1 with the
known "sleeping function called from invalid context" issue, so I'll
pick this cleanup version for now. But if the numbers show that we
really want to plug just at the writeback_sb_inodes() level, and we
should just play ugly games with the spinlock, we'll switch to that.
Cc: Chris Mason <clm@fb.com>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Neil Brown <neilb@suse.de>
Cc: Jan Kara <jack@suse.cz>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
I didn't notice this when merging the thermal code from Zhang, but his
merge (commit 5a924a07f882: "Merge branches 'thermal-core' and
'thermal-intel' of .git into next") of the thermal-core and
thermal-intel branches was wrong.
In thermal-core, commit 17e8351a7739 ("thermal: consistently use int for
temperatures") converted the thermal layer to use "int" for
temperatures.
But in parallel, in the thermal-intel branch commit d0a12625d2ff
("thermal: Add Intel PCH thermal driver") added support for the intel
PCH thermal sensor using the old interfaces that used "unsigned long"
pointers.
This resulted in warnings like this:
drivers/thermal/intel_pch_thermal.c:184:14: warning: initialization from incompatible pointer type [-Wincompatible-pointer-types]
.get_temp = pch_thermal_get_temp,
^
drivers/thermal/intel_pch_thermal.c:184:14: note: (near initialization for ‘tzd_ops.get_temp’)
drivers/thermal/intel_pch_thermal.c:186:19: warning: initialization from incompatible pointer type [-Wincompatible-pointer-types]
.get_trip_temp = pch_get_trip_temp,
^
drivers/thermal/intel_pch_thermal.c:186:19: note: (near initialization for ‘tzd_ops.get_trip_temp’)
This fixes it.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Merge fourth patch-bomb from Andrew Morton:
- sys_membarier syscall
- seq_file interface changes
- a few misc fixups
* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
revert "ocfs2/dlm: use list_for_each_entry instead of list_for_each"
mm/early_ioremap: add explicit #include of asm/early_ioremap.h
fs/seq_file: convert int seq_vprint/seq_printf/etc... returns to void
selftests: enhance membarrier syscall test
selftests: add membarrier syscall test
sys_membarrier(): system-wide memory barrier (generic, x86)
MODSIGN: fix a compilation warning in extract-cert
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|
Newer bitfiles needs the reduced clk even for SMP builds
Cc: <stable@vger.kernel.org> #4.2
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Pull NTB fixes from Jon Mason:
"NTB bug and documentation fixes, new device IDs, performance
improvements, and adding a mailing list to MAINTAINERS for NTB"
* tag 'ntb-4.3' of git://github.com/jonmason/ntb:
NTB: Fix range check on memory window index
NTB: Improve index handling in B2B MW workaround
NTB: Fix documentation for ntb_peer_db_clear.
NTB: Fix documentation for ntb_link_is_up
NTB: Use unique DMA channels for TX and RX
NTB: Remove dma_sync_wait from ntb_async_rx
NTB: Clean up QP stats info
NTB: Make the transport list in order of discovery
NTB: Add PCI Device IDs for Broadwell Xeon
NTB: Add flow control to the ntb_netdev
NTB: Add list to MAINTAINERS
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|
git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input
Pull more input updates from Dmitry Torokhov:
"Second round of updates for the input subsystem.
This introduces two brand new touchscreen drivers (Colibri and
imx6ul_tsc), some small driver fixes, and we are no longer report
errors from evdev_flush() as users do not really have a way of
handling errors, error codes that we were returning were not on the
list of errors supposed to be returned by close(), and errors were
causing issues with one of older versions of systemd"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input:
Input: imx_keypad - remove obsolete comment
Input: touchscreen - add imx6ul_tsc driver support
Input: Add touchscreen support for Colibri VF50
Input: i8042 - lower log level for "no controller" message
Input: evdev - do not report errors form flush()
Input: elants_i2c - extend the calibration timeout to 12 seconds
Input: sparcspkr - fix module autoload for OF platform drivers
Input: regulator-haptic - fix module autoload for OF platform driver
Input: pwm-beeper - fix module autoload for OF platform driver
Input: ab8500-ponkey - Fix module autoload for OF platform driver
Input: cyttsp - remove unnecessary MODULE_ALIAS()
Input: elan_i2c - add ACPI ID "ELAN1000"
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|
git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull more power management and ACPI updates from Rafael Wysocki:
"These are mostly fixes and cleanups on top of the previous PM+ACPI
pull request (cpufreq core and drivers, cpuidle, generic power domains
framework). Some of them didn't make to that pull request and some
fix issues introduced by it.
The only really new thing is the support for suspend frequency in the
cpufreq-dt driver, but it is needed to fix an issue with Exynos
platforms.
Specifics:
- build fix for the new Mediatek MT8173 cpufreq driver (Guenter
Roeck).
- generic power domains framework fixes (power on error code path,
subdomain removal) and cleanup of a deprecated API user (Geert
Uytterhoeven, Jon Hunter, Ulf Hansson).
- cpufreq-dt driver fixes including two fixes for bugs related to the
new Operating Performance Points Device Tree bindings introduced
recently (Viresh Kumar).
- suspend frequency support for the cpufreq-dt driver (Bartlomiej
Zolnierkiewicz, Viresh Kumar).
- cpufreq core cleanups (Viresh Kumar).
- intel_pstate driver fixes (Chen Yu, Kristen Carlson Accardi).
- additional sanity check in the cpuidle core (Xunlei Pang).
- fix for a comment related to CPU power management (Lina Iyer)"
* tag 'pm+acpi-4.3-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
intel_pstate: fix PCT_TO_HWP macro
intel_pstate: Fix user input of min/max to legal policy region
PM / OPP: Return suspend_opp only if it is enabled
cpufreq-dt: add suspend frequency support
cpufreq: allow cpufreq_generic_suspend() to work without suspend frequency
PM / OPP: add dev_pm_opp_get_suspend_opp() helper
staging: board: Migrate away from __pm_genpd_name_add_device()
cpufreq: Use __func__ to print function's name
cpufreq: staticize cpufreq_cpu_get_raw()
PM / Domains: Ensure subdomain is not in use before removing
cpufreq: Add ARM_MT8173_CPUFREQ dependency on THERMAL
cpuidle/coupled: Add sanity check for safe_state_index
PM / Domains: Try power off masters in error path of __pm_genpd_poweron()
cpufreq: dt: Tolerance applies on both sides of target voltage
cpufreq: dt: Print error on failing to mark OPPs as shared
cpufreq: dt: Check OPP count before marking them shared
kernel/cpu_pm: fix cpu_cluster_pm_exit comment
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git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending
Pull SCSI target updates from Nicholas Bellinger:
"Here are the outstanding target-pending updates for v4.3-rc1.
Mostly bug-fixes and minor changes this round. The fallout from the
big v4.2-rc1 RCU conversion have (thus far) been minimal.
The highlights this round include:
- Move sense handling routines into scsi_common code (Sagi)
- Return ABORTED_COMMAND sense key for PI errors (Sagi)
- Add tpg_enabled_sendtargets attribute for disabled iscsi-target
discovery (David)
- Shrink target struct se_cmd by rearranging fields (Roland)
- Drop iSCSI use of mutex around max_cmd_sn increment (Roland)
- Replace iSCSI __kernel_sockaddr_storage with sockaddr_storage (Andy +
Chris)
- Honor fabric max_data_sg_nents I/O transfer limit (Arun + Himanshu +
nab)
- Fix EXTENDED_COPY >= v4.1 regression OOPsen (Alex + nab)"
* 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending: (37 commits)
target: use stringify.h instead of own definition
target/user: Fix UFLAG_UNKNOWN_OP handling
target: Remove no-op conditional
target/user: Remove unused variable
target: Fix max_cmd_sn increment w/o cmdsn mutex regressions
target: Attach EXTENDED_COPY local I/O descriptors to xcopy_pt_sess
target/qla2xxx: Honor max_data_sg_nents I/O transfer limit
target/iscsi: Replace __kernel_sockaddr_storage with sockaddr_storage
target/iscsi: Replace conn->login_ip with login_sockaddr
target/iscsi: Keep local_ip as the actual sockaddr
target/iscsi: Fix np_ip bracket issue by removing np_ip
target: Drop iSCSI use of mutex around max_cmd_sn increment
qla2xxx: Update tcm_qla2xxx module description to 24xx+
iscsi-target: Add tpg_enabled_sendtargets for disabled discovery
drivers: target: Drop unlikely before IS_ERR(_OR_NULL)
target: check DPO/FUA usage for COMPARE AND WRITE
target: Shrink struct se_cmd by rearranging fields
target: Remove cmd->se_ordered_id (unused except debug log lines)
target: add support for START_STOP_UNIT SCSI opcode
target: improve unsupported opcode message
...
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Pull second round of SCSI updates from James Bottomley:
"There's one late arriving patch here (added today), fixing a build
issue which the scsi_dh patch set in here uncovered. Other than that,
everything has been incubated in -next and the checkers for a week.
The major pieces of this patch are a set patches facilitating better
integration between scsi and scsi_dh (the device handling layer used
by multi-path; all the dm parts are acked by Mike Snitzer).
This also includes driver updates for mp3sas, scsi_debug and an
assortment of bug fixes"
* tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi: (50 commits)
scsi_dh: fix randconfig build error
scsi: fix scsi_error_handler vs. scsi_host_dev_release race
fcoe: Convert use of __constant_htons to htons
mpt2sas: setpci reset kernel oops fix
pm80xx: Don't override ts->stat on IO_OPEN_CNX_ERROR_HW_RESOURCE_BUSY
lpfc: Fix possible use-after-free and double free in lpfc_mbx_cmpl_rdp_page_a2()
bfa: Fix incorrect de-reference of pointer
bfa: Fix indentation
scsi_transport_sas: Remove check for SAS expander when querying bay/enclosure IDs.
scsi_debug: resp_request: remove unused variable
scsi_debug: fix REPORT LUNS Well Known LU
scsi_debug: schedule_resp fix input variable check
scsi_debug: make dump_sector static
scsi_debug: vfree is null safe so drop the check
scsi_debug: use SCSI_W_LUN_REPORT_LUNS instead of SAM2_WLUN_REPORT_LUNS;
scsi_debug: define pr_fmt() for consistent logging
mpt2sas: Refcount fw_events and fix unsafe list usage
mpt2sas: Refcount sas_device objects and fix unsafe list usage
scsi_dh: return SCSI_DH_NOTCONN in scsi_dh_activate()
scsi_dh: don't allow to detach device handlers at runtime
...
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git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media
Pull media updates from Mauro Carvalho Chehab:
"A series of patches that move part of the code used to allocate memory
from the media subsystem to the mm subsystem"
[ The mm parts have been acked by VM people, and the series was
apparently in -mm for a while - Linus ]
* tag 'media/v4.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media:
[media] drm/exynos: Convert g2d_userptr_get_dma_addr() to use get_vaddr_frames()
[media] media: vb2: Remove unused functions
[media] media: vb2: Convert vb2_dc_get_userptr() to use frame vector
[media] media: vb2: Convert vb2_vmalloc_get_userptr() to use frame vector
[media] media: vb2: Convert vb2_dma_sg_get_userptr() to use frame vector
[media] vb2: Provide helpers for mapping virtual addresses
[media] media: omap_vout: Convert omap_vout_uservirt_to_phys() to use get_vaddr_pfns()
[media] mm: Provide new get_vaddr_frames() helper
[media] vb2: Push mmap_sem down to memops
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git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-edac
Pull edac updates from Mauro Carvalho Chehab:
"Two EDAC fixes for Intel systems (Haswell and Ivy Bridge)"
* tag 'edac/v4.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-edac:
sb_edac: correctly fetch DIMM width on Ivy Bridge and Haswell
sb_edac: look harder for DDRIO on Haswell systems
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git://git.kernel.org/pub/scm/linux/kernel/git/rzhang/linux
Pull thermal updates from Zhang Rui:
- use int instead of unsigned long to represent temperature to avoid
bogus overheat detection when negative temperature reported. From
Sascha Hauer.
- export available thermal governors information to user space via
sysfs. From Wei Ni.
- introduce new thermal driver for Wildcat Point platform controller
hub, which uses PCH thermal sensor and associated critical and hot
trip points. From Tushar Dave.
- add suuport for Intel Skylake and Denlow platforms in powerclamp
driver.
- some small cleanups in thermal core.
* 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/rzhang/linux:
thermal: Add Intel PCH thermal driver
thermal: Add comment explaining test for critical temperature
thermal: Use IS_ENABLED instead of #ifdef
thermal: remove unnecessary call to thermal_zone_device_set_polling
thermal: trivial: fix typo in comment
thermal: consistently use int for temperatures
thermal: add available policies sysfs attribute
thermal/powerclamp: add cpu id for denlow platform
thermal/powerclamp: add cpu id for Skylake u/y
thermal/powerclamp: add cpu id for skylake h/s
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Revert commit f83c7b5e9fd6 ("ocfs2/dlm: use list_for_each_entry instead
of list_for_each").
list_for_each_entry() will dereference its `pos' argument, which can be
NULL in dlm_process_recovery_data().
Reported-by: Julia Lawall <julia.lawall@lip6.fr>
Reported-by: Fengguang Wu <fengguang.wu@gmail.com>
Cc: Joseph Qi <joseph.qi@huawei.com>
Cc: Mark Fasheh <mfasheh@suse.de>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Commit 6b0f68e32ea8 ("mm: add utility for early copy from unmapped ram")
introduces a function copy_from_early_mem() into mm/early_ioremap.c
which itself calls early_memremap()/early_memunmap(). However, since
early_memunmap() has not been declared yet at this point in the .c file,
nor by any explicitly included header files, we are depending on a
transitive include of asm/early_ioremap.h to declare it, which is
fragile.
So instead, include this header explicitly.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Mark Salter <msalter@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The seq_<foo> function return values were frequently misused.
See: commit 1f33c41c03da ("seq_file: Rename seq_overflow() to
seq_has_overflowed() and make public")
All uses of these return values have been removed, so convert the
return types to void.
Miscellanea:
o Move seq_put_decimal_<type> and seq_escape prototypes closer the
other seq_vprintf prototypes
o Reorder seq_putc and seq_puts to return early on overflow
o Add argument names to seq_vprintf and seq_printf
o Update the seq_escape kernel-doc
o Convert a couple of leading spaces to tabs in seq_escape
Signed-off-by: Joe Perches <joe@perches.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mark Brown <broonie@kernel.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Update the membarrier syscall self-test to match the membarrier
interface. Extend coverage of the interface. Consider ENOSYS as a
"SKIP" test, since it is a valid configuration, but does not allow
testing the system call.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Pranith Kumar <bobby.prani@gmail.com>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Add a self test for the membarrier system call.
Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Here is an implementation of a new system call, sys_membarrier(), which
executes a memory barrier on all threads running on the system. It is
implemented by calling synchronize_sched(). It can be used to
distribute the cost of user-space memory barriers asymmetrically by
transforming pairs of memory barriers into pairs consisting of
sys_membarrier() and a compiler barrier. For synchronization primitives
that distinguish between read-side and write-side (e.g. userspace RCU
[1], rwlocks), the read-side can be accelerated significantly by moving
the bulk of the memory barrier overhead to the write-side.
The existing applications of which I am aware that would be improved by
this system call are as follows:
* Through Userspace RCU library (http://urcu.so)
- DNS server (Knot DNS) https://www.knot-dns.cz/
- Network sniffer (http://netsniff-ng.org/)
- Distributed object storage (https://sheepdog.github.io/sheepdog/)
- User-space tracing (http://lttng.org)
- Network storage system (https://www.gluster.org/)
- Virtual routers (https://events.linuxfoundation.org/sites/events/files/slides/DPDK_RCU_0MQ.pdf)
- Financial software (https://lkml.org/lkml/2015/3/23/189)
Those projects use RCU in userspace to increase read-side speed and
scalability compared to locking. Especially in the case of RCU used by
libraries, sys_membarrier can speed up the read-side by moving the bulk of
the memory barrier cost to synchronize_rcu().
* Direct users of sys_membarrier
- core dotnet garbage collector (https://github.com/dotnet/coreclr/issues/198)
Microsoft core dotnet GC developers are planning to use the mprotect()
side-effect of issuing memory barriers through IPIs as a way to implement
Windows FlushProcessWriteBuffers() on Linux. They are referring to
sys_membarrier in their github thread, specifically stating that
sys_membarrier() is what they are looking for.
To explain the benefit of this scheme, let's introduce two example threads:
Thread A (non-frequent, e.g. executing liburcu synchronize_rcu())
Thread B (frequent, e.g. executing liburcu
rcu_read_lock()/rcu_read_unlock())
In a scheme where all smp_mb() in thread A are ordering memory accesses
with respect to smp_mb() present in Thread B, we can change each
smp_mb() within Thread A into calls to sys_membarrier() and each
smp_mb() within Thread B into compiler barriers "barrier()".
Before the change, we had, for each smp_mb() pairs:
Thread A Thread B
previous mem accesses previous mem accesses
smp_mb() smp_mb()
following mem accesses following mem accesses
After the change, these pairs become:
Thread A Thread B
prev mem accesses prev mem accesses
sys_membarrier() barrier()
follow mem accesses follow mem accesses
As we can see, there are two possible scenarios: either Thread B memory
accesses do not happen concurrently with Thread A accesses (1), or they
do (2).
1) Non-concurrent Thread A vs Thread B accesses:
Thread A Thread B
prev mem accesses
sys_membarrier()
follow mem accesses
prev mem accesses
barrier()
follow mem accesses
In this case, thread B accesses will be weakly ordered. This is OK,
because at that point, thread A is not particularly interested in
ordering them with respect to its own accesses.
2) Concurrent Thread A vs Thread B accesses
Thread A Thread B
prev mem accesses prev mem accesses
sys_membarrier() barrier()
follow mem accesses follow mem accesses
In this case, thread B accesses, which are ensured to be in program
order thanks to the compiler barrier, will be "upgraded" to full
smp_mb() by synchronize_sched().
* Benchmarks
On Intel Xeon E5405 (8 cores)
(one thread is calling sys_membarrier, the other 7 threads are busy
looping)
1000 non-expedited sys_membarrier calls in 33s =3D 33 milliseconds/call.
* User-space user of this system call: Userspace RCU library
Both the signal-based and the sys_membarrier userspace RCU schemes
permit us to remove the memory barrier from the userspace RCU
rcu_read_lock() and rcu_read_unlock() primitives, thus significantly
accelerating them. These memory barriers are replaced by compiler
barriers on the read-side, and all matching memory barriers on the
write-side are turned into an invocation of a memory barrier on all
active threads in the process. By letting the kernel perform this
synchronization rather than dumbly sending a signal to every process
threads (as we currently do), we diminish the number of unnecessary wake
ups and only issue the memory barriers on active threads. Non-running
threads do not need to execute such barrier anyway, because these are
implied by the scheduler context switches.
Results in liburcu:
Operations in 10s, 6 readers, 2 writers:
memory barriers in reader: 1701557485 reads, 2202847 writes
signal-based scheme: 9830061167 reads, 6700 writes
sys_membarrier: 9952759104 reads, 425 writes
sys_membarrier (dyn. check): 7970328887 reads, 425 writes
The dynamic sys_membarrier availability check adds some overhead to
the read-side compared to the signal-based scheme, but besides that,
sys_membarrier slightly outperforms the signal-based scheme. However,
this non-expedited sys_membarrier implementation has a much slower grace
period than signal and memory barrier schemes.
Besides diminishing the number of wake-ups, one major advantage of the
membarrier system call over the signal-based scheme is that it does not
need to reserve a signal. This plays much more nicely with libraries,
and with processes injected into for tracing purposes, for which we
cannot expect that signals will be unused by the application.
An expedited version of this system call can be added later on to speed
up the grace period. Its implementation will likely depend on reading
the cpu_curr()->mm without holding each CPU's rq lock.
This patch adds the system call to x86 and to asm-generic.
[1] http://urcu.so
membarrier(2) man page:
MEMBARRIER(2) Linux Programmer's Manual MEMBARRIER(2)
NAME
membarrier - issue memory barriers on a set of threads
SYNOPSIS
#include <linux/membarrier.h>
int membarrier(int cmd, int flags);
DESCRIPTION
The cmd argument is one of the following:
MEMBARRIER_CMD_QUERY
Query the set of supported commands. It returns a bitmask of
supported commands.
MEMBARRIER_CMD_SHARED
Execute a memory barrier on all threads running on the system.
Upon return from system call, the caller thread is ensured that
all running threads have passed through a state where all memory
accesses to user-space addresses match program order between
entry to and return from the system call (non-running threads
are de facto in such a state). This covers threads from all pro=E2=80=90
cesses running on the system. This command returns 0.
The flags argument needs to be 0. For future extensions.
All memory accesses performed in program order from each targeted
thread is guaranteed to be ordered with respect to sys_membarrier(). If
we use the semantic "barrier()" to represent a compiler barrier forcing
memory accesses to be performed in program order across the barrier,
and smp_mb() to represent explicit memory barriers forcing full memory
ordering across the barrier, we have the following ordering table for
each pair of barrier(), sys_membarrier() and smp_mb():
The pair ordering is detailed as (O: ordered, X: not ordered):
barrier() smp_mb() sys_membarrier()
barrier() X X O
smp_mb() X O O
sys_membarrier() O O O
RETURN VALUE
On success, these system calls return zero. On error, -1 is returned,
and errno is set appropriately. For a given command, with flags
argument set to 0, this system call is guaranteed to always return the
same value until reboot.
ERRORS
ENOSYS System call is not implemented.
EINVAL Invalid arguments.
Linux 2015-04-15 MEMBARRIER(2)
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nicholas Miell <nmiell@comcast.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Stephen Hemminger <stephen@networkplumber.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Pranith Kumar <bobby.prani@gmail.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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