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| author | Jason Gunthorpe <jgunthorpe@obsidianresearch.com> | 2016-02-13 03:29:53 (GMT) |
|---|---|---|
| committer | Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> | 2016-06-25 14:26:35 (GMT) |
| commit | 4e26195f240d73150e8308ae42874702e3df8d2c (patch) | |
| tree | c0e8ff3604b09484393d10a927ed1e9a46a7ed0d /drivers/char/tpm/tpm-sysfs.c | |
| parent | 3635e2ec7cbb9aa054f8d4361dec27b0ca625905 (diff) | |
| download | linux-4e26195f240d73150e8308ae42874702e3df8d2c.tar.xz | |
tpm: Provide strong locking for device removal
Add a read/write semaphore around the ops function pointers so
ops can be set to null when the driver un-registers.
Previously the tpm core expected module locking to be enough to
ensure that tpm_unregister could not be called during certain times,
however that hasn't been sufficient for a long time.
Introduce a read/write semaphore around 'ops' so the core can set
it to null when unregistering. This provides a strong fence around
the driver callbacks, guaranteeing to the driver that no callbacks
are running or will run again.
For now the ops_lock is placed very high in the call stack, it could
be pushed down and made more granular in future if necessary.
Signed-off-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Reviewed-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Diffstat (limited to 'drivers/char/tpm/tpm-sysfs.c')
| -rw-r--r-- | drivers/char/tpm/tpm-sysfs.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/drivers/char/tpm/tpm-sysfs.c b/drivers/char/tpm/tpm-sysfs.c index d93736a..34e7fc7 100644 --- a/drivers/char/tpm/tpm-sysfs.c +++ b/drivers/char/tpm/tpm-sysfs.c @@ -295,5 +295,10 @@ int tpm_sysfs_add_device(struct tpm_chip *chip) void tpm_sysfs_del_device(struct tpm_chip *chip) { + /* The sysfs routines rely on an implicit tpm_try_get_ops, this + * function is called before ops is null'd and the sysfs core + * synchronizes this removal so that no callbacks are running or can + * run again + */ sysfs_remove_group(&chip->dev.parent->kobj, &tpm_dev_group); } |