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author | Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | 2010-04-17 12:48:42 (GMT) |
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committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2010-06-14 23:37:26 (GMT) |
commit | 551d55a944b143ef26fbd482d1c463199d6f65cf (patch) | |
tree | 6911d3f8e8719ba5ca43c83acdf87cbc8276d7d1 /lib/Kconfig.debug | |
parent | 875352c94224c88f5aa28cb77206f993bd31b7a2 (diff) | |
download | linux-fsl-qoriq-551d55a944b143ef26fbd482d1c463199d6f65cf.tar.xz |
tree/tiny rcu: Add debug RCU head objects
Helps finding racy users of call_rcu(), which results in hangs because list
entries are overwritten and/or skipped.
Changelog since v4:
- Bissectability is now OK
- Now generate a WARN_ON_ONCE() for non-initialized rcu_head passed to
call_rcu(). Statically initialized objects are detected with
object_is_static().
- Rename rcu_head_init_on_stack to init_rcu_head_on_stack.
- Remove init_rcu_head() completely.
Changelog since v3:
- Include comments from Lai Jiangshan
This new patch version is based on the debugobjects with the newly introduced
"active state" tracker.
Non-initialized entries are all considered as "statically initialized". An
activation fixup (triggered by call_rcu()) takes care of performing the debug
object initialization without issuing any warning. Since we cannot increase the
size of struct rcu_head, I don't see much room to put an identifier for
statically initialized rcu_head structures. So for now, we have to live without
"activation without explicit init" detection. But the main purpose of this debug
option is to detect double-activations (double call_rcu() use of a rcu_head
before the callback is executed), which is correctly addressed here.
This also detects potential internal RCU callback corruption, which would cause
the callbacks to be executed twice.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
CC: David S. Miller <davem@davemloft.net>
CC: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
CC: akpm@linux-foundation.org
CC: mingo@elte.hu
CC: laijs@cn.fujitsu.com
CC: dipankar@in.ibm.com
CC: josh@joshtriplett.org
CC: dvhltc@us.ibm.com
CC: niv@us.ibm.com
CC: tglx@linutronix.de
CC: peterz@infradead.org
CC: rostedt@goodmis.org
CC: Valdis.Kletnieks@vt.edu
CC: dhowells@redhat.com
CC: eric.dumazet@gmail.com
CC: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Diffstat (limited to 'lib/Kconfig.debug')
-rw-r--r-- | lib/Kconfig.debug | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index e722e9d..142faa2 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -307,6 +307,12 @@ config DEBUG_OBJECTS_WORK work queue routines to track the life time of work objects and validate the work operations. +config DEBUG_OBJECTS_RCU_HEAD + bool "Debug RCU callbacks objects" + depends on DEBUG_OBJECTS && PREEMPT + help + Enable this to turn on debugging of RCU list heads (call_rcu() usage). + config DEBUG_OBJECTS_ENABLE_DEFAULT int "debug_objects bootup default value (0-1)" range 0 1 |