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author | Yong Zhang <yong.zhang0@gmail.com> | 2011-11-09 16:04:51 +0800 |
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committer | Greg Kroah-Hartman <gregkh@suse.de> | 2011-12-21 12:58:22 -0800 |
commit | f767f25ebc6a9233e50561657468f31bceb84a1e (patch) | |
tree | 707a1a8975b828244e73d1aa259a7135c4f2efb1 | |
parent | 7f37071e9df2344a7d7d066235ec72a0d1a4b013 (diff) | |
download | lwn-f767f25ebc6a9233e50561657468f31bceb84a1e.tar.gz lwn-f767f25ebc6a9233e50561657468f31bceb84a1e.zip |
lockdep, kmemcheck: Annotate ->lock in lockdep_init_map()
commit a33caeb118198286309859f014c0662f3ed54ed4 upstream.
Since commit f59de89 ("lockdep: Clear whole lockdep_map on initialization"),
lockdep_init_map() will clear all the struct. But it will break
lock_set_class()/lock_set_subclass(). A typical race condition
is like below:
CPU A CPU B
lock_set_subclass(lockA);
lock_set_class(lockA);
lockdep_init_map(lockA);
/* lockA->name is cleared */
memset(lockA);
__lock_acquire(lockA);
/* lockA->class_cache[] is cleared */
register_lock_class(lockA);
look_up_lock_class(lockA);
WARN_ON_ONCE(class->name !=
lock->name);
lock->name = name;
So restore to what we have done before commit f59de89 but annotate
->lock with kmemcheck_mark_initialized() to suppress the kmemcheck
warning reported in commit f59de89.
Reported-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Reported-by: Borislav Petkov <bp@alien8.de>
Suggested-by: Vegard Nossum <vegard.nossum@gmail.com>
Signed-off-by: Yong Zhang <yong.zhang0@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20111109080451.GB8124@zhy
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r-- | kernel/lockdep.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/kernel/lockdep.c b/kernel/lockdep.c index 91d67ce3a8d5..447960603fbd 100644 --- a/kernel/lockdep.c +++ b/kernel/lockdep.c @@ -44,6 +44,7 @@ #include <linux/stringify.h> #include <linux/bitops.h> #include <linux/gfp.h> +#include <linux/kmemcheck.h> #include <asm/sections.h> @@ -2874,7 +2875,12 @@ static int mark_lock(struct task_struct *curr, struct held_lock *this, void lockdep_init_map(struct lockdep_map *lock, const char *name, struct lock_class_key *key, int subclass) { - memset(lock, 0, sizeof(*lock)); + int i; + + kmemcheck_mark_initialized(lock, sizeof(*lock)); + + for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++) + lock->class_cache[i] = NULL; #ifdef CONFIG_LOCK_STAT lock->cpu = raw_smp_processor_id(); |