Re: [tip:core/locking] lockdep, kmemcheck: Annotate ->lock inlockdep_init_map()

[David Rientjes]

On Tue, 6 Dec 2011, tip-bot for Yong Zhang wrote:

> Commit-ID:  d3d03d4fc5b1bec3a579112de170a9676e9d97cb
> Gitweb:     http://git.kernel.org/tip/d3d03d4fc5b1bec3a579112de170a9676e9d97cb
> Author:     Yong Zhang <yong.zhang0@xxxxxxxxx>
> AuthorDate: Wed, 9 Nov 2011 16:04:51 +0800
> Committer:  Ingo Molnar <mingo@xxxxxxx>
> CommitDate: Tue, 6 Dec 2011 08:16:51 +0100
> 
> lockdep, kmemcheck: Annotate ->lock in lockdep_init_map()
> 
> 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@xxxxxxxxx>
> Reported-by: Borislav Petkov <bp@xxxxxxxxx>
> Suggested-by: Vegard Nossum <vegard.nossum@xxxxxxxxx>
> Signed-off-by: Yong Zhang <yong.zhang0@xxxxxxxxx>
> Cc: Tejun Heo <tj@xxxxxxxxxx>
> Cc: David Rientjes <rientjes@xxxxxxxxxx>

Acked-by: David Rientjes <rientjes@xxxxxxxxxx>

> Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
> Link: http://lkml.kernel.org/r/20111109080451.GB8124@zhy
> Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
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