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seqcount: Add lockdep functionality to seqcount/seqlock structures

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Currently seqlocks and seqcounts don't support lockdep.

After running across a seqcount related deadlock in the timekeeping
code, I used a less-refined and more focused variant of this patch
to narrow down the cause of the issue.

This is a first-pass attempt to properly enable lockdep functionality
on seqlocks and seqcounts.

Since seqcounts are used in the vdso gettimeofday code, I've provided
non-lockdep accessors for those needs.

I've also handled one case where there were nested seqlock writers
and there may be more edge cases.

Comments and feedback would be appreciated!

Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: netdev@vger.kernel.org
Link: http://lkml.kernel.org/r/1381186321-4906-3-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
John Stultz 2013-10-07 15:51:59 -07:00 • committed by Ingo Molnar
parent 827da44c61
commit 1ca7d67cf5
7 changed files with 90 additions and 21 deletions
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8
include/linux/init_task.h
View file

@ -32,10 +32,10 @@ extern struct fs_struct init_fs;
#endif
#ifdef CONFIG_CPUSETS
#define INIT_CPUSET_SEQ \
.mems_allowed_seq = SEQCNT_ZERO,
#define INIT_CPUSET_SEQ(tsk) \
.mems_allowed_seq = SEQCNT_ZERO(tsk.mems_allowed_seq),
#else
#define INIT_CPUSET_SEQ
#define INIT_CPUSET_SEQ(tsk)
#endif
#define INIT_SIGNALS(sig) { \
@ -220,7 +220,7 @@ extern struct task_group root_task_group;
INIT_FTRACE_GRAPH \
INIT_TRACE_RECURSION \
INIT_TASK_RCU_PREEMPT(tsk) \
INIT_CPUSET_SEQ \
INIT_CPUSET_SEQ(tsk) \
INIT_VTIME(tsk) \
}