locking/lockdep: Detect and handle hist_lock ring buffer overwrite
authorByungchul Park <byungchul.park@lge.com>
Mon, 7 Aug 2017 07:12:53 +0000 (16:12 +0900)
committerIngo Molnar <mingo@kernel.org>
Thu, 10 Aug 2017 10:29:08 +0000 (12:29 +0200)
commit23f873d8f9526ed7e49a1a02a45f8afb9ae5fb84
treec926e87ad1197db61dca6677b5e7e7184271698a
parentb09be676e0ff25bd6d2e7637e26d349f9109ad75
locking/lockdep: Detect and handle hist_lock ring buffer overwrite

The ring buffer can be overwritten by hardirq/softirq/work contexts.
That cases must be considered on rollback or commit. For example,

          |<------ hist_lock ring buffer size ----->|
          ppppppppppppiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii
wrapped > iiiiiiiiiiiiiiiiiiiiiii....................

          where 'p' represents an acquisition in process context,
          'i' represents an acquisition in irq context.

On irq exit, crossrelease tries to rollback idx to original position,
but it should not because the entry already has been invalid by
overwriting 'i'. Avoid rollback or commit for entries overwritten.

Signed-off-by: Byungchul Park <byungchul.park@lge.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: akpm@linux-foundation.org
Cc: boqun.feng@gmail.com
Cc: kernel-team@lge.com
Cc: kirill@shutemov.name
Cc: npiggin@gmail.com
Cc: walken@google.com
Cc: willy@infradead.org
Link: http://lkml.kernel.org/r/1502089981-21272-7-git-send-email-byungchul.park@lge.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
include/linux/lockdep.h
include/linux/sched.h
kernel/locking/lockdep.c