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authorByungchul Park <byungchul.park@lge.com>2017-08-14 16:00:52 +0900
committerIngo Molnar <mingo@kernel.org>2017-08-14 12:52:17 +0200
commit907dc16d7e23ec81a126c9585435494fa1b3a4b7 (patch)
tree31b53da542b0fa6cb863c06a39daeed055372acb /kernel/locking
parenta10b5c564741cd3b6708f085a1fa892b63c2063d (diff)
downloadlinux-907dc16d7e23ec81a126c9585435494fa1b3a4b7.tar.bz2
locking/lockdep: Fix the rollback and overwrite detection logic in crossrelease
As Boqun Feng pointed out, current->hist_id should be aligned with the latest valid xhlock->hist_id so that hist_id_save[] storing current->hist_id can be comparable with xhlock->hist_id. Fix it. Additionally, the condition for overwrite-detection should be the opposite. Fix the code and the comments as well. <- direction to visit hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh (h: history) ^^ ^ || start from here |previous entry current entry Reported-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Byungchul Park <byungchul.park@lge.com> 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: kernel-team@lge.com Cc: kirill@shutemov.name Cc: linux-mm@kvack.org Cc: npiggin@gmail.com Cc: walken@google.com Cc: willy@infradead.org Link: http://lkml.kernel.org/r/1502694052-16085-3-git-send-email-byungchul.park@lge.com [ Improve the comments some more. ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/locking')
-rw-r--r--kernel/locking/lockdep.c12
1 files changed, 6 insertions, 6 deletions
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 257931e2fbbe..66011c9f5df3 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -4853,7 +4853,7 @@ static void add_xhlock(struct held_lock *hlock)
/* Initialize hist_lock's members */
xhlock->hlock = *hlock;
- xhlock->hist_id = current->hist_id++;
+ xhlock->hist_id = ++current->hist_id;
xhlock->trace.nr_entries = 0;
xhlock->trace.max_entries = MAX_XHLOCK_TRACE_ENTRIES;
@@ -5029,12 +5029,12 @@ static void commit_xhlocks(struct cross_lock *xlock)
break;
/*
- * Filter out the cases that the ring buffer was
- * overwritten and the previous entry has a bigger
- * hist_id than the following one, which is impossible
- * otherwise.
+ * Filter out the cases where the ring buffer was
+ * overwritten and the current entry has a bigger
+ * hist_id than the previous one, which is impossible
+ * otherwise:
*/
- if (unlikely(before(xhlock->hist_id, prev_hist_id)))
+ if (unlikely(before(prev_hist_id, xhlock->hist_id)))
break;
prev_hist_id = xhlock->hist_id;