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| author | Steven Rostedt <srostedt@redhat.com> | 2011-04-20 21:42:00 -0400 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2011-04-22 11:06:59 +0200 |
| commit | e0944ee63f7249802be74454cef81c97630ae1cd (patch) | |
| tree | 00c81028ff9b324bdd9106103f043ba26ea54e41 /kernel/lockdep.c | |
| parent | 282b5c2f6f663c008444321fd8fcdd374596046b (diff) | |
| download | lwn-e0944ee63f7249802be74454cef81c97630ae1cd.tar.gz lwn-e0944ee63f7249802be74454cef81c97630ae1cd.zip | |
lockdep: Remove cmpxchg to update nr_chain_hlocks
For some reason nr_chain_hlocks is updated with cmpxchg, but
this is performed inside of the lockdep global "grab_lock()",
which also makes simple modification of this variable atomic.
Remove the cmpxchg logic for updating nr_chain_hlocks and
simplify the code.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20110421014300.727863282@goodmis.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/lockdep.c')
| -rw-r--r-- | kernel/lockdep.c | 14 |
1 files changed, 4 insertions, 10 deletions
diff --git a/kernel/lockdep.c b/kernel/lockdep.c index 27c609f3eae5..63437d065ac8 100644 --- a/kernel/lockdep.c +++ b/kernel/lockdep.c @@ -1973,7 +1973,7 @@ static inline int lookup_chain_cache(struct task_struct *curr, struct list_head *hash_head = chainhashentry(chain_key); struct lock_chain *chain; struct held_lock *hlock_curr, *hlock_next; - int i, j, n, cn; + int i, j; if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) return 0; @@ -2033,15 +2033,9 @@ cache_hit: } i++; chain->depth = curr->lockdep_depth + 1 - i; - cn = nr_chain_hlocks; - while (cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS) { - n = cmpxchg(&nr_chain_hlocks, cn, cn + chain->depth); - if (n == cn) - break; - cn = n; - } - if (likely(cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) { - chain->base = cn; + if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) { + chain->base = nr_chain_hlocks; + nr_chain_hlocks += chain->depth; for (j = 0; j < chain->depth - 1; j++, i++) { int lock_id = curr->held_locks[i].class_idx - 1; chain_hlocks[chain->base + j] = lock_id; |