The following commit has been merged in the linux branch: commit 3365e7798760dc6c190a9bbb0945a38f02625438 Author: Peter Zijlstra a.p.zijlstra@chello.nl Date: Fri Oct 9 10:12:41 2009 +0200
lockdep: Use cpu_clock() for lockstat
Some tracepoint magic (TRACE_EVENT(lock_acquired)) relies on the fact that lock hold times are positive and uses div64 on that. That triggered a build warning on MIPS, and probably causes bad output in certain circumstances as well.
Make it truly positive.
Reported-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Peter Zijlstra a.p.zijlstra@chello.nl LKML-Reference: 1254818502.21044.112.camel@laptop Signed-off-by: Ingo Molnar mingo@elte.hu
diff --git a/kernel/lockdep.c b/kernel/lockdep.c index 3815ac1..9af5672 100644 --- a/kernel/lockdep.c +++ b/kernel/lockdep.c @@ -142,6 +142,11 @@ static inline struct lock_class *hlock_class(struct held_lock *hlock) #ifdef CONFIG_LOCK_STAT static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], lock_stats);
+static inline u64 lockstat_clock(void) +{ + return cpu_clock(smp_processor_id()); +} + static int lock_point(unsigned long points[], unsigned long ip) { int i; @@ -158,7 +163,7 @@ static int lock_point(unsigned long points[], unsigned long ip) return i; }
-static void lock_time_inc(struct lock_time *lt, s64 time) +static void lock_time_inc(struct lock_time *lt, u64 time) { if (time > lt->max) lt->max = time; @@ -234,12 +239,12 @@ static void put_lock_stats(struct lock_class_stats *stats) static void lock_release_holdtime(struct held_lock *hlock) { struct lock_class_stats *stats; - s64 holdtime; + u64 holdtime;
if (!lock_stat) return;
- holdtime = sched_clock() - hlock->holdtime_stamp; + holdtime = lockstat_clock() - hlock->holdtime_stamp;
stats = get_lock_stats(hlock_class(hlock)); if (hlock->read) @@ -2792,7 +2797,7 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass, hlock->references = references; #ifdef CONFIG_LOCK_STAT hlock->waittime_stamp = 0; - hlock->holdtime_stamp = sched_clock(); + hlock->holdtime_stamp = lockstat_clock(); #endif
if (check == 2 && !mark_irqflags(curr, hlock)) @@ -3322,7 +3327,7 @@ found_it: if (hlock->instance != lock) return;
- hlock->waittime_stamp = sched_clock(); + hlock->waittime_stamp = lockstat_clock();
contention_point = lock_point(hlock_class(hlock)->contention_point, ip); contending_point = lock_point(hlock_class(hlock)->contending_point, @@ -3345,8 +3350,7 @@ __lock_acquired(struct lockdep_map *lock, unsigned long ip) struct held_lock *hlock, *prev_hlock; struct lock_class_stats *stats; unsigned int depth; - u64 now; - s64 waittime = 0; + u64 now, waittime = 0; int i, cpu;
depth = curr->lockdep_depth; @@ -3374,7 +3378,7 @@ found_it:
cpu = smp_processor_id(); if (hlock->waittime_stamp) { - now = sched_clock(); + now = lockstat_clock(); waittime = now - hlock->waittime_stamp; hlock->holdtime_stamp = now; }