diff options
| -rw-r--r-- | Documentation/lockstat.txt | 12 | ||||
| -rw-r--r-- | kernel/futex.c | 10 | ||||
| -rw-r--r-- | kernel/lockdep.c | 16 |
3 files changed, 32 insertions, 6 deletions
diff --git a/Documentation/lockstat.txt b/Documentation/lockstat.txt index 9cb9138f7a79..65f4c795015d 100644 --- a/Documentation/lockstat.txt +++ b/Documentation/lockstat.txt @@ -62,8 +62,20 @@ applicable). It also tracks 4 contention points per class. A contention point is a call site that had to wait on lock acquisition. + - CONFIGURATION + +Lock statistics are enabled via CONFIG_LOCK_STATS. + - USAGE +Enable collection of statistics: + +# echo 1 >/proc/sys/kernel/lock_stat + +Disable collection of statistics: + +# echo 0 >/proc/sys/kernel/lock_stat + Look at the current lock statistics: ( line numbers not part of actual output, done for clarity in the explanation diff --git a/kernel/futex.c b/kernel/futex.c index fb65e822fc41..d73ef1f3e55d 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -304,8 +304,14 @@ void put_futex_key(int fshared, union futex_key *key) */ static int fault_in_user_writeable(u32 __user *uaddr) { - int ret = get_user_pages(current, current->mm, (unsigned long)uaddr, - 1, 1, 0, NULL, NULL); + struct mm_struct *mm = current->mm; + int ret; + + down_read(&mm->mmap_sem); + ret = get_user_pages(current, mm, (unsigned long)uaddr, + 1, 1, 0, NULL, NULL); + up_read(&mm->mmap_sem); + return ret < 0 ? ret : 0; } diff --git a/kernel/lockdep.c b/kernel/lockdep.c index f5dcd36d3151..4f8df01dbe51 100644 --- a/kernel/lockdep.c +++ b/kernel/lockdep.c @@ -168,7 +168,7 @@ static void lock_time_inc(struct lock_time *lt, u64 time) if (time > lt->max) lt->max = time; - if (time < lt->min || !lt->min) + if (time < lt->min || !lt->nr) lt->min = time; lt->total += time; @@ -177,8 +177,15 @@ static void lock_time_inc(struct lock_time *lt, u64 time) static inline void lock_time_add(struct lock_time *src, struct lock_time *dst) { - dst->min += src->min; - dst->max += src->max; + if (!src->nr) + return; + + if (src->max > dst->max) + dst->max = src->max; + + if (src->min < dst->min || !dst->nr) + dst->min = src->min; + dst->total += src->total; dst->nr += src->nr; } @@ -379,7 +386,8 @@ static int save_trace(struct stack_trace *trace) * complete trace that maxes out the entries provided will be reported * as incomplete, friggin useless </rant> */ - if (trace->entries[trace->nr_entries-1] == ULONG_MAX) + if (trace->nr_entries != 0 && + trace->entries[trace->nr_entries-1] == ULONG_MAX) trace->nr_entries--; trace->max_entries = trace->nr_entries; |