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Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

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* 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  lockdep: Avoid out of bounds array reference in save_trace()
  futex: Take mmap_sem for get_user_pages in fault_in_user_writeable
  lockstat: Add usage info to Documentation/lockstat.txt
  lockstat: Fix min, max times in /proc/lock_stats
This commit is contained in:
Linus Torvalds 2009-12-11 20:48:21 -08:00
commit 1e57c2186f
3 changed files with 32 additions and 6 deletions
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12
Documentation/lockstat.txt
View File

@ -62,8 +62,20 @@ applicable).
It also tracks 4 contention points per class. A contention point is a call site It also tracks 4 contention points per class. A contention point is a call site
that had to wait on lock acquisition. that had to wait on lock acquisition.
- CONFIGURATION
Lock statistics are enabled via CONFIG_LOCK_STATS.
- USAGE - 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: Look at the current lock statistics:
( line numbers not part of actual output, done for clarity in the explanation ( line numbers not part of actual output, done for clarity in the explanation

10
kernel/futex.c
View File

@ -304,8 +304,14 @@ void put_futex_key(int fshared, union futex_key *key)
*/ */
static int fault_in_user_writeable(u32 __user *uaddr) static int fault_in_user_writeable(u32 __user *uaddr)
{ {
int ret = get_user_pages(current, current->mm, (unsigned long)uaddr, struct mm_struct *mm = current->mm;
1, 1, 0, NULL, NULL); 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; return ret < 0 ? ret : 0;
} }

16
kernel/lockdep.c
View File

@ -168,7 +168,7 @@ static void lock_time_inc(struct lock_time *lt, u64 time)
if (time > lt->max) if (time > lt->max)
lt->max = time; lt->max = time;
if (time < lt->min || !lt->min) if (time < lt->min || !lt->nr)
lt->min = time; lt->min = time;
lt->total += 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) static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
{ {
dst->min += src->min; if (!src->nr)
dst->max += src->max; 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->total += src->total;
dst->nr += src->nr; 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 * complete trace that maxes out the entries provided will be reported
* as incomplete, friggin useless </rant> * 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->nr_entries--;
trace->max_entries = trace->nr_entries; trace->max_entries = trace->nr_entries;