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authorLinus Torvalds <torvalds@linux-foundation.org>2009-12-11 20:48:21 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2009-12-11 20:48:21 -0800
commit1e57c2186fc204ecd5e47f279d00eba3c3db245c (patch)
treeaad97e94afe668b2fe734ef28536627ec00860d8
parent756300983f11a1c6f9457d6d8f57354e0f0fe8d4 (diff)
parentea5b41f9d595be354f7a50e56b28c2d72e6e88a5 (diff)
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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
* '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
-rw-r--r--Documentation/lockstat.txt12
-rw-r--r--kernel/futex.c10
-rw-r--r--kernel/lockdep.c16
3 files changed, 32 insertions, 6 deletions
diff --git a/Documentation/lockstat.txt b/Documentation/lockstat.txt
index 9cb9138f7a7..65f4c795015 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 fb65e822fc4..d73ef1f3e55 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 f5dcd36d315..4f8df01dbe5 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;