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| author | Andreas Gruenbacher <agruenba@redhat.com> | 2019-05-17 19:18:43 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-05-31 06:47:11 -0700 |
| commit | 11db0310d31de4deb24d06af043ae75d99d938ba (patch) | |
| tree | e836f1f4b577d90b01052eff8f02e0c362a15839 | |
| parent | cf3780155df66a2df28a0f894d524ea765385f08 (diff) | |
| download | linux-stable-11db0310d31de4deb24d06af043ae75d99d938ba.tar.gz linux-stable-11db0310d31de4deb24d06af043ae75d99d938ba.tar.bz2 linux-stable-11db0310d31de4deb24d06af043ae75d99d938ba.zip | |
gfs2: Fix sign extension bug in gfs2_update_stats
commit 5a5ec83d6ac974b12085cd99b196795f14079037 upstream.
Commit 4d207133e9c3 changed the types of the statistic values in struct
gfs2_lkstats from s64 to u64. Because of that, what should be a signed
value in gfs2_update_stats turned into an unsigned value. When shifted
right, we end up with a large positive value instead of a small negative
value, which results in an incorrect variance estimate.
Fixes: 4d207133e9c3 ("gfs2: Make statistics unsigned, suitable for use with do_div()")
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Cc: stable@vger.kernel.org # v4.4+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | fs/gfs2/lock_dlm.c | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/fs/gfs2/lock_dlm.c b/fs/gfs2/lock_dlm.c index 65f33a0ac190..6f5c033fe4b5 100644 --- a/fs/gfs2/lock_dlm.c +++ b/fs/gfs2/lock_dlm.c @@ -31,9 +31,10 @@ * @delta is the difference between the current rtt sample and the * running average srtt. We add 1/8 of that to the srtt in order to * update the current srtt estimate. The variance estimate is a bit - * more complicated. We subtract the abs value of the @delta from - * the current variance estimate and add 1/4 of that to the running - * total. + * more complicated. We subtract the current variance estimate from + * the abs value of the @delta and add 1/4 of that to the running + * total. That's equivalent to 3/4 of the current variance + * estimate plus 1/4 of the abs of @delta. * * Note that the index points at the array entry containing the smoothed * mean value, and the variance is always in the following entry @@ -49,7 +50,7 @@ static inline void gfs2_update_stats(struct gfs2_lkstats *s, unsigned index, s64 delta = sample - s->stats[index]; s->stats[index] += (delta >> 3); index++; - s->stats[index] += ((abs(delta) - s->stats[index]) >> 2); + s->stats[index] += (s64)(abs(delta) - s->stats[index]) >> 2; } /** |