path: root/block
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authorAnatol Pomozov <anatol.pomozov@gmail.com>2013-09-22 12:43:47 -0600
committerJens Axboe <axboe@kernel.dk>2013-09-22 12:43:47 -0600
commitf3cff25f05f2ac29b2ee355e611b0657482f6f1d (patch)
tree8a06c59f0970a8bd4be2939792fc88ffddc39e62 /block
parent75afb352991ff1cd3cf5955bfe611de6d83a0c87 (diff)
cfq: explicitly use 64bit divide operation for 64bit arguments
'samples' is 64bit operant, but do_div() second parameter is 32. do_div silently truncates high 32 bits and calculated result is invalid. In case if low 32bit of 'samples' are zeros then do_div() produces kernel crash. Signed-off-by: Anatol Pomozov <anatol.pomozov@gmail.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
1 files changed, 1 insertions, 1 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index f0468e252ee4..51e06ea06a2e 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -1803,7 +1803,7 @@ static u64 cfqg_prfill_avg_queue_size(struct seq_file *sf,
if (samples) {
v = blkg_stat_read(&cfqg->stats.avg_queue_size_sum);
- do_div(v, samples);
+ v = div64_u64(v, samples);
__blkg_prfill_u64(sf, pd, v);
return 0;