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| author | Corrado Zoccolo <czoccolo@gmail.com> | 2009-10-05 08:49:23 +0200 |
|---|---|---|
| committer | Jens Axboe <jens.axboe@oracle.com> | 2009-10-05 11:03:55 +0200 |
| commit | 48e025e63ac908ed6ec5394a294f4ecd510a7476 (patch) | |
| tree | 49828c00687c810627f00430dd56ce9901537fc9 /block/cfq-iosched.c | |
| parent | 30996f40bffe73f05abb92a4cec254befa8cecf7 (diff) | |
| download | lwn-48e025e63ac908ed6ec5394a294f4ecd510a7476.tar.gz lwn-48e025e63ac908ed6ec5394a294f4ecd510a7476.zip | |
cfq-iosched: fix possible problem with jiffies wraparound
The RR service tree is indexed by a key that is relative to current jiffies.
This can cause problems on jiffies wraparound.
The patch fixes it using time_before comparison, and changing
the add_front path to use a relative number, too.
Signed-off-by: Corrado Zoccolo <czoccolo@gmail.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'block/cfq-iosched.c')
| -rw-r--r-- | block/cfq-iosched.c | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index e7f9e4e3a270..ae14cbaf9d0e 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -512,8 +512,11 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq, rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies; rb_key += cfqq->slice_resid; cfqq->slice_resid = 0; - } else - rb_key = 0; + } else { + rb_key = -HZ; + __cfqq = cfq_rb_first(&cfqd->service_tree); + rb_key += __cfqq ? __cfqq->rb_key : jiffies; + } if (!RB_EMPTY_NODE(&cfqq->rb_node)) { /* @@ -547,7 +550,7 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq, n = &(*p)->rb_left; else if (cfq_class_idle(cfqq) > cfq_class_idle(__cfqq)) n = &(*p)->rb_right; - else if (rb_key < __cfqq->rb_key) + else if (time_before(rb_key, __cfqq->rb_key)) n = &(*p)->rb_left; else n = &(*p)->rb_right; |