56 lines
2.0 KiB
Diff
56 lines
2.0 KiB
Diff
From: Hiroaki SHIMODA <shimoda.hiroaki@gmail.com>
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Date: Wed, 30 May 2012 12:25:37 +0000
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Subject: bql: Avoid possible inconsistent calculation.
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commit 914bec1011a25f65cdc94988a6f974bfb9a3c10d upstream.
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dql->num_queued could change while processing dql_completed().
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To provide consistent calculation, added an on stack variable.
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Signed-off-by: Hiroaki SHIMODA <shimoda.hiroaki@gmail.com>
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Cc: Tom Herbert <therbert@google.com>
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Cc: Eric Dumazet <eric.dumazet@gmail.com>
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Cc: Denys Fedoryshchenko <denys@visp.net.lb>
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Signed-off-by: Eric Dumazet <edumazet@google.com>
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Signed-off-by: David S. Miller <davem@davemloft.net>
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---
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lib/dynamic_queue_limits.c | 12 +++++++-----
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1 file changed, 7 insertions(+), 5 deletions(-)
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diff --git a/lib/dynamic_queue_limits.c b/lib/dynamic_queue_limits.c
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index 0fafa77..0777c5a 100644
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--- a/lib/dynamic_queue_limits.c
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+++ b/lib/dynamic_queue_limits.c
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@@ -17,16 +17,18 @@
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void dql_completed(struct dql *dql, unsigned int count)
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{
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unsigned int inprogress, prev_inprogress, limit;
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- unsigned int ovlimit, completed;
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+ unsigned int ovlimit, completed, num_queued;
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bool all_prev_completed;
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+ num_queued = ACCESS_ONCE(dql->num_queued);
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+
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/* Can't complete more than what's in queue */
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- BUG_ON(count > dql->num_queued - dql->num_completed);
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+ BUG_ON(count > num_queued - dql->num_completed);
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completed = dql->num_completed + count;
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limit = dql->limit;
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- ovlimit = POSDIFF(dql->num_queued - dql->num_completed, limit);
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- inprogress = dql->num_queued - completed;
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+ ovlimit = POSDIFF(num_queued - dql->num_completed, limit);
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+ inprogress = num_queued - completed;
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prev_inprogress = dql->prev_num_queued - dql->num_completed;
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all_prev_completed = AFTER_EQ(completed, dql->prev_num_queued);
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@@ -106,7 +108,7 @@ void dql_completed(struct dql *dql, unsigned int count)
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dql->prev_ovlimit = ovlimit;
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dql->prev_last_obj_cnt = dql->last_obj_cnt;
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dql->num_completed = completed;
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- dql->prev_num_queued = dql->num_queued;
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+ dql->prev_num_queued = num_queued;
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}
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EXPORT_SYMBOL(dql_completed);
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