From 914bec1011a25f65cdc94988a6f974bfb9a3c10d Mon Sep 17 00:00:00 2001 From: Hiroaki SHIMODA Date: Wed, 30 May 2012 12:25:37 +0000 Subject: [PATCH] bql: Avoid possible inconsistent calculation. dql->num_queued could change while processing dql_completed(). To provide consistent calculation, added an on stack variable. Signed-off-by: Hiroaki SHIMODA Cc: Tom Herbert Cc: Eric Dumazet Cc: Denys Fedoryshchenko Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- lib/dynamic_queue_limits.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/lib/dynamic_queue_limits.c b/lib/dynamic_queue_limits.c index 0fafa77f4036..0777c5a45fa0 100644 --- a/lib/dynamic_queue_limits.c +++ b/lib/dynamic_queue_limits.c @@ -17,16 +17,18 @@ void dql_completed(struct dql *dql, unsigned int count) { unsigned int inprogress, prev_inprogress, limit; - unsigned int ovlimit, completed; + unsigned int ovlimit, completed, num_queued; bool all_prev_completed; + num_queued = ACCESS_ONCE(dql->num_queued); + /* Can't complete more than what's in queue */ - BUG_ON(count > dql->num_queued - dql->num_completed); + BUG_ON(count > num_queued - dql->num_completed); completed = dql->num_completed + count; limit = dql->limit; - ovlimit = POSDIFF(dql->num_queued - dql->num_completed, limit); - inprogress = dql->num_queued - completed; + ovlimit = POSDIFF(num_queued - dql->num_completed, limit); + inprogress = num_queued - completed; prev_inprogress = dql->prev_num_queued - dql->num_completed; all_prev_completed = AFTER_EQ(completed, dql->prev_num_queued); @@ -106,7 +108,7 @@ void dql_completed(struct dql *dql, unsigned int count) dql->prev_ovlimit = ovlimit; dql->prev_last_obj_cnt = dql->last_obj_cnt; dql->num_completed = completed; - dql->prev_num_queued = dql->num_queued; + dql->prev_num_queued = num_queued; } EXPORT_SYMBOL(dql_completed); -- 2.30.2