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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 <shimoda.hiroaki@gmail.com>
Cc: Tom Herbert <therbert@google.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Denys Fedoryshchenko <denys@visp.net.lb>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Hiroaki SHIMODA 2012-05-30 12:25:37 +00:00 committed by David S. Miller
parent 25426b794e
commit 914bec1011
1 changed files with 7 additions and 5 deletions
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12
lib/dynamic_queue_limits.c
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@ -17,16 +17,18 @@
void dql_completed(struct dql *dql, unsigned int count) void dql_completed(struct dql *dql, unsigned int count)
{ {
unsigned int inprogress, prev_inprogress, limit; unsigned int inprogress, prev_inprogress, limit;
unsigned int ovlimit, completed; unsigned int ovlimit, completed, num_queued;
bool all_prev_completed; bool all_prev_completed;
num_queued = ACCESS_ONCE(dql->num_queued);
/* Can't complete more than what's in queue */ /* 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; completed = dql->num_completed + count;
limit = dql->limit; limit = dql->limit;
ovlimit = POSDIFF(dql->num_queued - dql->num_completed, limit); ovlimit = POSDIFF(num_queued - dql->num_completed, limit);
inprogress = dql->num_queued - completed; inprogress = num_queued - completed;
prev_inprogress = dql->prev_num_queued - dql->num_completed; prev_inprogress = dql->prev_num_queued - dql->num_completed;
all_prev_completed = AFTER_EQ(completed, dql->prev_num_queued); 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_ovlimit = ovlimit;
dql->prev_last_obj_cnt = dql->last_obj_cnt; dql->prev_last_obj_cnt = dql->last_obj_cnt;
dql->num_completed = completed; dql->num_completed = completed;
dql->prev_num_queued = dql->num_queued; dql->prev_num_queued = num_queued;
} }
EXPORT_SYMBOL(dql_completed); EXPORT_SYMBOL(dql_completed);