| From | Greg Kroah-Hartman <> | Subject | [ 018/187] bql: Avoid possible inconsistent calculation. | Date | Thu, 12 Jul 2012 15:32:54 -0700 |
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From: Greg KH <gregkh@linuxfoundation.org>
3.4-stable review patch. If anyone has any objections, please let me know.
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From: Hiroaki SHIMODA <shimoda.hiroaki@gmail.com>
[ Upstream commit 914bec1011a25f65cdc94988a6f974bfb9a3c10d ]
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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- lib/dynamic_queue_limits.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-)
--- 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, unsi 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);
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