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| author | Hiroaki SHIMODA <shimoda.hiroaki@gmail.com> | 2012-05-30 12:25:37 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2012-05-31 18:18:17 -0400 |
| commit | 914bec1011a25f65cdc94988a6f974bfb9a3c10d (patch) | |
| tree | 2651e473b6f02888b595f215fbfb9710e6e231ff /lib | |
| parent | 25426b794efdc70dde7fd3134dc56fac3e7d562d (diff) | |
| download | lwn-914bec1011a25f65cdc94988a6f974bfb9a3c10d.tar.gz lwn-914bec1011a25f65cdc94988a6f974bfb9a3c10d.zip | |
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>
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/dynamic_queue_limits.c | 12 |
1 files 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); |