Author: hselasky
Date: Fri Jan 27 08:32:50 2017
New Revision: 312865
URL: https://svnweb.freebsd.org/changeset/base/312865
Log:
Enforce reading the consumer and producer counters once to ensure
consistent return values from the mlx5e_sq_has_room_for()
function. The two counters are incremented by different threads under
different locks.
MFC after: 1 week
Sponsored by: Mellanox Technologies
Modified:
head/sys/dev/mlx5/mlx5_en/en.h
Modified: head/sys/dev/mlx5/mlx5_en/en.h
==============================================================================
--- head/sys/dev/mlx5/mlx5_en/en.h Fri Jan 27 08:30:43 2017
(r312864)
+++ head/sys/dev/mlx5/mlx5_en/en.h Fri Jan 27 08:32:50 2017
(r312865)
@@ -546,8 +546,10 @@ struct mlx5e_sq {
static inline bool
mlx5e_sq_has_room_for(struct mlx5e_sq *sq, u16 n)
{
- return ((sq->wq.sz_m1 & (sq->cc - sq->pc)) >= n ||
- sq->cc == sq->pc);
+ u16 cc = sq->cc;
+ u16 pc = sq->pc;
+
+ return ((sq->wq.sz_m1 & (cc - pc)) >= n || cc == pc);
}
struct mlx5e_channel {
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