bnx2x: Protect a SM state change

Bug fix: Protect the statistics state machine state update with a
spinlock.  Otherwise there was a race condition that would cause the
statistics to stay enabled despite the fact that they were disabled in
the LINK_DOWN event handler.

Signed-off-by: Vladislav Zolotarov <vladz@broadcom.com>
Signed-off-by: Dmitry Kravkov <dmitry@broadcom.com>
Signed-off-by: Eilon Greenstein <eilong@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 11 insertions, 4 deletions

diff --git a/drivers/net/bnx2x.h b/drivers/net/bnx2x.h
index 8bd23687c530..bb0872a63315 100644
--- a/drivers/net/bnx2x.h
+++ b/drivers/net/bnx2x.h
@@ -1062,6 +1062,10 @@ struct bnx2x {
 
         /* used to synchronize stats collecting */
         int                     stats_state;
+
+        /* used for synchronization of concurrent threads statistics handling */
+        spinlock_t              stats_lock;
+
         /* used by dmae command loader */
         struct dmae_command     stats_dmae;
         int                     executer_idx;
diff --git a/drivers/net/bnx2x_main.c b/drivers/net/bnx2x_main.c
index 57ff5b3bcce6..3dc876ce6e1f 100644
--- a/drivers/net/bnx2x_main.c
+++ b/drivers/net/bnx2x_main.c
@@ -4849,16 +4849,18 @@ static const struct {
 
 static void bnx2x_stats_handle(struct bnx2x *bp, enum bnx2x_stats_event event)
 {
-        enum bnx2x_stats_state state = bp->stats_state;
+        enum bnx2x_stats_state state;
 
         if (unlikely(bp->panic))
                 return;
 
-        bnx2x_stats_stm[state][event].action(bp);
+        /* Protect a state change flow */
+        spin_lock_bh(&bp->stats_lock);
+        state = bp->stats_state;
         bp->stats_state = bnx2x_stats_stm[state][event].next_state;
+        spin_unlock_bh(&bp->stats_lock);
 
-        /* Make sure the state has been "changed" */
-        smp_wmb();
+        bnx2x_stats_stm[state][event].action(bp);
 
         if ((event != STATS_EVENT_UPDATE) || netif_msg_timer(bp))
                 DP(BNX2X_MSG_STATS, "state %d -> event %d -> state %d\n",
@@ -9908,6 +9910,7 @@ static int __devinit bnx2x_init_bp(struct bnx2x *bp)
 
         mutex_init(&bp->port.phy_mutex);
         mutex_init(&bp->fw_mb_mutex);
+        spin_lock_init(&bp->stats_lock);
 #ifdef BCM_CNIC
         mutex_init(&bp->cnic_mutex);
 #endif