bnx2x: Move statistics implementation into semaphores

Commit dff173de84958 ("bnx2x: Fix statistics locking scheme") changed the
bnx2x locking around statistics state into using a mutex - but the lock
is being accessed via a timer which is forbidden.

[If compiled with CONFIG_DEBUG_MUTEXES, logs show a warning about
accessing the mutex in interrupt context]

This moves the implementation into using a semaphore [with size '1']
instead.

Signed-off-by: Yuval Mintz <Yuval.Mintz@qlogic.com>
Signed-off-by: Ariel Elior <Ariel.Elior@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 20 insertions, 11 deletions

diff --git a/drivers/net/ethernet/broadcom/bnx2x/bnx2x.h b/drivers/net/ethernet/broadcom/bnx2x/bnx2x.h
index a3b0f7a0c61e..1f82a04ce01a 100644
--- a/drivers/net/ethernet/broadcom/bnx2x/bnx2x.h
+++ b/drivers/net/ethernet/broadcom/bnx2x/bnx2x.h
@@ -1774,7 +1774,7 @@ struct bnx2x {
         int                     stats_state;
 
         /* used for synchronization of concurrent threads statistics handling */
-        struct mutex            stats_lock;
+        struct semaphore        stats_lock;
 
         /* used by dmae command loader */
         struct dmae_command     stats_dmae;
diff --git a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c
index fd52ce95127e..33501bcddc48 100644
--- a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c
+++ b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c
@@ -12054,7 +12054,7 @@ static int bnx2x_init_bp(struct bnx2x *bp)
         mutex_init(&bp->port.phy_mutex);
         mutex_init(&bp->fw_mb_mutex);
         mutex_init(&bp->drv_info_mutex);
-        mutex_init(&bp->stats_lock);
+        sema_init(&bp->stats_lock, 1);
         bp->drv_info_mng_owner = false;
 
         INIT_DELAYED_WORK(&bp->sp_task, bnx2x_sp_task);
@@ -13690,9 +13690,10 @@ static int bnx2x_eeh_nic_unload(struct bnx2x *bp)
         cancel_delayed_work_sync(&bp->sp_task);
         cancel_delayed_work_sync(&bp->period_task);
 
-        mutex_lock(&bp->stats_lock);
-        bp->stats_state = STATS_STATE_DISABLED;
-        mutex_unlock(&bp->stats_lock);
+        if (!down_timeout(&bp->stats_lock, HZ / 10)) {
+                bp->stats_state = STATS_STATE_DISABLED;
+                up(&bp->stats_lock);
+        }
 
         bnx2x_save_statistics(bp);
 
diff --git a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_stats.c b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_stats.c
index 266b055c2360..69d699f0730a 100644
--- a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_stats.c
+++ b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_stats.c
@@ -1372,19 +1372,23 @@ void bnx2x_stats_handle(struct bnx2x *bp, enum bnx2x_stats_event event)
          * that context in case someone is in the middle of a transition.
          * For other events, wait a bit until lock is taken.
          */
-        if (!mutex_trylock(&bp->stats_lock)) {
+        if (down_trylock(&bp->stats_lock)) {
                 if (event == STATS_EVENT_UPDATE)
                         return;
 
                 DP(BNX2X_MSG_STATS,
                    "Unlikely stats' lock contention [event %d]\n", event);
-                mutex_lock(&bp->stats_lock);
+                if (unlikely(down_timeout(&bp->stats_lock, HZ / 10))) {
+                        BNX2X_ERR("Failed to take stats lock [event %d]\n",
+                                  event);
+                        return;
+                }
         }
 
         bnx2x_stats_stm[state][event].action(bp);
         bp->stats_state = bnx2x_stats_stm[state][event].next_state;
 
-        mutex_unlock(&bp->stats_lock);
+        up(&bp->stats_lock);
 
         if ((event != STATS_EVENT_UPDATE) || netif_msg_timer(bp))
                 DP(BNX2X_MSG_STATS, "state %d -> event %d -> state %d\n",
@@ -1970,7 +1974,11 @@ int bnx2x_stats_safe_exec(struct bnx2x *bp,
         /* Wait for statistics to end [while blocking further requests],
          * then run supplied function 'safely'.
          */
-        mutex_lock(&bp->stats_lock);
+        rc = down_timeout(&bp->stats_lock, HZ / 10);
+        if (unlikely(rc)) {
+                BNX2X_ERR("Failed to take statistics lock for safe execution\n");
+                goto out_no_lock;
+        }
 
         bnx2x_stats_comp(bp);
         while (bp->stats_pending && cnt--)
@@ -1988,7 +1996,7 @@ out:
         /* No need to restart statistics - if they're enabled, the timer
          * will restart the statistics.
          */
-        mutex_unlock(&bp->stats_lock);
-
+        up(&bp->stats_lock);
+out_no_lock:
         return rc;
 }