iwmc3200wifi: add a mutex to protect iwm_reset_worker

The patch adds a mutex to protect the iwm_reset_worker against netdev
ndo_open and ndo_stop because all of them call iwm_up and iwm_down in
the implementation. Note the latter two are already protected by
rtnl. So if iwm_reset_worker is not required in the future, the mutex
can also be removed.

Signed-off-by: Zhu Yi <yi.zhu@intel.com>
Signed-off-by: Samuel Ortiz <samuel.ortiz@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

2 files changed, 49 insertions, 6 deletions

diff --git a/drivers/net/wireless/iwmc3200wifi/iwm.h b/drivers/net/wireless/iwmc3200wifi/iwm.h
index 4aa0ad1932ff..77c339f8516c 100644
--- a/drivers/net/wireless/iwmc3200wifi/iwm.h
+++ b/drivers/net/wireless/iwmc3200wifi/iwm.h
@@ -288,6 +288,7 @@ struct iwm_priv {
         u8 *eeprom;
         struct timer_list watchdog;
         struct work_struct reset_worker;
+        struct mutex mutex;
         struct rfkill *rfkill;
 
         char private[0] __attribute__((__aligned__(NETDEV_ALIGN)));
diff --git a/drivers/net/wireless/iwmc3200wifi/main.c b/drivers/net/wireless/iwmc3200wifi/main.c
index 4d3c423d8ffc..8be206d58222 100644
--- a/drivers/net/wireless/iwmc3200wifi/main.c
+++ b/drivers/net/wireless/iwmc3200wifi/main.c
@@ -112,6 +112,9 @@ static void iwm_statistics_request(struct work_struct *work)
         iwm_send_umac_stats_req(iwm, 0);
 }
 
+int __iwm_up(struct iwm_priv *iwm);
+int __iwm_down(struct iwm_priv *iwm);
+
 static void iwm_reset_worker(struct work_struct *work)
 {
         struct iwm_priv *iwm;
@@ -120,6 +123,19 @@ static void iwm_reset_worker(struct work_struct *work)
 
         iwm = container_of(work, struct iwm_priv, reset_worker);
 
+        /*
+         * XXX: The iwm->mutex is introduced purely for this reset work,
+         * because the other users for iwm_up and iwm_down are only netdev
+         * ndo_open and ndo_stop which are already protected by rtnl.
+         * Please remove iwm->mutex together if iwm_reset_worker() is not
+         * required in the future.
+         */
+        if (!mutex_trylock(&iwm->mutex)) {
+                IWM_WARN(iwm, "We are in the middle of interface bringing "
+                         "UP/DOWN. Skip driver resetting.\n");
+                return;
+        }
+
         if (iwm->umac_profile_active) {
                 profile = kmalloc(sizeof(struct iwm_umac_profile), GFP_KERNEL);
                 if (profile)
@@ -128,10 +144,10 @@ static void iwm_reset_worker(struct work_struct *work)
                         IWM_ERR(iwm, "Couldn't alloc memory for profile\n");
         }
 
-        iwm_down(iwm);
+        __iwm_down(iwm);
 
         while (retry++ < 3) {
-                ret = iwm_up(iwm);
+                ret = __iwm_up(iwm);
                 if (!ret)
                         break;
 
@@ -142,7 +158,7 @@ static void iwm_reset_worker(struct work_struct *work)
                 IWM_WARN(iwm, "iwm_up() failed: %d\n", ret);
 
                 kfree(profile);
-                return;
+                goto out;
         }
 
         if (profile) {
@@ -151,6 +167,9 @@ static void iwm_reset_worker(struct work_struct *work)
                 iwm_send_mlme_profile(iwm);
                 kfree(profile);
         }
+
+ out:
+        mutex_unlock(&iwm->mutex);
 }
 
 static void iwm_watchdog(unsigned long data)
@@ -215,6 +234,7 @@ int iwm_priv_init(struct iwm_priv *iwm)
         init_timer(&iwm->watchdog);
         iwm->watchdog.function = iwm_watchdog;
         iwm->watchdog.data = (unsigned long)iwm;
+        mutex_init(&iwm->mutex);
 
         return 0;
 }
@@ -476,7 +496,7 @@ void iwm_link_off(struct iwm_priv *iwm)
 
         iwm_rx_free(iwm);
 
-        cancel_delayed_work(&iwm->stats_request);
+        cancel_delayed_work_sync(&iwm->stats_request);
         memset(wstats, 0, sizeof(struct iw_statistics));
         wstats->qual.updated = IW_QUAL_ALL_INVALID;
 
@@ -521,7 +541,7 @@ static int iwm_channels_init(struct iwm_priv *iwm)
         return 0;
 }
 
-int iwm_up(struct iwm_priv *iwm)
+int __iwm_up(struct iwm_priv *iwm)
 {
         int ret;
         struct iwm_notif *notif_reboot, *notif_ack = NULL;
@@ -657,7 +677,18 @@ int iwm_up(struct iwm_priv *iwm)
         return -EIO;
 }
 
-int iwm_down(struct iwm_priv *iwm)
+int iwm_up(struct iwm_priv *iwm)
+{
+        int ret;
+
+        mutex_lock(&iwm->mutex);
+        ret = __iwm_up(iwm);
+        mutex_unlock(&iwm->mutex);
+
+        return ret;
+}
+
+int __iwm_down(struct iwm_priv *iwm)
 {
         int ret;
 
@@ -688,3 +719,14 @@ int iwm_down(struct iwm_priv *iwm)
 
         return 0;
 }
+
+int iwm_down(struct iwm_priv *iwm)
+{
+        int ret;
+
+        mutex_lock(&iwm->mutex);
+        ret = __iwm_down(iwm);
+        mutex_unlock(&iwm->mutex);
+
+        return ret;
+}