[PATCH] net/tg3: fix race condition in tg3_reset_task_cancel()

[Thinh Tran <thinhtr@linux.vnet.ibm.com>]

during the EEH error injection tests on the 4-port 1 GbE NetXtreme
BCM5719 Gigabit Ethernet PCIe adapter, a race condition was observed in
the process of resetting and setting the driver flag to
TX_RECOVERY_PENDING between tg3_reset_task_cancel() and tg3_tx_recover().
As a result, it occasionally leads to transmit timeouts and the
subsequent disabling of all the driver's interfaces.

[12046.886221] NETDEV WATCHDOG: eth16 (tg3): transmit queue 0 timed out
[12046.886238] WARNING: CPU: 7 PID: 0 at ../net/sched/sch_generic.c:478
   dev_watchdog+0x42c/0x440
[12046.886247] Modules linked in: tg3 libphy nfsv3 nfs_acl .......
 ..........
[12046.886571] tg3 0021:01:00.0 eth16: transmit timed out, resetting
...........
[12046.966175] tg3 0021:01:00.1 eth15: transmit timed out, resetting
...........
[12046.981584] tg3 0021:01:00.2 eth14: transmit timed out, resetting
...........
[12047.056165] tg3 0021:01:00.3 eth13: transmit timed out, resetting


Fixing this issue by taking the spinlock when modifying the driver flag


Fixes: 6c4ca03bd890 ("net/tg3: resolve deadlock in tg3_reset_task() during EEH")


Signed-off-by: Thinh Tran <thinhtr@linux.vnet.ibm.com>
Tested-by: Venkata Sai Duggi <venkata.sai.duggi@ibm.com>

---
 drivers/net/ethernet/broadcom/tg3.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/ethernet/broadcom/tg3.c b/drivers/net/ethernet/broadcom/tg3.c
index 14b311196b8f..f4558762f9de 100644
--- a/drivers/net/ethernet/broadcom/tg3.c
+++ b/drivers/net/ethernet/broadcom/tg3.c
@@ -6507,7 +6507,9 @@ static void tg3_tx_recover(struct tg3 *tp)
 		    "Please report the problem to the driver maintainer "
 		    "and include system chipset information.\n");
 
+	tg3_full_lock(tp, 0);
 	tg3_flag_set(tp, TX_RECOVERY_PENDING);
+	tg3_full_unlock(tp);
 }
 
 static inline u32 tg3_tx_avail(struct tg3_napi *tnapi)
@@ -7210,7 +7212,10 @@ static inline void tg3_reset_task_cancel(struct tg3 *tp)
 {
 	if (test_and_clear_bit(TG3_FLAG_RESET_TASK_PENDING, tp->tg3_flags))
 		cancel_work_sync(&tp->reset_task);
+
+	tg3_full_lock(tp, 0);
 	tg3_flag_clear(tp, TX_RECOVERY_PENDING);
+	tg3_full_unlock(tp);
 }
 
 static int tg3_poll_msix(struct napi_struct *napi, int budget)
-- 
2.25.1