ixgbe: only process one ixgbe_watchdog_task at a time.

Processing multiple ixgbe_watchdog_task calls may cause
the link_up variable and IXGBE_FLAG_NEED_LINK_UPDATE flag
to be set incorrectly.  In the worse case this is causing
the netif_carrier_off to be called inappropriately which
results in an interface that can't be brought up.

Although schedule_work() will only schedule the task if
it is not already on the work queue the WORK_STRUCT_PENDING
bits are cleared just before calling the work function.
This allows WORK_STRUCT_PENDING to be cleared, the work
function to start and meanwhile schedule another task.

This patch adds a mutex to the watchdog task. This bug is
actualized by changing DCB settings or doing extended
cable pull or reset tests.

Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 9 deletions

diff --git a/drivers/net/ixgbe/ixgbe.h b/drivers/net/ixgbe/ixgbe.h
index e576fb4740bc..55a319e3a57a 100644
--- a/drivers/net/ixgbe/ixgbe.h
+++ b/drivers/net/ixgbe/ixgbe.h
@@ -341,15 +341,14 @@ struct ixgbe_adapter {
 #define IXGBE_FLAG_VMDQ_ENABLED                 (u32)(1 << 19)
 #define IXGBE_FLAG_FAN_FAIL_CAPABLE             (u32)(1 << 20)
 #define IXGBE_FLAG_NEED_LINK_UPDATE             (u32)(1 << 22)
-#define IXGBE_FLAG_IN_WATCHDOG_TASK             (u32)(1 << 23)
-#define IXGBE_FLAG_IN_SFP_LINK_TASK             (u32)(1 << 24)
-#define IXGBE_FLAG_IN_SFP_MOD_TASK              (u32)(1 << 25)
-#define IXGBE_FLAG_FDIR_HASH_CAPABLE            (u32)(1 << 26)
-#define IXGBE_FLAG_FDIR_PERFECT_CAPABLE         (u32)(1 << 27)
-#define IXGBE_FLAG_FCOE_CAPABLE                 (u32)(1 << 28)
-#define IXGBE_FLAG_FCOE_ENABLED                 (u32)(1 << 29)
-#define IXGBE_FLAG_SRIOV_CAPABLE                (u32)(1 << 30)
-#define IXGBE_FLAG_SRIOV_ENABLED                (u32)(1 << 31)
+#define IXGBE_FLAG_IN_SFP_LINK_TASK             (u32)(1 << 23)
+#define IXGBE_FLAG_IN_SFP_MOD_TASK              (u32)(1 << 24)
+#define IXGBE_FLAG_FDIR_HASH_CAPABLE            (u32)(1 << 25)
+#define IXGBE_FLAG_FDIR_PERFECT_CAPABLE         (u32)(1 << 26)
+#define IXGBE_FLAG_FCOE_CAPABLE                 (u32)(1 << 27)
+#define IXGBE_FLAG_FCOE_ENABLED                 (u32)(1 << 28)
+#define IXGBE_FLAG_SRIOV_CAPABLE                (u32)(1 << 29)
+#define IXGBE_FLAG_SRIOV_ENABLED                (u32)(1 << 30)
 
 	u32 flags2;
 #define IXGBE_FLAG2_RSC_CAPABLE                 (u32)(1)