ixgbevf: Prevent possible race condition by checking for message

The mailbox interrupt routine might cause a race condition sometimes
and cause a message to be missed.

Signed-off-by: Greg Rose <gregory.v.rose@intel.com>
Tested-by: Sibai Li <sibai.li@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c b/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c
index 891162d..1cad3b6 100644 (file)
--- a/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c
+++ b/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c
@@ -917,31 +917,34 @@ static irqreturn_t ixgbevf_msix_mbx(int irq, void *data)
        struct ixgbe_hw *hw = &adapter->hw;
        u32 eicr;
        u32 msg;
+       bool got_ack = false;
 
        eicr = IXGBE_READ_REG(hw, IXGBE_VTEICS);
        IXGBE_WRITE_REG(hw, IXGBE_VTEICR, eicr);
 
-       if (!hw->mbx.ops.check_for_ack(hw)) {
-               /*
-                * checking for the ack clears the PFACK bit.  Place
-                * it back in the v2p_mailbox cache so that anyone
-                * polling for an ack will not miss it.  Also
-                * avoid the read below because the code to read
-                * the mailbox will also clear the ack bit.  This was
-                * causing lost acks.  Just cache the bit and exit
-                * the IRQ handler.
-                */
-               hw->mbx.v2p_mailbox |= IXGBE_VFMAILBOX_PFACK;
-               goto out;
-       }
+       if (!hw->mbx.ops.check_for_ack(hw))
+               got_ack = true;
 
-       /* Not an ack interrupt, go ahead and read the message */
-       hw->mbx.ops.read(hw, &msg, 1);
+       if (!hw->mbx.ops.check_for_msg(hw)) {
+               hw->mbx.ops.read(hw, &msg, 1);
 
-       if ((msg & IXGBE_MBVFICR_VFREQ_MASK) == IXGBE_PF_CONTROL_MSG)
-               mod_timer(&adapter->watchdog_timer,
-                         round_jiffies(jiffies + 1));
+               if ((msg & IXGBE_MBVFICR_VFREQ_MASK) == IXGBE_PF_CONTROL_MSG)
+                       mod_timer(&adapter->watchdog_timer,
+                                 round_jiffies(jiffies + 1));
 
+               if (msg & IXGBE_VT_MSGTYPE_NACK)
+                       pr_warn("Last Request of type %2.2x to PF Nacked\n",
+                               msg & 0xFF);
+               goto out;
+       }
+
+       /*
+        * checking for the ack clears the PFACK bit.  Place
+        * it back in the v2p_mailbox cache so that anyone
+        * polling for an ack will not miss it
+        */
+       if (got_ack)
+               hw->mbx.v2p_mailbox |= IXGBE_VFMAILBOX_PFACK;
 out:
        return IRQ_HANDLED;
 }