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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Alan Brady <alan.brady@intel.com>,
        Andrew Bowers <andrewx.bowers@intel.com>,
        Jeff Kirsher <jeffrey.t.kirsher@intel.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.20 043/352] i40e: prevent overlapping tx_timeout recover
Date:   Mon, 11 Feb 2019 15:14:30 +0100
Message-Id: <20190211141849.050937911@linuxfoundation.org>
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4.20-stable review patch.  If anyone has any objections, please let me know.

------------------

[ Upstream commit d5585b7b6846a6d0f9517afe57be3843150719da ]

If a TX hang occurs, we attempt to recover by incrementally resetting.
If we're starved for CPU time, it's possible the reset doesn't actually
complete (or even fire) before another tx_timeout fires causing us to
fly through the different resets without actually doing them.

This adds a bit to set and check if a timeout recovery is already
pending and, if so, bail out of tx_timeout.  The bit will get cleared at
the end of i40e_rebuild when reset is complete.

Signed-off-by: Alan Brady <alan.brady@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/ethernet/intel/i40e/i40e.h      | 1 +
 drivers/net/ethernet/intel/i40e/i40e_main.c | 5 +++++
 2 files changed, 6 insertions(+)

diff --git a/drivers/net/ethernet/intel/i40e/i40e.h b/drivers/net/ethernet/intel/i40e/i40e.h
index 876cac317e79..8245ff12fd64 100644
--- a/drivers/net/ethernet/intel/i40e/i40e.h
+++ b/drivers/net/ethernet/intel/i40e/i40e.h
@@ -122,6 +122,7 @@ enum i40e_state_t {
 	__I40E_MDD_EVENT_PENDING,
 	__I40E_VFLR_EVENT_PENDING,
 	__I40E_RESET_RECOVERY_PENDING,
+	__I40E_TIMEOUT_RECOVERY_PENDING,
 	__I40E_MISC_IRQ_REQUESTED,
 	__I40E_RESET_INTR_RECEIVED,
 	__I40E_REINIT_REQUESTED,
diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c b/drivers/net/ethernet/intel/i40e/i40e_main.c
index 0e5dc74b4ef2..419cf3faada6 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_main.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
@@ -338,6 +338,10 @@ static void i40e_tx_timeout(struct net_device *netdev)
 		      (pf->tx_timeout_last_recovery + netdev->watchdog_timeo)))
 		return;   /* don't do any new action before the next timeout */
 
+	/* don't kick off another recovery if one is already pending */
+	if (test_and_set_bit(__I40E_TIMEOUT_RECOVERY_PENDING, pf->state))
+		return;
+
 	if (tx_ring) {
 		head = i40e_get_head(tx_ring);
 		/* Read interrupt register */
@@ -9632,6 +9636,7 @@ end_core_reset:
 	clear_bit(__I40E_RESET_FAILED, pf->state);
 clear_recovery:
 	clear_bit(__I40E_RESET_RECOVERY_PENDING, pf->state);
+	clear_bit(__I40E_TIMEOUT_RECOVERY_PENDING, pf->state);
 }
 
 /**
-- 
2.19.1