linux-kernel - [PATCH 4.19 037/313] i40e: prevent overlapping tx

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Date:   Mon, 11 Feb 2019 15:15:17 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Alan Brady <alan.brady@...el.com>,
        Andrew Bowers <andrewx.bowers@...el.com>,
        Jeff Kirsher <jeffrey.t.kirsher@...el.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.19 037/313] i40e: prevent overlapping tx_timeout recover

4.19-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@...el.com>
Tested-by: Andrew Bowers <andrewx.bowers@...el.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@...el.com>
Signed-off-by: Sasha Levin <sashal@...nel.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 7a80652e2500..f84e2c2d02c0 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 ed9d3fc4aaba..bfa5c525cf31 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_main.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
@@ -336,6 +336,10 @@ 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 */
@@ -9566,6 +9570,7 @@ 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