linux-kernel - [PATCH 1/2 V3 net] net: mana: Fix MANA VF unload when host is unresponsive

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Message-Id: <1687771098-26775-1-git-send-email-schakrabarti@linux.microsoft.com>
Date:   Mon, 26 Jun 2023 02:18:18 -0700
From:   souradeep chakrabarti <schakrabarti@...ux.microsoft.com>
To:     kys@...rosoft.com, haiyangz@...rosoft.com, wei.liu@...nel.org,
        decui@...rosoft.com, davem@...emloft.net, edumazet@...gle.com,
        kuba@...nel.org, pabeni@...hat.com, longli@...rosoft.com,
        sharmaajay@...rosoft.com, leon@...nel.org, cai.huoqing@...ux.dev,
        ssengar@...ux.microsoft.com, vkuznets@...hat.com,
        tglx@...utronix.de, linux-hyperv@...r.kernel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-rdma@...r.kernel.org
Cc:     stable@...r.kernel.org, schakrabarti@...rosoft.com,
        Souradeep Chakrabarti <schakrabarti@...ux.microsoft.com>
Subject: [PATCH 1/2 V3 net] net: mana: Fix MANA VF unload when host is unresponsive

From: Souradeep Chakrabarti <schakrabarti@...ux.microsoft.com>

This patch addresses the VF unload issue, where mana_dealloc_queues()
gets stuck in infinite while loop, because of host unresponsiveness.
It adds a timeout in the while loop, to fix it.

Fixes: ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f (net: mana: Add a driver for
Microsoft Azure Network Adapter)
Signed-off-by: Souradeep Chakrabarti <schakrabarti@...ux.microsoft.com>
---
V2 -> V3:
* Splitted the patch in two parts.
* Removed the unnecessary braces from mana_dealloc_queues().
---
 drivers/net/ethernet/microsoft/mana/mana_en.c | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/microsoft/mana/mana_en.c b/drivers/net/ethernet/microsoft/mana/mana_en.c
index d907727c7b7a..cb5c43c3c47e 100644
--- a/drivers/net/ethernet/microsoft/mana/mana_en.c
+++ b/drivers/net/ethernet/microsoft/mana/mana_en.c
@@ -2329,7 +2329,10 @@ static int mana_dealloc_queues(struct net_device *ndev)
 {
 	struct mana_port_context *apc = netdev_priv(ndev);
 	struct gdma_dev *gd = apc->ac->gdma_dev;
+	unsigned long timeout;
 	struct mana_txq *txq;
+	struct sk_buff *skb;
+	struct mana_cq *cq;
 	int i, err;
 
 	if (apc->port_is_up)
@@ -2348,13 +2351,25 @@ static int mana_dealloc_queues(struct net_device *ndev)
 	 *
 	 * Drain all the in-flight TX packets
 	 */
+
+	timeout = jiffies + 120 * HZ;
 	for (i = 0; i < apc->num_queues; i++) {
 		txq = &apc->tx_qp[i].txq;
-
-		while (atomic_read(&txq->pending_sends) > 0)
+		while (atomic_read(&txq->pending_sends) > 0 &&
+		       time_before(jiffies, timeout))
 			usleep_range(1000, 2000);
 	}
 
+	for (i = 0; i < apc->num_queues; i++) {
+		txq = &apc->tx_qp[i].txq;
+		cq = &apc->tx_qp[i].tx_cq;
+		while (atomic_read(&txq->pending_sends)) {
+			skb = skb_dequeue(&txq->pending_skbs);
+			mana_unmap_skb(skb, apc);
+			napi_consume_skb(skb, cq->budget);
+			atomic_sub(1, &txq->pending_sends);
+		}
+	}
 	/* We're 100% sure the queues can no longer be woken up, because
 	 * we're sure now mana_poll_tx_cq() can't be running.
 	 */
-- 
2.34.1