RE: [PATCH V4 net] net: mana: Fix MANA VF unload when host is unresponsive

Haiyang Zhang
2023-07-03T15:51:35Z

> -----Original Message-----
> From: souradeep chakrabarti <schakrabarti@linux.microsoft.com>
> Sent: Monday, July 3, 2023 4:50 AM
> To: KY Srinivasan <kys@microsoft.com>; Haiyang Zhang
> <haiyangz@microsoft.com>; wei.liu@kernel.org; Dexuan Cui
> <decui@microsoft.com>; davem@davemloft.net; edumazet@google.com;
> kuba@kernel.org; pabeni@redhat.com; Long Li <longli@microsoft.com>; Ajay
> Sharma <sharmaajay@microsoft.com>; leon@kernel.org;
> cai.huoqing@linux.dev; ssengar@linux.microsoft.com; vkuznets@redhat.com;
> tglx@linutronix.de; linux-hyperv@vger.kernel.org; netdev@vger.kernel.org;
> linux-kernel@vger.kernel.org; linux-rdma@vger.kernel.org
> Cc: stable@vger.kernel.org; Souradeep Chakrabarti
> <schakrabarti@microsoft.com>; Souradeep Chakrabarti
> <schakrabarti@linux.microsoft.com>
> Subject: [PATCH V4 net] net: mana: Fix MANA VF unload when host is
> unresponsive
>
> From: Souradeep Chakrabarti <schakrabarti@linux.microsoft.com>
>
> When unloading the MANA driver, mana_dealloc_queues() waits for the MANA
> hardware to complete any inflight packets and set the pending send count
> to zero. But if the hardware has failed, mana_dealloc_queues()
> could wait forever.
>
> Fix this by adding a timeout to the wait. Set the timeout to 120 seconds,
> which is a somewhat arbitrary value that is more than long enough for
> functional hardware to complete any sends.
>
> Signed-off-by: Souradeep Chakrabarti <schakrabarti@linux.microsoft.com>
> ---
> V3 -> V4:
> * Fixed the commit message to describe the context.
> * Removed the vf_unload_timeout, as it is not required.
> ---
> drivers/net/ethernet/microsoft/mana/mana_en.c | 26 ++++++++++++++++---
> 1 file changed, 23 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/ethernet/microsoft/mana/mana_en.c
> b/drivers/net/ethernet/microsoft/mana/mana_en.c
> index a499e460594b..d26f1da70411 100644
> --- a/drivers/net/ethernet/microsoft/mana/mana_en.c
> +++ b/drivers/net/ethernet/microsoft/mana/mana_en.c
> @@ -2346,7 +2346,10 @@ 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)
> @@ -2363,15 +2366,32 @@ static int mana_dealloc_queues(struct net_device
> *ndev)
> * to false, but it doesn't matter since mana_start_xmit() drops any
> * new packets due to apc->port_is_up being false.
> *
> - * Drain all the in-flight TX packets
> + * Drain all the in-flight TX packets.
> + * A timeout of 120 seconds for all the queues is used.
> + * This will break the while loop when h/w is not responding.
> + * This value of 120 has been decided here considering max
> + * number of queues.
> */
> +
> + 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);

This is not in NAPI context, so it should be dev_consume_skb_any()

Thanks,
- Haiyang