netdev - RE: [PATCH net, 1/2] net: mana: Fix hint value before free irq

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Date:   Sun, 29 Jan 2023 14:26:24 +0000
From:   "Michael Kelley (LINUX)" <mikelley@...rosoft.com>
To:     Haiyang Zhang <haiyangz@...rosoft.com>,
        "linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
CC:     Haiyang Zhang <haiyangz@...rosoft.com>,
        Dexuan Cui <decui@...rosoft.com>,
        KY Srinivasan <kys@...rosoft.com>,
        Paul Rosswurm <paulros@...rosoft.com>,
        "olaf@...fle.de" <olaf@...fle.de>,
        "vkuznets@...hat.com" <vkuznets@...hat.com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
Subject: RE: [PATCH net, 1/2] net: mana: Fix hint value before free irq

From: LKML haiyangz <lkmlhyz@...rosoft.com> On Behalf Of Haiyang Zhang Sent: Thursday, January 26, 2023 1:05 PM
> 
> Need to clear affinity_hint before free_irq(), otherwise there is a
> one-time warning and stack trace during module unloading.
> 
> To fix this bug, set affinity_hint to NULL before free as required.
> 
> Cc: stable@...r.kernel.org
> Fixes: 71fa6887eeca ("net: mana: Assign interrupts to CPUs based on NUMA nodes")
> Signed-off-by: Haiyang Zhang <haiyangz@...rosoft.com>
> ---
>  drivers/net/ethernet/microsoft/mana/gdma_main.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/net/ethernet/microsoft/mana/gdma_main.c
> b/drivers/net/ethernet/microsoft/mana/gdma_main.c
> index b144f2237748..3bae9d4c1f08 100644
> --- a/drivers/net/ethernet/microsoft/mana/gdma_main.c
> +++ b/drivers/net/ethernet/microsoft/mana/gdma_main.c
> @@ -1297,6 +1297,8 @@ static int mana_gd_setup_irqs(struct pci_dev *pdev)
>  	for (j = i - 1; j >= 0; j--) {
>  		irq = pci_irq_vector(pdev, j);
>  		gic = &gc->irq_contexts[j];
> +
> +		irq_update_affinity_hint(irq, NULL);
>  		free_irq(irq, gic);
>  	}
> 
> @@ -1324,6 +1326,9 @@ static void mana_gd_remove_irqs(struct pci_dev *pdev)
>  			continue;
> 
>  		gic = &gc->irq_contexts[i];
> +
> +		/* Need to clear the hint before free_irq */
> +		irq_update_affinity_hint(irq, NULL);
>  		free_irq(irq, gic);
>  	}
> 
> --
> 2.25.1

I think this patch should be folded into the second patch of this series.  While
this patch makes the warning go away, it doesn't really solve any problems by
itself.  It just papers over the warning.  My first reaction on seeing this patch
is that the warning exists because the memory for the mask likely had
been incorrectly managed, which is exactly the case.  Since this patch doesn't
really fix a problem on its own, I'd say merge it into the second patch.

That's just my $.02.  If you really want to keep it separate, that's not a
blocker for me.

Michael