netdev - Re: [PATCH net-next 6/7] eth: via-rhine: fix calling napi

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Message-ID: <CANn89iJ7XcNJDKqzZ6pRo4peSd9MntiSjoxMyrrhCrrvjjHObg@mail.gmail.com>
Date: Wed, 22 Jan 2025 15:20:11 +0100
From: Eric Dumazet <edumazet@...gle.com>
To: Jakub Kicinski <kuba@...nel.org>
Cc: davem@...emloft.net, netdev@...r.kernel.org, pabeni@...hat.com, 
	andrew+netdev@...n.ch, horms@...nel.org, dan.carpenter@...aro.org, 
	kevinbrace@...cecomputerlab.com, romieu@...zoreil.com, kuniyu@...zon.com
Subject: Re: [PATCH net-next 6/7] eth: via-rhine: fix calling napi_enable() in
 atomic context

On Tue, Jan 21, 2025 at 11:15 PM Jakub Kicinski <kuba@...nel.org> wrote:
>
> napi_enable() may sleep now, take netdev_lock() before rp->lock.
> napi_enable() is hidden inside init_registers().
>
> Note that this patch orders netdev_lock after rp->task_lock,
> to avoid having to take the netdev_lock() around disable path.
>
> Fixes: 413f0271f396 ("net: protect NAPI enablement with netdev_lock()")
> Reported-by: Dan Carpenter <dan.carpenter@...aro.org>
> Link: https://lore.kernel.org/dcfd56bc-de32-4b11-9e19-d8bd1543745d@stanley.mountain
> Signed-off-by: Jakub Kicinski <kuba@...nel.org>
> ---
> CC: kevinbrace@...cecomputerlab.com
> CC: romieu@...zoreil.com
> CC: kuniyu@...zon.com
> ---
>  drivers/net/ethernet/via/via-rhine.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
>

Hmm. I  think you forgot this chunk :

diff --git a/drivers/net/ethernet/via/via-rhine.c
b/drivers/net/ethernet/via/via-rhine.c
index 894911f3d5603c109cba7651b6b047b59ec85c9..4e59b5da063e1690fce0f210c33143a42745810
100644
--- a/drivers/net/ethernet/via/via-rhine.c
+++ b/drivers/net/ethernet/via/via-rhine.c
@@ -1568,7 +1568,7 @@ static void init_registers(struct net_device *dev)
        if (rp->quirks & rqMgmt)
                rhine_init_cam_filter(dev);

-       napi_enable(&rp->napi);
+       napi_enable_locked(&rp->napi);

        iowrite16(RHINE_EVENT & 0xffff, ioaddr + IntrEnable);





> diff --git a/drivers/net/ethernet/via/via-rhine.c b/drivers/net/ethernet/via/via-rhine.c
> index 894911f3d560..f27157561082 100644
> --- a/drivers/net/ethernet/via/via-rhine.c
> +++ b/drivers/net/ethernet/via/via-rhine.c
> @@ -1696,7 +1696,10 @@ static int rhine_open(struct net_device *dev)
>         rhine_power_init(dev);
>         rhine_chip_reset(dev);
>         rhine_task_enable(rp);
> +
> +       netdev_lock(dev);
>         init_registers(dev);
> +       netdev_unlock(dev);
>
>         netif_dbg(rp, ifup, dev, "%s() Done - status %04x MII status: %04x\n",
>                   __func__, ioread16(ioaddr + ChipCmd),
> @@ -1727,6 +1730,8 @@ static void rhine_reset_task(struct work_struct *work)
>
>         napi_disable(&rp->napi);
>         netif_tx_disable(dev);
> +
> +       netdev_lock(dev);
>         spin_lock_bh(&rp->lock);
>
>         /* clear all descriptors */
> @@ -1740,6 +1745,7 @@ static void rhine_reset_task(struct work_struct *work)
>         init_registers(dev);
>
>         spin_unlock_bh(&rp->lock);
> +       netdev_unlock(dev);
>
>         netif_trans_update(dev); /* prevent tx timeout */
>         dev->stats.tx_errors++;
> @@ -2541,9 +2547,12 @@ static int rhine_resume(struct device *device)
>         alloc_tbufs(dev);
>         rhine_reset_rbufs(rp);
>         rhine_task_enable(rp);
> +
> +       netdev_lock(dev);
>         spin_lock_bh(&rp->lock);
>         init_registers(dev);
>         spin_unlock_bh(&rp->lock);
> +       netdev_unlock(dev);
>
>         netif_device_attach(dev);
>
> --
> 2.48.1
>