From: Jakub Kicinski <kuba@kernel.org>
To: dipayanroy@linux.microsoft.com
Cc: Jakub Kicinski <kuba@kernel.org>,
kys@microsoft.com, haiyangz@microsoft.com, wei.liu@kernel.org,
decui@microsoft.com, andrew+netdev@lunn.ch, davem@davemloft.net,
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longli@microsoft.com, kotaranov@microsoft.com, horms@kernel.org,
shradhagupta@linux.microsoft.com, ssengar@linux.microsoft.com,
ernis@linux.microsoft.com, shirazsaleem@microsoft.com,
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linux-kernel@vger.kernel.org, linux-rdma@vger.kernel.org,
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john.fastabend@gmail.com, hawk@kernel.org, bpf@vger.kernel.org,
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yury.norov@gmail.com
Subject: Re: [PATCH net 2/2] net: mana: Skip redundant detach in queue reset handler if already detached
Date: Tue, 19 May 2026 15:55:59 -0700 [thread overview]
Message-ID: <20260519225559.3939235-1-kuba@kernel.org> (raw)
In-Reply-To: <20260518194654.735580-3-dipayanroy@linux.microsoft.com>
This is an AI-generated review of your patch. The human sending this
email has considered the AI review valid, or at least plausible.
---
net: mana: Skip redundant detach in queue reset handler if already detached
This commit adds a check for netif_device_present() in the queue reset
handler. If the device is already detached, it skips the redundant
mana_detach() call and proceeds directly to mana_attach().
> diff --git a/drivers/net/ethernet/microsoft/mana/mana_en.c b/drivers/net/ethernet/microsoft/mana/mana_en.c
> index 9e7e4bf526bf6..740f3c34db451 100644
> --- a/drivers/net/ethernet/microsoft/mana/mana_en.c
> +++ b/drivers/net/ethernet/microsoft/mana/mana_en.c
> @@ -316,12 +316,19 @@ static void mana_per_port_queue_reset_work_handler(struct work_struct *work)
[ ... ]
> + /* If already detached (indicates detach succeeded but attach failed
> + * previously). Now skip mana detach and just retry mana_attach.
> + */
> + if (!netif_device_present(ndev))
> + goto attach;
> +
> err = mana_detach(ndev, false);
The fix here correctly prevents mana_detach() from running on an already
detached device. However, do identical issues remain in mana_change_mtu(),
mana_set_channels(), mana_set_ringparam(), and mana_bpf()?
If mana_attach() previously failed (for example, due to out of memory),
the port is left with apc->port_is_up = false, but it preserves
apc->port_st_save = true, and calls netif_device_detach(ndev).
If an admin tries to recover the port by retrying a configuration command
like changing the MTU or attaching XDP, these functions appear to
unconditionally call mana_detach(ndev, false) without the
!netif_device_present(ndev) check added here.
Inside mana_detach(), apc->port_st_save = apc->port_is_up executes. Since
port_is_up is already false, port_st_save is overwritten to false,
permanently erasing the intent that the port should be up.
The subsequent call to mana_attach() would then see port_st_save == false,
skip mana_alloc_queues(), set port_is_up = false, and successfully call
netif_device_attach(ndev).
Would this result in the configuration command returning 0 to userspace
while the port queues were never allocated, leaving the interface silently
broken until manually toggled down and up?
next prev parent reply other threads:[~2026-05-19 22:56 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-18 19:43 [PATCH net 0/2] net: mana: Fix NULL dereferences during teardown after attach failure Dipayaan Roy
2026-05-18 19:43 ` [PATCH net 1/2] net: mana: Add NULL guards in teardown path to prevent panic on " Dipayaan Roy
2026-05-18 21:49 ` Harshitha Ramamurthy
2026-05-19 22:55 ` Jakub Kicinski
2026-05-20 18:11 ` Dipayaan Roy
2026-05-18 19:43 ` [PATCH net 2/2] net: mana: Skip redundant detach in queue reset handler if already detached Dipayaan Roy
2026-05-19 22:55 ` Jakub Kicinski [this message]
2026-05-20 18:23 ` Dipayaan Roy
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