netdev - Re: [PATCH net 1/3] igb: Disable threaded IRQ for igb_msix

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20241024084732.GE402847@kernel.org>
Date: Thu, 24 Oct 2024 09:47:32 +0100
From: Simon Horman <horms@...nel.org>
To: Jacob Keller <jacob.e.keller@...el.com>
Cc: Przemek Kitszel <przemyslaw.kitszel@...el.com>,
	Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Jeff Garzik <jgarzik@...hat.com>,
	Michal Swiatkowski <michal.swiatkowski@...ux.intel.com>,
	Piotr Raczynski <piotr.raczynski@...el.com>,
	Vadim Fedorenko <vadim.fedorenko@...ux.dev>,
	Milena Olech <milena.olech@...el.com>,
	Arkadiusz Kubalewski <arkadiusz.kubalewski@...el.com>,
	Michal Michalik <michal.michalik@...el.com>,
	netdev <netdev@...r.kernel.org>, Jiri Pirko <jiri@...nulli.us>,
	Wander Lairson Costa <wander@...hat.com>,
	Yuying Ma <yuma@...hat.com>,
	Rafal Romanowski <rafal.romanowski@...el.com>
Subject: Re: [PATCH net 1/3] igb: Disable threaded IRQ for igb_msix_other

On Mon, Oct 21, 2024 at 04:26:24PM -0700, Jacob Keller wrote:
> From: Wander Lairson Costa <wander@...hat.com>
> 
> During testing of SR-IOV, Red Hat QE encountered an issue where the
> ip link up command intermittently fails for the igbvf interfaces when
> using the PREEMPT_RT variant. Investigation revealed that
> e1000_write_posted_mbx returns an error due to the lack of an ACK
> from e1000_poll_for_ack.
> 
> The underlying issue arises from the fact that IRQs are threaded by
> default under PREEMPT_RT. While the exact hardware details are not
> available, it appears that the IRQ handled by igb_msix_other must
> be processed before e1000_poll_for_ack times out. However,
> e1000_write_posted_mbx is called with preemption disabled, leading
> to a scenario where the IRQ is serviced only after the failure of
> e1000_write_posted_mbx.
> 
> To resolve this, we set IRQF_NO_THREAD for the affected interrupt,
> ensuring that the kernel handles it immediately, thereby preventing
> the aforementioned error.
> 
> Reproducer:
> 
>     #!/bin/bash
> 
>     # echo 2 > /sys/class/net/ens14f0/device/sriov_numvfs
>     ipaddr_vlan=3
>     nic_test=ens14f0
>     vf=${nic_test}v0
> 
>     while true; do
> 	    ip link set ${nic_test} mtu 1500
> 	    ip link set ${vf} mtu 1500
> 	    ip link set $vf up
> 	    ip link set ${nic_test} vf 0 vlan ${ipaddr_vlan}
> 	    ip addr add 172.30.${ipaddr_vlan}.1/24 dev ${vf}
> 	    ip addr add 2021:db8:${ipaddr_vlan}::1/64 dev ${vf}
> 	    if ! ip link show $vf | grep 'state UP'; then
> 		    echo 'Error found'
> 		    break
> 	    fi
> 	    ip link set $vf down
>     done
> 
> Signed-off-by: Wander Lairson Costa <wander@...hat.com>
> Fixes: 9d5c824399de ("igb: PCI-Express 82575 Gigabit Ethernet driver")
> Reported-by: Yuying Ma <yuma@...hat.com>
> Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@...el.com>
> Tested-by: Rafal Romanowski <rafal.romanowski@...el.com>
> Signed-off-by: Jacob Keller <jacob.e.keller@...el.com>

Reviewed-by: Simon Horman <horms@...nel.org>