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From: Stephen Hemminger <stephen@networkplumber.org>
To: Luc Pelletier <lucp.at.work@gmail.com>
Cc: grive@u256.net, dev@dpdk.org, konstantin.ananyev@huawei.com,
	stable@dpdk.org
Subject: Re: [PATCH v3 1/5] failsafe: fix segfault on hotplug event
Date: Tue, 31 Oct 2023 10:35:28 -0700	[thread overview]
Message-ID: <20231031103528.5fa26855@fedora> (raw)
In-Reply-To: <20221129144832.2750-2-lucp.at.work@gmail.com>

On Tue, 29 Nov 2022 09:48:29 -0500
Luc Pelletier <lucp.at.work@gmail.com> wrote:

> When the failsafe PMD encounters a hotplug event, it switches its rx/tx
> functions to "safe" ones that validate the sub-device's rx/tx functions
> before calling them. It switches the rx/tx functions by changing the
> function pointers in the rte_eth_dev structure.
> 
> Following commit 7a0935239b9e, the rx/tx functions of PMDs are no longer
> called through the function pointers in the rte_eth_dev structure. They
> are rather called through a flat array named rte_eth_fp_ops. The
> function pointers in that array are initialized when the devices start
> and are initialized.
> 
> When a hotplug event occurs, the function pointers in rte_eth_fp_ops
> still point to the "unsafe" rx/tx functions in the failsafe PMD since
> they haven't been updated. This results in a segmentation fault because
> it ends up using the "unsafe" functions, when the "safe" functions
> should have been used.
> 
> To fix the problem, the "unsafe" rx/tx functions were completely
> removed. The "safe" functions are now always used. Modifying the rx/tx
> functions on-the-fly is not supported by DPDK, so this is the correct
> approach and should have very minimal impact on performance.
> 
> Fixes: 7a0935239b9e ("ethdev: make fast-path functions to use new flat array")
> Cc: Konstantin Ananyev <konstantin.ananyev@huawei.com>
> Cc: stable@dpdk.org
> 
> Signed-off-by: Luc Pelletier <lucp.at.work@gmail.com>


I don't use or have way to test failsafe anymore.
But wanted to give a try at reviewing this.
This version does not apply to current code base.
If still interested, please rebase and resubmit.

  reply	other threads:[~2023-10-31 17:35 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-11-10 16:34 [PATCH] " Luc Pelletier
2022-11-10 17:42 ` [PATCH v2] " Luc Pelletier
2022-11-10 23:33   ` Stephen Hemminger
2022-11-16 17:35 ` [PATCH] " Konstantin Ananyev
2022-11-16 21:51   ` Luc Pelletier
2022-11-16 22:25     ` Stephen Hemminger
2022-11-18 16:31       ` Konstantin Ananyev
2022-11-29 14:48 ` [PATCH v3 0/5] Failsafe bug fixes and improvements Luc Pelletier
2022-11-29 14:48 ` [PATCH v3 1/5] failsafe: fix segfault on hotplug event Luc Pelletier
2023-10-31 17:35   ` Stephen Hemminger [this message]
2022-11-29 14:48 ` [PATCH v3 2/5] failsafe: use public rx/tx burst API Luc Pelletier
2022-11-29 14:48 ` [PATCH v3 3/5] failsafe: fix double release of port Luc Pelletier
2022-11-29 14:48 ` [PATCH v3 4/5] failsafe: use public APIs in fs_link_update Luc Pelletier
2022-11-29 14:48 ` [PATCH v3 5/5] failsafe: make sub-device remove flag thread-safe Luc Pelletier
2022-11-29 15:25 ` [PATCH v4 0/5] Failsafe bug fixes and improvements Luc Pelletier
2022-11-29 15:25 ` [PATCH v4 1/5] failsafe: fix segfault on hotplug event Luc Pelletier
2022-11-29 15:25 ` [PATCH v4 2/5] failsafe: use public rx/tx burst API Luc Pelletier
2022-11-29 15:25 ` [PATCH v4 3/5] failsafe: fix double release of port Luc Pelletier
2022-11-29 15:25 ` [PATCH v4 4/5] failsafe: use public APIs in fs_link_update Luc Pelletier
2022-11-29 15:25 ` [PATCH v4 5/5] failsafe: make sub-device remove flag thread-safe Luc Pelletier

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