Re: [PATCH] net: stmmac: fix incorrect rxq|txq_stats reference

From: Simon Horman <horms@kernel.org>
To: Jisheng Zhang <jszhang@kernel.org>
Cc: "Giuseppe Cavallaro" <peppe.cavallaro@st.com>,
	"Alexandre Torgue" <alexandre.torgue@foss.st.com>,
	"Jose Abreu" <joabreu@synopsys.com>,
	"David S . Miller" <davem@davemloft.net>,
	"Eric Dumazet" <edumazet@google.com>,
	"Jakub Kicinski" <kuba@kernel.org>,
	"Paolo Abeni" <pabeni@redhat.com>,
	"Maxime Coquelin" <mcoquelin.stm32@gmail.com>,
	"Chen-Yu Tsai" <wens@csie.org>,
	"Jernej Skrabec" <jernej.skrabec@gmail.com>,
	"Samuel Holland" <samuel@sholland.org>,
	netdev@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-sunxi@lists.linux.dev,
	linux-stm32@st-md-mailman.stormreply.com,
	johannes@sipsolutions.net,
	"Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
Subject: Re: [PATCH] net: stmmac: fix incorrect rxq|txq_stats reference
Date: Sat, 16 Sep 2023 17:47:37 +0200	[thread overview]
Message-ID: <20230916154737.GG1125562@kernel.org> (raw)
In-Reply-To: <20230915005316.592-1-jszhang@kernel.org>

On Fri, Sep 15, 2023 at 08:53:16AM +0800, Jisheng Zhang wrote:
> commit 133466c3bbe1 ("net: stmmac: use per-queue 64 bit statistics
> where necessary") caused one regression as found by Uwe, the backtrace
> looks like:
> 
> INFO: trying to register non-static key.
> The code is fine but needs lockdep annotation, or maybe
> you didn't initialize this object before use?
> turning off the locking correctness validator.
> CPU: 0 PID: 1 Comm: swapper/0 Not tainted 6.5.0-rc1-00449-g133466c3bbe1-dirty #21
> Hardware name: STM32 (Device Tree Support)
>  unwind_backtrace from show_stack+0x18/0x1c
>  show_stack from dump_stack_lvl+0x60/0x90
>  dump_stack_lvl from register_lock_class+0x98c/0x99c
>  register_lock_class from __lock_acquire+0x74/0x293c
>  __lock_acquire from lock_acquire+0x134/0x398
>  lock_acquire from stmmac_get_stats64+0x2ac/0x2fc
>  stmmac_get_stats64 from dev_get_stats+0x44/0x130
>  dev_get_stats from rtnl_fill_stats+0x38/0x120
>  rtnl_fill_stats from rtnl_fill_ifinfo+0x834/0x17f4
>  rtnl_fill_ifinfo from rtmsg_ifinfo_build_skb+0xc0/0x144
>  rtmsg_ifinfo_build_skb from rtmsg_ifinfo+0x50/0x88
>  rtmsg_ifinfo from __dev_notify_flags+0xc0/0xec
>  __dev_notify_flags from dev_change_flags+0x50/0x5c
>  dev_change_flags from ip_auto_config+0x2f4/0x1260
>  ip_auto_config from do_one_initcall+0x70/0x35c
>  do_one_initcall from kernel_init_freeable+0x2ac/0x308
>  kernel_init_freeable from kernel_init+0x1c/0x138
>  kernel_init from ret_from_fork+0x14/0x2c
> 
> The reason is the rxq|txq_stats structures are not what expected
> because stmmac_open() -> __stmmac_open() the structure is overwritten
> by "memcpy(&priv->dma_conf, dma_conf, sizeof(*dma_conf));"
> This causes the well initialized syncp member of rxq|txq_stats is
> overwritten unexpectedly as pointed out by Johannes and Uwe.
> 
> Fix this issue by moving rxq|txq_stats back to stmmac_extra_stats. For
> SMP cache friendly, we also mark stmmac_txq_stats and stmmac_rxq_stats
> as ____cacheline_aligned_in_smp.
> 
> Fixes: 133466c3bbe1 ("net: stmmac: use per-queue 64 bit statistics where necessary")
> Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
> Reported-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

Hi Jisheng Zhang,

as a fix for Networking code this should be based targeted at the net tree.

  Subject: [PATCH net] ...

Unfortunately it doesn't apply cleanly against net.
Please consider rebasing and reposting.

-- 
pw-bot: changes-requested