Re: [PATCH v2] net: stmmac: fix incorrect rxq|txq_stats reference - Uwe Kleine-König

From: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
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
Subject: Re: [PATCH v2] net: stmmac: fix incorrect rxq|txq_stats reference
Date: Sun, 17 Sep 2023 22:19:46 +0200	[thread overview]
Message-ID: <20230917201946.5z5y2qn4ydpwppse@pengutronix.de> (raw)
In-Reply-To: <20230917165328.3403-1-jszhang@kernel.org>

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On Mon, Sep 18, 2023 at 12:53:28AM +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>

I didn't look at the patch, but it makes the splat go away for me.
Thanks \o/

Tested-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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