linux-kernel - Re: [PATCH v4 2/7] Input: use input_device

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Message-ID: <9c784a23-eade-eacd-3e67-d344a5758b83@collabora.com>
Date:   Mon, 7 Dec 2020 16:50:03 +0100
From:   Andrzej Pietrasiewicz <andrzej.p@...labora.com>
To:     Marek Szyprowski <m.szyprowski@...sung.com>,
        linux-pm@...r.kernel.org, linux-acpi@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-input@...r.kernel.org,
        linux-tegra@...r.kernel.org, patches@...nsource.cirrus.com,
        ibm-acpi-devel@...ts.sourceforge.net,
        platform-driver-x86@...r.kernel.org
Cc:     "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>,
        Jonathan Cameron <jic23@...nel.org>,
        Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Kukjin Kim <kgene@...nel.org>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>,
        Vladimir Zapolskiy <vz@...ia.com>,
        Sylvain Lemieux <slemieux.tyco@...il.com>,
        Laxman Dewangan <ldewangan@...dia.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Barry Song <baohua@...nel.org>,
        Michael Hennerich <michael.hennerich@...log.com>,
        Nick Dyer <nick@...anahar.org>,
        Hans de Goede <hdegoede@...hat.com>,
        Ferruh Yigit <fery@...ress.com>,
        Sangwon Jee <jeesw@...fas.com>,
        Peter Hutterer <peter.hutterer@...hat.com>,
        Henrique de Moraes Holschuh <ibm-acpi@....eng.br>,
        kernel@...labora.com,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
Subject: Re: [PATCH v4 2/7] Input: use input_device_enabled()

Hi Marek,

W dniu 07.12.2020 o 14:32, Marek Szyprowski pisze:
> Hi Andrzej,
> 
> On 08.06.2020 13:22, Andrzej Pietrasiewicz wrote:
>> Use the newly added helper in relevant input drivers.
>>
>> Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@...labora.com>
> 
> This patch landed recently in linux-next as commit d69f0a43c677 ("Input:
> use input_device_enabled()"). Sadly it causes following warning during
> system suspend/resume cycle on ARM 32bit Samsung Exynos5250-based Snow
> Chromebook with kernel compiled from exynos_defconfig:
> 
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 1777 at drivers/input/input.c:2230
> input_device_enabled+0x68/0x6c
> Modules linked in: cmac bnep mwifiex_sdio mwifiex sha256_generic
> libsha256 sha256_arm cfg80211 btmrvl_sdio btmrvl bluetooth s5p_mfc
> exynos_gsc v4l2_mem2mem videob
> CPU: 0 PID: 1777 Comm: rtcwake Not tainted
> 5.10.0-rc6-next-20201207-00001-g49a0dc04c46d-dirty #9902
> Hardware name: Samsung Exynos (Flattened Device Tree)
> [<c0111718>] (unwind_backtrace) from [<c010d050>] (show_stack+0x10/0x14)
> [<c010d050>] (show_stack) from [<c0b32810>] (dump_stack+0xb4/0xd4)
> [<c0b32810>] (dump_stack) from [<c0126e24>] (__warn+0xd8/0x11c)
> [<c0126e24>] (__warn) from [<c0126f18>] (warn_slowpath_fmt+0xb0/0xb8)
> [<c0126f18>] (warn_slowpath_fmt) from [<c07fa2fc>]
> (input_device_enabled+0x68/0x6c)
> [<c07fa2fc>] (input_device_enabled) from [<c080a0f8>]

Apparently you are hitting this line of code in drivers/input/input.c:

lockdep_assert_held(&dev->mutex);

Inspecting input device's "users" member should happen under dev's lock.

Regards,

Andrzej