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Subject: Re: [PATCH v2] media: i2c: max9286: fix kernel oops when removing module
From:   Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Cc:     Laurentiu Palcu <laurentiu.palcu@oss.nxp.com>,
        Mauro Carvalho Chehab <mchehab+huawei@kernel.org>,
        Sakari Ailus <sakari.ailus@linux.intel.com>,
        linux-media@vger.kernel.org, linux-kernel@vger.kernel.org
To:     Jacopo Mondi <jacopo+renesas@jmondi.org>,
        Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>,
        Laurentiu Palcu <laurentiu.palcu@oss.nxp.com>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Niklas =?utf-8?q?S=C3=B6derlund?= 
        <niklas.soderlund+renesas@ragnatech.se>
Date:   Tue, 22 Mar 2022 21:59:08 +0000
Message-ID: <164798634811.506124.11264777382844163635@Monstersaurus>
User-Agent: alot/0.10
Precedence: bulk

Hi Laurentiu,

Thanks for the updates on the v2, Looks good to me.

Quoting Laurentiu Palcu (2022-03-07 16:46:07)
> When removing the max9286 module we get a kernel oops:
>=20
> Unable to handle kernel paging request at virtual address 000000aa00000094
> Mem abort info:
>   ESR =3D 0x96000004
>   EC =3D 0x25: DABT (current EL), IL =3D 32 bits
>   SET =3D 0, FnV =3D 0
>   EA =3D 0, S1PTW =3D 0
>   FSC =3D 0x04: level 0 translation fault
> Data abort info:
>   ISV =3D 0, ISS =3D 0x00000004
>   CM =3D 0, WnR =3D 0
> user pgtable: 4k pages, 48-bit VAs, pgdp=3D0000000880d85000
> [000000aa00000094] pgd=3D0000000000000000, p4d=3D0000000000000000
> Internal error: Oops: 96000004 [#1] PREEMPT SMP
> Modules linked in: fsl_jr_uio caam_jr rng_core libdes caamkeyblob_desc ca=
amhash_desc caamalg_desc crypto_engine max9271 authenc crct10dif_ce mxc_jpe=
g_encdec
> CPU: 2 PID: 713 Comm: rmmod Tainted: G         C        5.15.5-00057-gaeb=
cd29c8ed7-dirty #5
> Hardware name: Freescale i.MX8QXP MEK (DT)
> pstate: 80000005 (Nzcv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=3D--)
> pc : i2c_mux_del_adapters+0x24/0xf0
> lr : max9286_remove+0x28/0xd0 [max9286]
> sp : ffff800013a9bbf0
> x29: ffff800013a9bbf0 x28: ffff00080b6da940 x27: 0000000000000000
> x26: 0000000000000000 x25: 0000000000000000 x24: 0000000000000000
> x23: ffff000801a5b970 x22: ffff0008048b0890 x21: ffff800009297000
> x20: ffff0008048b0f70 x19: 000000aa00000064 x18: 0000000000000000
> x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000
> x14: 0000000000000014 x13: 0000000000000000 x12: ffff000802da49e8
> x11: ffff000802051918 x10: ffff000802da4920 x9 : ffff000800030098
> x8 : 0101010101010101 x7 : 7f7f7f7f7f7f7f7f x6 : fefefeff6364626d
> x5 : 8080808000000000 x4 : 0000000000000000 x3 : 0000000000000000
> x2 : ffffffffffffffff x1 : ffff00080b6da940 x0 : 0000000000000000
> Call trace:
>  i2c_mux_del_adapters+0x24/0xf0
>  max9286_remove+0x28/0xd0 [max9286]
>  i2c_device_remove+0x40/0x110
>  __device_release_driver+0x188/0x234
>  driver_detach+0xc4/0x150
>  bus_remove_driver+0x60/0xe0
>  driver_unregister+0x34/0x64
>  i2c_del_driver+0x58/0xa0
>  max9286_i2c_driver_exit+0x1c/0x490 [max9286]
>  __arm64_sys_delete_module+0x194/0x260
>  invoke_syscall+0x48/0x114
>  el0_svc_common.constprop.0+0xd4/0xfc
>  do_el0_svc+0x2c/0x94
>  el0_svc+0x28/0x80
>  el0t_64_sync_handler+0xa8/0x130
>  el0t_64_sync+0x1a0/0x1a4
>=20
> The Oops happens because the I2C client data does not point to
> max9286_priv anymore but to v4l2_subdev. The change happened in
> max9286_init() which calls v4l2_i2c_subdev_init() later on...
>=20
> Besides fixing the max9286_remove() function, remove the call to
> i2c_set_clientdata() in max9286_probe(), to avoid confusion, and make
> the necessary changes to max9286_init() so that it doesn't have to use
> i2c_get_clientdata() in order to fetch the pointer to priv.
>=20
> Fixes: 66d8c9d2422d ("media: i2c: Add MAX9286 driver")
> Signed-off-by: Laurentiu Palcu <laurentiu.palcu@oss.nxp.com>

Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>

> ---
> Changes in v2:
>  * removed i2c_set_clientdata() in max9286_probe();
>  * refactored max9286_init() so that we pass priv as argument, not dev;
>=20
> Cheers,
> Laurentiu
>=20
>  drivers/media/i2c/max9286.c | 19 +++++++------------
>  1 file changed, 7 insertions(+), 12 deletions(-)
>=20
> diff --git a/drivers/media/i2c/max9286.c b/drivers/media/i2c/max9286.c
> index d2a4915ed9f7..3684faa72253 100644
> --- a/drivers/media/i2c/max9286.c
> +++ b/drivers/media/i2c/max9286.c
> @@ -1147,22 +1147,18 @@ static int max9286_poc_enable(struct max9286_priv=
 *priv, bool enable)
>         return ret;
>  }
> =20
> -static int max9286_init(struct device *dev)
> +static int max9286_init(struct max9286_priv *priv)
>  {
> -       struct max9286_priv *priv;
> -       struct i2c_client *client;
> +       struct i2c_client *client =3D priv->client;
>         int ret;
> =20
> -       client =3D to_i2c_client(dev);
> -       priv =3D i2c_get_clientdata(client);
> -
>         ret =3D max9286_poc_enable(priv, true);
>         if (ret)
>                 return ret;
> =20
>         ret =3D max9286_setup(priv);
>         if (ret) {
> -               dev_err(dev, "Unable to setup max9286\n");
> +               dev_err(&client->dev, "Unable to setup max9286\n");
>                 goto err_poc_disable;
>         }
> =20
> @@ -1172,13 +1168,13 @@ static int max9286_init(struct device *dev)
>          */
>         ret =3D max9286_v4l2_register(priv);
>         if (ret) {
> -               dev_err(dev, "Failed to register with V4L2\n");
> +               dev_err(&client->dev, "Failed to register with V4L2\n");
>                 goto err_poc_disable;
>         }
> =20
>         ret =3D max9286_i2c_mux_init(priv);
>         if (ret) {
> -               dev_err(dev, "Unable to initialize I2C multiplexer\n");
> +               dev_err(&client->dev, "Unable to initialize I2C multiplex=
er\n");
>                 goto err_v4l2_register;
>         }
> =20
> @@ -1333,7 +1329,6 @@ static int max9286_probe(struct i2c_client *client)
>         mutex_init(&priv->mutex);
> =20
>         priv->client =3D client;
> -       i2c_set_clientdata(client, priv);
> =20
>         priv->gpiod_pwdn =3D devm_gpiod_get_optional(&client->dev, "enabl=
e",
>                                                    GPIOD_OUT_HIGH);
> @@ -1369,7 +1364,7 @@ static int max9286_probe(struct i2c_client *client)
>         if (ret)
>                 goto err_powerdown;
> =20
> -       ret =3D max9286_init(&client->dev);
> +       ret =3D max9286_init(priv);
>         if (ret < 0)
>                 goto err_cleanup_dt;
> =20
> @@ -1385,7 +1380,7 @@ static int max9286_probe(struct i2c_client *client)
> =20
>  static int max9286_remove(struct i2c_client *client)
>  {
> -       struct max9286_priv *priv =3D i2c_get_clientdata(client);
> +       struct max9286_priv *priv =3D sd_to_max9286(i2c_get_clientdata(cl=
ient));
> =20
>         i2c_mux_del_adapters(priv->mux);
> =20
> --=20
> 2.17.1
>