From: Enric Balletbo i Serra <enric.balletbo@collabora.com>
To: Tomeu Vizoso <tomeu.vizoso@collabora.com>, linux-kernel@vger.kernel.org
Cc: Alyssa Rosenzweig <alyssa@rosenzweig.io>,
MyungJoo Ham <myungjoo.ham@samsung.com>,
Kyungmin Park <kyungmin.park@samsung.com>,
Chanwoo Choi <cw00.choi@samsung.com>,
linux-pm@vger.kernel.org
Subject: Re: [PATCH] PM / devfreq: Return -ENODEV from try_then_request_governor
Date: Tue, 23 Apr 2019 11:55:52 +0200 [thread overview]
Message-ID: <ed7c20b9-b435-5f40-55ab-97d6384749f1@collabora.com> (raw)
In-Reply-To: <20190423081158.29859-1-tomeu.vizoso@collabora.com>
Hi Tomeu,
On 23/4/19 10:11, Tomeu Vizoso wrote:
> Callers don't expect it to return NULL, but an error code.
>
> Fixes Oops such as the one below, when one tries to set a governor that
> isn't available:
>
> Unable to handle kernel NULL pointer dereference at virtual address 00000018
>
> [<c0dcf718>] (governor_store) from [<c0539558>] (kernfs_fop_write+0x100/0x1e0)
> [<c0539558>] (kernfs_fop_write) from [<c04b09b4>] (__vfs_write+0x2c/0x17c)
> [<c04b09b4>] (__vfs_write) from [<c04b33fc>] (vfs_write+0xa4/0x184)
> [<c04b33fc>] (vfs_write) from [<c04b361c>] (ksys_write+0x4c/0xac)
> [<c04b361c>] (ksys_write) from [<c0301000>] (ret_fast_syscall+0x0/0x28)
>
> Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
> Fixes: 23c7b54ca1cd ("PM / devfreq: Fix devfreq_add_device() when drivers are built as modules.")
> Reported-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
> Cc: Enric Balletbo i Serra <enric.balletbo@collabora.com>
> ---
There is already a fix for that. The fix was initially sent in October [2] but
unfortunately it got lost. I resend and now is queued [1]. Hopefully the Fixes
tag will help to pick the fix to the proper kernel releases.
Thanks,
Enric
[1]
https://git.kernel.org/pub/scm/linux/kernel/git/mzx/devfreq.git/commit/?h=for-next&id=b53b0128052ffd687797d5f4deeb76327e7b5711
[2] https://lkml.org/lkml/2018/10/16/744
> drivers/devfreq/devfreq.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> index 0ae3de76833b..5539e9be718d 100644
> --- a/drivers/devfreq/devfreq.c
> +++ b/drivers/devfreq/devfreq.c
> @@ -254,7 +254,7 @@ static struct devfreq_governor *try_then_request_governor(const char *name)
> /* Restore previous state before return */
> mutex_lock(&devfreq_list_lock);
> if (err)
> - return NULL;
> + return ERR_PTR(-ENODEV);
>
> governor = find_devfreq_governor(name);
> }
>
next prev parent reply other threads:[~2019-04-23 9:55 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-23 8:11 [PATCH] PM / devfreq: Return -ENODEV from try_then_request_governor Tomeu Vizoso
2019-04-23 9:55 ` Enric Balletbo i Serra [this message]
2019-04-24 5:34 ` Tomeu Vizoso
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