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 <[email protected]>
Fixes: 23c7b54ca1cd ("PM / devfreq: Fix devfreq_add_device() when drivers are built as modules.")
Reported-by: Alyssa Rosenzweig <[email protected]>
Cc: Enric Balletbo i Serra <[email protected]>
---
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);
}
--
2.20.1
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 <[email protected]>
> Fixes: 23c7b54ca1cd ("PM / devfreq: Fix devfreq_add_device() when drivers are built as modules.")
> Reported-by: Alyssa Rosenzweig <[email protected]>
> Cc: Enric Balletbo i Serra <[email protected]>
> ---
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);
> }
>
On Tue, 23 Apr 2019 at 11:56, Enric Balletbo i Serra
<[email protected]> wrote:
>
> 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 <[email protected]>
> > Fixes: 23c7b54ca1cd ("PM / devfreq: Fix devfreq_add_device() when drivers are built as modules.")
> > Reported-by: Alyssa Rosenzweig <[email protected]>
> > Cc: Enric Balletbo i Serra <[email protected]>
> > ---
>
> 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.
Actually, Steve Price sent a third patch for this same issue.
Glad to read that it's being merged.
Thanks,
Tomeu
> 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);
> > }
> >