On Thu, Sep 10, 2009 at 09:30:03AM -0600, Jonathan Corbet wrote:
> On Thu, 10 Sep 2009 18:37:34 +0000
> iceberg <str...@ispras.ru> wrote:
>
> > In ./drivers/media/video/cafe_ccic.c, in function cafe_pci_probe:
> > Mutex must be unlocked before exit
> > 1. On paths starting with mutex lock in line 1912, then continuing in
> > lines:
> > 1929, 1936 (goto unreg) and 1940 (goto iounmap) .
> > 2. On path starting in line 1971 mutex lock, and then continuing in
> > line 1978
> > (goto out_smbus) mutex.
>
> That's a definite bug, but I hate all those unlocks in the error
> branches. As it happens, we don't really need the mutex until the
> device has been exposed to the rest of the kernel, so I propose the
> following as a better patch.
>
> Thanks for pointing this out,
Actually, for something like this, I would put the mutex_unlock in the error
path,
and just add a local variable to tell that it is locked.
int is_locked = 0;
[...]
mutex_lock(&cam->s_mutex);
is_locked = 1;
[...]
mutex_unlock(&cam->s_mutex);
is_locked = 0;
[...]
out_iounmap:
pci_iounmap(pdev, cam->regs);
if (is_locked)
mutex_unlock(&cam->s_mutex);
out_free:
[...]
Or something similar. I hate the multiple unlocks too.
-- Steve
>
> jon
>
> ---
> Fix a mutex leak
>
> Certain error exits from cafe_pci_probe() can leave the camera mutex
> locked. For much of the time, we didn't need the mutex anyway; take it out
> and add an unlock in the path where it is needed.
>
> Reported-by: Alexander Strakh <str...@ispras.ru>
> Signed-off-by: Jonathan Corbet <cor...@lwn.net>
> ---
> drivers/media/video/cafe_ccic.c | 3 +--
> 1 files changed, 1 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/media/video/cafe_ccic.c b/drivers/media/video/cafe_ccic.c
> index c4d181d..0f62b5e 100644
> --- a/drivers/media/video/cafe_ccic.c
> +++ b/drivers/media/video/cafe_ccic.c
> @@ -1909,7 +1909,6 @@ static int cafe_pci_probe(struct pci_dev *pdev,
> goto out_free;
>
> mutex_init(&cam->s_mutex);
> - mutex_lock(&cam->s_mutex);
> spin_lock_init(&cam->dev_lock);
> cam->state = S_NOTREADY;
> cafe_set_config_needed(cam, 1);
> @@ -1949,7 +1948,6 @@ static int cafe_pci_probe(struct pci_dev *pdev,
> * because the sensor could attach in this call chain, leading to
> * unsightly deadlocks.
> */
> - mutex_unlock(&cam->s_mutex); /* attach can deadlock */
> ret = cafe_smbus_setup(cam);
> if (ret)
> goto out_freeirq;
> @@ -1991,6 +1989,7 @@ static int cafe_pci_probe(struct pci_dev *pdev,
> return 0;
>
> out_smbus:
> + mutex_unlock(&cam->s_mutex);
> cafe_smbus_shutdown(cam);
> out_freeirq:
> cafe_ctlr_power_down(cam);
> --
> 1.6.2.5
>
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