Re: [PATCH] fix lock imbalances in /drivers/media/video/cafe_ccic.c
From: iceberg
Date: Fri Sep 11 2009 - 09:46:18 EST
On Thursday 10 September 2009 15:30:03 you wrote:
Incorrect patch. See path starting with "if (cam->sensor == null) {" in line
1960. In this case we goto out_smbs and try mutex_unlock on unlocking mutex.
>
On 2009年9月10日 18:37:34 +0000
>
>
iceberg <strakh@xxxxxxxxx> 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,
>
>
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 <strakh@xxxxxxxxx>
>
Signed-off-by: Jonathan Corbet <corbet@xxxxxxx>
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---
>
drivers/media/video/cafe_ccic.c | 3 +--
>
1 files changed, 1 insertions(+), 2 deletions(-)
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>
diff --git a/drivers/media/video/cafe_ccic.c
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b/drivers/media/video/cafe_ccic.c index c4d181d..0f62b5e 100644
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--- a/drivers/media/video/cafe_ccic.c
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+++ b/drivers/media/video/cafe_ccic.c
>
@@ -1909,7 +1909,6 @@ static int cafe_pci_probe(struct pci_dev *pdev,
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goto out_free;
>
>
mutex_init(&cam->s_mutex);
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- mutex_lock(&cam->s_mutex);
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spin_lock_init(&cam->dev_lock);
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cam->state = S_NOTREADY;
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cafe_set_config_needed(cam, 1);
>
@@ -1949,7 +1948,6 @@ static int cafe_pci_probe(struct pci_dev *pdev,
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* because the sensor could attach in this call chain, leading to
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* unsightly deadlocks.
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*/
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- mutex_unlock(&cam->s_mutex); /* attach can deadlock */
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ret = cafe_smbus_setup(cam);
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if (ret)
>
goto out_freeirq;
>
@@ -1991,6 +1989,7 @@ static int cafe_pci_probe(struct pci_dev *pdev,
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return 0;
>
>
out_smbus:
>
+ mutex_unlock(&cam->s_mutex);
>
cafe_smbus_shutdown(cam);
>
out_freeirq:
>
cafe_ctlr_power_down(cam);
--
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