[patch 2/2] w1: unlock correct lock on error in w1_seq_show()

[patch 2/2] w1: unlock correct lock on error in w1_seq_show()

[Dan Carpenter]

Smatch complains that we don't unlock "master->mutex" on this error
path.  It looks like it is a typo and we unlock ->bus_mutext where
->mutex was intended.

Fixes: d9411e57dc7f ('w1: Add support for DS28EA00 sequence to w1-therm')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

diff --git a/drivers/w1/slaves/w1_therm.c b/drivers/w1/slaves/w1_therm.c
index 3351be6..79ecaf8 100644
--- a/drivers/w1/slaves/w1_therm.c
+++ b/drivers/w1/slaves/w1_therm.c
@@ -412,7 +412,7 @@ static ssize_t w1_seq_show(struct device *device,
 	c -= snprintf(buf + PAGE_SIZE - c, c, "%d\n", seq);
 	return PAGE_SIZE - c;
 error:
-	mutex_unlock(&sl->master->bus_mutex);
+	mutex_unlock(&sl->master->mutex);
 	return -EIO;
 }
 

Re: [patch 2/2] w1: unlock correct lock on error in w1_seq_show()

[David Fries]

Thanks for including me, I'm going to have to nack this though, it is
an error, but bus_mutex is correct, mutex is incorrect, so the other
two lock/unlock in that routine are the ones that need to be changed.

w1.h
 * @mutex:              protect most of w1_master
 * @bus_mutex:          pretect concurrent bus access

On Mon, Jun 01, 2015 at 12:56:32PM +0300, Dan Carpenter wrote:
> Smatch complains that we don't unlock "master->mutex" on this error
> path.  It looks like it is a typo and we unlock ->bus_mutext where
> ->mutex was intended.
> 
> Fixes: d9411e57dc7f ('w1: Add support for DS28EA00 sequence to w1-therm')
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> 
> diff --git a/drivers/w1/slaves/w1_therm.c b/drivers/w1/slaves/w1_therm.c
> index 3351be6..79ecaf8 100644
> --- a/drivers/w1/slaves/w1_therm.c
> +++ b/drivers/w1/slaves/w1_therm.c
> @@ -412,7 +412,7 @@ static ssize_t w1_seq_show(struct device *device,
>  	c -= snprintf(buf + PAGE_SIZE - c, c, "%d\n", seq);
>  	return PAGE_SIZE - c;
>  error:
> -	mutex_unlock(&sl->master->bus_mutex);
> +	mutex_unlock(&sl->master->mutex);
>  	return -EIO;
>  }
>  

-- 
David Fries <david@fries.net>

[patch] [patch 2/2 v2] w1: use correct lock on error in w1_seq_show()

[Dan Carpenter]

I noticed there was a problem here because Smatch complained:

	drivers/w1/slaves/w1_therm.c:416 w1_seq_show() warn:
	inconsistent returns 'mutex:&sl->master->mutex'.
	  Locked on:   line 416
	  Unlocked on: line 413

The problem is that we lock ->mutex but we unlock ->bus_mutex on error.
David Fries says that ->bus_mutex is correct and ->mutex is incorrect.

Fixes: d9411e57dc7f ('w1: Add support for DS28EA00 sequence to w1-therm')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
v2: In the first version I changed ->bus_mutext to ->mutex instead of
    the other way around.

diff --git a/drivers/w1/slaves/w1_therm.c b/drivers/w1/slaves/w1_therm.c
index d21e686..06b034c 100644
--- a/drivers/w1/slaves/w1_therm.c
+++ b/drivers/w1/slaves/w1_therm.c
@@ -355,7 +355,7 @@ static ssize_t w1_seq_show(struct device *device,
 	struct w1_reg_num *reg_num;
 	int seq = 0;
 
-	mutex_lock(&sl->master->mutex);
+	mutex_lock(&sl->master->bus_mutex);
 	/* Place all devices in CHAIN state */
 	if (w1_reset_bus(sl->master))
 		goto error;
@@ -407,7 +407,7 @@ static ssize_t w1_seq_show(struct device *device,
 	ack = w1_read_8(sl->master);
 	if (ack != W1_42_SUCCESS_CONFIRM_BYTE)
 		goto error;
-	mutex_unlock(&sl->master->mutex);
+	mutex_unlock(&sl->master->bus_mutex);
 
 	c -= snprintf(buf + PAGE_SIZE - c, c, "%d\n", seq);
 	return PAGE_SIZE - c;

Re: [patch] [patch 2/2 v2] w1: use correct lock on error in w1_seq_show()

[Evgeniy Polyakov]

Hi

04.06.2015, 12:04, "Dan Carpenter" <dan.carpenter@oracle.com>:
> I noticed there was a problem here because Smatch complained:
>
> ššššššššdrivers/w1/slaves/w1_therm.c:416 w1_seq_show() warn:
> ššššššššinconsistent returns 'mutex:&sl->master->mutex'.
> ššššššššššLocked on: line 416
> ššššššššššUnlocked on: line 413
>
> The problem is that we lock ->mutex but we unlock ->bus_mutex on error.
> David Fries says that ->bus_mutex is correct and ->mutex is incorrect.
>
> Fixes: d9411e57dc7f ('w1: Add support for DS28EA00 sequence to w1-therm')
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

Looks good to me, Greg please pull this serie into your tree, if you hadn't yet.
Am I right that this is a stable tree material too?

Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
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Re: [patch] [patch 2/2 v2] w1: use correct lock on error in w1_seq_show()

[David Fries]

On Thu, Jun 11, 2015 at 06:31:00PM +0300, Evgeniy Polyakov wrote:
> Hi
> 
> 04.06.2015, 12:04, "Dan Carpenter" <dan.carpenter@oracle.com>:
> > I noticed there was a problem here because Smatch complained:
> >
> >         drivers/w1/slaves/w1_therm.c:416 w1_seq_show() warn:
> >         inconsistent returns 'mutex:&sl->master->mutex'.
> >           Locked on: line 416
> >           Unlocked on: line 413
> >
> > The problem is that we lock ->mutex but we unlock ->bus_mutex on error.
> > David Fries says that ->bus_mutex is correct and ->mutex is incorrect.
> >
> > Fixes: d9411e57dc7f ('w1: Add support for DS28EA00 sequence to w1-therm')
> > Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> 
> Looks good to me, Greg please pull this serie into your tree, if you hadn't yet.
> Am I right that this is a stable tree material too?

I would expect the answer to be no.  This is a fix to a new feature
that is in gregkh/char-misc but not yet in Linus's tree.

-- 
David Fries <david@fries.net>
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