diff mbox

drm/msm/dsi: free first element on error

Message ID 20170216105042.GA25544@mwanda (mailing list archive)
State New, archived
Headers show

Commit Message

Dan Carpenter Feb. 16, 2017, 10:50 a.m. UTC
We want to free msm_host->bus_clks[0] so the > should be >=.

Fixes: 6e0eb52eba9e ("drm/msm/dsi: Parse bus clocks from a list")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

Comments

Jani Nikula Feb. 16, 2017, 11:27 a.m. UTC | #1
On Thu, 16 Feb 2017, Dan Carpenter <dan.carpenter@oracle.com> wrote:
> We want to free msm_host->bus_clks[0] so the > should be >=.
>
> Fixes: 6e0eb52eba9e ("drm/msm/dsi: Parse bus clocks from a list")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
>
> diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c
> index 1fc07ce24686..239e79b39a45 100644
> --- a/drivers/gpu/drm/msm/dsi/dsi_host.c
> +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
> @@ -437,7 +437,7 @@ static int dsi_bus_clk_enable(struct msm_dsi_host *msm_host)
>  
>  	return 0;
>  err:
> -	for (; i > 0; i--)
> +	for (; i >= 0; i--)
>  		clk_disable_unprepare(msm_host->bus_clks[i]);

By the looks of it this is also wrong. I didn't look at the functions,
but you probably don't want to unprepare something where prepare failed,
i.e. you want to -1 both the start and end offsets. Perhaps the right
fix is

	while (i--)
		clk_disable_unprepare(msm_host->bus_clks[i]);

which also seems to be widely used on error paths.

BR,
Jani.


>  
>  	return ret;
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel
Dan Carpenter Feb. 16, 2017, 11:53 a.m. UTC | #2
On Thu, Feb 16, 2017 at 01:27:47PM +0200, Jani Nikula wrote:
> On Thu, 16 Feb 2017, Dan Carpenter <dan.carpenter@oracle.com> wrote:
> > We want to free msm_host->bus_clks[0] so the > should be >=.
> >
> > Fixes: 6e0eb52eba9e ("drm/msm/dsi: Parse bus clocks from a list")
> > Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> >
> > diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c
> > index 1fc07ce24686..239e79b39a45 100644
> > --- a/drivers/gpu/drm/msm/dsi/dsi_host.c
> > +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
> > @@ -437,7 +437,7 @@ static int dsi_bus_clk_enable(struct msm_dsi_host *msm_host)
> >  
> >  	return 0;
> >  err:
> > -	for (; i > 0; i--)
> > +	for (; i >= 0; i--)
> >  		clk_disable_unprepare(msm_host->bus_clks[i]);
> 
> By the looks of it this is also wrong. I didn't look at the functions,
> but you probably don't want to unprepare something where prepare failed,
> i.e. you want to -1 both the start and end offsets. Perhaps the right
> fix is
> 
> 	while (i--)
> 		clk_disable_unprepare(msm_host->bus_clks[i]);
> 
> which also seems to be widely used on error paths.
> 

Ah yeah.  You're right.  I'll resend.

regards,
dan carpenter
Walter Harms Feb. 16, 2017, 12:03 p.m. UTC | #3
Am 16.02.2017 12:53, schrieb Dan Carpenter:
> On Thu, Feb 16, 2017 at 01:27:47PM +0200, Jani Nikula wrote:
>> On Thu, 16 Feb 2017, Dan Carpenter <dan.carpenter@oracle.com> wrote:
>>> We want to free msm_host->bus_clks[0] so the > should be >=.
>>>
>>> Fixes: 6e0eb52eba9e ("drm/msm/dsi: Parse bus clocks from a list")
>>> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
>>>
>>> diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c
>>> index 1fc07ce24686..239e79b39a45 100644
>>> --- a/drivers/gpu/drm/msm/dsi/dsi_host.c
>>> +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
>>> @@ -437,7 +437,7 @@ static int dsi_bus_clk_enable(struct msm_dsi_host *msm_host)
>>>  
>>>  	return 0;
>>>  err:
>>> -	for (; i > 0; i--)
>>> +	for (; i >= 0; i--)
>>>  		clk_disable_unprepare(msm_host->bus_clks[i]);
>>
>> By the looks of it this is also wrong. I didn't look at the functions,
>> but you probably don't want to unprepare something where prepare failed,
>> i.e. you want to -1 both the start and end offsets. Perhaps the right
>> fix is
>>
>> 	while (i--)
>> 		clk_disable_unprepare(msm_host->bus_clks[i]);
>>
>> which also seems to be widely used on error paths.
>>
> 

We already know that programmers are bad in counting backwards ...

any chance to make that into a forward loop ?

re,
 wh
Rob Clark Feb. 16, 2017, 12:15 p.m. UTC | #4
On Thu, Feb 16, 2017 at 7:03 AM, walter harms <wharms@bfs.de> wrote:
>
>
> Am 16.02.2017 12:53, schrieb Dan Carpenter:
>> On Thu, Feb 16, 2017 at 01:27:47PM +0200, Jani Nikula wrote:
>>> On Thu, 16 Feb 2017, Dan Carpenter <dan.carpenter@oracle.com> wrote:
>>>> We want to free msm_host->bus_clks[0] so the > should be >=.
>>>>
>>>> Fixes: 6e0eb52eba9e ("drm/msm/dsi: Parse bus clocks from a list")
>>>> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
>>>>
>>>> diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c
>>>> index 1fc07ce24686..239e79b39a45 100644
>>>> --- a/drivers/gpu/drm/msm/dsi/dsi_host.c
>>>> +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
>>>> @@ -437,7 +437,7 @@ static int dsi_bus_clk_enable(struct msm_dsi_host *msm_host)
>>>>
>>>>     return 0;
>>>>  err:
>>>> -   for (; i > 0; i--)
>>>> +   for (; i >= 0; i--)
>>>>             clk_disable_unprepare(msm_host->bus_clks[i]);
>>>
>>> By the looks of it this is also wrong. I didn't look at the functions,
>>> but you probably don't want to unprepare something where prepare failed,
>>> i.e. you want to -1 both the start and end offsets. Perhaps the right
>>> fix is
>>>
>>>      while (i--)
>>>              clk_disable_unprepare(msm_host->bus_clks[i]);
>>>
>>> which also seems to be widely used on error paths.
>>>
>>
>
> We already know that programmers are bad in counting backwards ...
>
> any chance to make that into a forward loop ?
>

well, this *is* a common pattern.  And in some cases you actually do
need to disable clks in reverse order.  So meh, I think while (i--)
approach is fine

BR,
-R
Jani Nikula Feb. 16, 2017, 12:25 p.m. UTC | #5
On Thu, 16 Feb 2017, walter harms <wharms@bfs.de> wrote:
> Am 16.02.2017 12:53, schrieb Dan Carpenter:
>> On Thu, Feb 16, 2017 at 01:27:47PM +0200, Jani Nikula wrote:
>>> On Thu, 16 Feb 2017, Dan Carpenter <dan.carpenter@oracle.com> wrote:
>>>> We want to free msm_host->bus_clks[0] so the > should be >=.
>>>>
>>>> Fixes: 6e0eb52eba9e ("drm/msm/dsi: Parse bus clocks from a list")
>>>> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
>>>>
>>>> diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c
>>>> index 1fc07ce24686..239e79b39a45 100644
>>>> --- a/drivers/gpu/drm/msm/dsi/dsi_host.c
>>>> +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
>>>> @@ -437,7 +437,7 @@ static int dsi_bus_clk_enable(struct msm_dsi_host *msm_host)
>>>>  
>>>>  	return 0;
>>>>  err:
>>>> -	for (; i > 0; i--)
>>>> +	for (; i >= 0; i--)
>>>>  		clk_disable_unprepare(msm_host->bus_clks[i]);
>>>
>>> By the looks of it this is also wrong. I didn't look at the functions,
>>> but you probably don't want to unprepare something where prepare failed,
>>> i.e. you want to -1 both the start and end offsets. Perhaps the right
>>> fix is
>>>
>>> 	while (i--)
>>> 		clk_disable_unprepare(msm_host->bus_clks[i]);
>>>
>>> which also seems to be widely used on error paths.
>>>
>> 
>
> We already know that programmers are bad in counting backwards ...
>
> any chance to make that into a forward loop ?

In most cases I'd agree with you. But I see that this while (i--) is
becoming somewhat of a pattern for error paths (grep for it), and I
think following patterns like this is more important. After a while, you
don't have to think about counting when you see it.

Besides, it's generally preferred to cleanup in the reverse order of
init, so a forward counting loop would require two variables here.

BR,
Jani.



>
> re,
>  wh
>
>
diff mbox

Patch

diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c
index 1fc07ce24686..239e79b39a45 100644
--- a/drivers/gpu/drm/msm/dsi/dsi_host.c
+++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
@@ -437,7 +437,7 @@  static int dsi_bus_clk_enable(struct msm_dsi_host *msm_host)
 
 	return 0;
 err:
-	for (; i > 0; i--)
+	for (; i >= 0; i--)
 		clk_disable_unprepare(msm_host->bus_clks[i]);
 
 	return ret;