[PATCH v2] console: console: Complete exception handling in newport_probe()

[PATCH v2] console: console: Complete exception handling in newport_probe()

[Dejin Zheng]

A call of the function ¡°do_take_over_console¡± can fail here.
The corresponding system resources were not released then.
Thus add a call of the function ¡°iounmap¡± together with the check
of a failure predicate.

Fixes: e84de0c6190503 ("MIPS: GIO bus support for SGI IP22/28")
CC: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Dejin Zheng <zhengdejin5@gmail.com>
---
v1 -> v2:
	- modify the commit comments by Markus'suggestion.

 drivers/video/console/newport_con.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/video/console/newport_con.c b/drivers/video/console/newport_con.c
index 00dddf6e08b0..6bfc8e3ffd4a 100644
--- a/drivers/video/console/newport_con.c
+++ b/drivers/video/console/newport_con.c
@@ -720,6 +720,9 @@ static int newport_probe(struct gio_device *dev,
 	console_lock();
 	err = do_take_over_console(&newport_con, 0, MAX_NR_CONSOLES - 1, 1);
 	console_unlock();
+
+	if (err)
+		iounmap((void *)npregs);
 	return err;
 }
 
-- 
2.25.0

Re: [PATCH v2] console: console: Complete exception handling in newport_probe()

[Andy Shevchenko]

On Thu, Apr 23, 2020 at 5:26 PM Dejin Zheng <zhengdejin5@gmail.com> wrote:
>
> A call of the function ¡°do_take_over_console¡± can fail here.
> The corresponding system resources were not released then.
> Thus add a call of the function ¡°iounmap¡± together with the check
> of a failure predicate.

...

> CC: Andy Shevchenko <andy.shevchenko@gmail.com>

Use Cc: Better to read.

...

> v1 -> v2:
>         - modify the commit comments by Markus'suggestion.

What suggestion? You need to be clear in changelog what exactly has
been done without looking to any previous mail.

...

>         console_lock();
>         err = do_take_over_console(&newport_con, 0, MAX_NR_CONSOLES - 1, 1);
>         console_unlock();
> +
> +       if (err)
> +               iounmap((void *)npregs);
>         return err;
>  }

I have briefly looked at the code (it is actually quite old one!), and
I think this is half-baked solution, besides the fact of missed
__iomem annotation and useless explicit casting.
The proper one seems to switch to memremap() and do memunmap() here.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v2] console: console: Complete exception handling in newport_probe()

[Dejin Zheng]

On Thu, Apr 23, 2020 at 05:52:09PM +0300, Andy Shevchenko wrote:
> On Thu, Apr 23, 2020 at 5:26 PM Dejin Zheng <zhengdejin5@gmail.com> wrote:
> >
> > A call of the function do_take_over_console() can fail here.
> > The corresponding system resources were not released then.
> > Thus add a call of the function iounmap() together with the check
> > of a failure predicate.
> 
> ...
> 
> > CC: Andy Shevchenko <andy.shevchenko@gmail.com>
> 
> Use Cc: Better to read.
>
I will pay attention to the next submission, thanks.

> ...
> 
> > v1 -> v2:
> >         - modify the commit comments by Markus'suggestion.
> 
> What suggestion? You need to be clear in changelog what exactly has
> been done without looking to any previous mail.
>
The commit comments have some more appropriate instructions by
Markus'suggestion. here is my first version commit comments:

if do_take_over_console() return an error in the newport_probe(),
due to the io virtual address is not released, it will cause a leak.

Thnaks!

> ...
> 
> >         console_lock();
> >         err = do_take_over_console(&newport_con, 0, MAX_NR_CONSOLES - 1, 1);
> >         console_unlock();
> > +
> > +       if (err)
> > +               iounmap((void *)npregs);
> >         return err;
> >  }
> 
> I have briefly looked at the code (it is actually quite old one!), and
> I think this is half-baked solution, besides the fact of missed
> __iomem annotation and useless explicit casting.
> The proper one seems to switch to memremap() and do memunmap() here.
> 
> -- 
> With Best Regards,
> Andy Shevchenko

Re: [PATCH v2] console: console: Complete exception handling in newport_probe()

[Bartlomiej Zolnierkiewicz]

Hi,

I believe that the patch summary line should be:

"[PATCH v2] console: newport_con: ..."

On 4/23/20 4:26 PM, Dejin Zheng wrote:
> A call of the function ¡°do_take_over_console¡± can fail here.
> The corresponding system resources were not released then.
> Thus add a call of the function ¡°iounmap¡± together with the check
> of a failure predicate.
> 
> Fixes: e84de0c6190503 ("MIPS: GIO bus support for SGI IP22/28")

I cannot see how this patch fixes commit e84de0c6190503
(AFAICS npregs has also been leaked on error before)?

> CC: Andy Shevchenko <andy.shevchenko@gmail.com>
> Signed-off-by: Dejin Zheng <zhengdejin5@gmail.com>
> ---
> v1 -> v2:
> 	- modify the commit comments by Markus'suggestion.
> 
>  drivers/video/console/newport_con.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/video/console/newport_con.c b/drivers/video/console/newport_con.c
> index 00dddf6e08b0..6bfc8e3ffd4a 100644
> --- a/drivers/video/console/newport_con.c
> +++ b/drivers/video/console/newport_con.c
> @@ -720,6 +720,9 @@ static int newport_probe(struct gio_device *dev,
>  	console_lock();
>  	err = do_take_over_console(&newport_con, 0, MAX_NR_CONSOLES - 1, 1);
>  	console_unlock();
> +
> +	if (err)
> +		iounmap((void *)npregs);

Looks OK but while you are at it, could you please also add missing
release_mem_region() on error and on device removal:

	newport_addr = dev->resource.start + 0xF0000;
	if (!request_mem_region(newport_addr, 0x10000, "Newport"))
		return -ENODEV;

	npregs = (struct newport_regs *)/* ioremap cannot fail */
		ioremap(newport_addr, sizeof(struct newport_regs));
	console_lock();
	err = do_take_over_console(&newport_con, 0, MAX_NR_CONSOLES - 1, 1);
	console_unlock();
	return err;
}

static void newport_remove(struct gio_device *dev)
{
	give_up_console(&newport_con);
	iounmap((void *)npregs);
}

?

>  	return err;
>  }
>  

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics

Re: [PATCH v2] console: console: Complete exception handling in newport_probe()

[Andy Shevchenko]

On Thu, Apr 23, 2020 at 5:55 PM Bartlomiej Zolnierkiewicz
<b.zolnierkie@samsung.com> wrote:

> > +     if (err)
> > +             iounmap((void *)npregs);
>
> Looks OK but while you are at it, could you please also add missing
> release_mem_region() on error and on device removal:
>
>         newport_addr = dev->resource.start + 0xF0000;
>         if (!request_mem_region(newport_addr, 0x10000, "Newport"))
>                 return -ENODEV;
>
>         npregs = (struct newport_regs *)/* ioremap cannot fail */
>                 ioremap(newport_addr, sizeof(struct newport_regs));
>         console_lock();
>         err = do_take_over_console(&newport_con, 0, MAX_NR_CONSOLES - 1, 1);
>         console_unlock();
>         return err;
> }
>
> static void newport_remove(struct gio_device *dev)
> {
>         give_up_console(&newport_con);
>         iounmap((void *)npregs);
> }
>
> ?

Don't you think that proper solution is rather switch to memremap()?

> >       return err;
> >  }

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v2] console: console: Complete exception handling in newport_probe()

[Bartlomiej Zolnierkiewicz]

On 4/23/20 5:05 PM, Andy Shevchenko wrote:
> On Thu, Apr 23, 2020 at 5:55 PM Bartlomiej Zolnierkiewicz
> <b.zolnierkie@samsung.com> wrote:
> 
>>> +     if (err)
>>> +             iounmap((void *)npregs);
>>
>> Looks OK but while you are at it, could you please also add missing
>> release_mem_region() on error and on device removal:
>>
>>         newport_addr = dev->resource.start + 0xF0000;
>>         if (!request_mem_region(newport_addr, 0x10000, "Newport"))
>>                 return -ENODEV;
>>
>>         npregs = (struct newport_regs *)/* ioremap cannot fail */
>>                 ioremap(newport_addr, sizeof(struct newport_regs));
>>         console_lock();
>>         err = do_take_over_console(&newport_con, 0, MAX_NR_CONSOLES - 1, 1);
>>         console_unlock();
>>         return err;
>> }
>>
>> static void newport_remove(struct gio_device *dev)
>> {
>>         give_up_console(&newport_con);
>>         iounmap((void *)npregs);
>> }
>>
>> ?
> 
> Don't you think that proper solution is rather switch to memremap()?

Doesn't seem to be a case here (used memory region in uncached).

On MIPS (this is MIPS-only driver):

...
#define ioremap(offset, size)						\
	__ioremap_mode((offset), (size), _CACHE_UNCACHED)
#define ioremap_uc		ioremap
...

While memremap() is only for cacheable memory:

...
 * memremap() - remap an iomem_resource as cacheable memory
 * @offset: iomem resource start address
 * @size: size of remap
 * @flags: any of MEMREMAP_WB, MEMREMAP_WT, MEMREMAP_WC,
 *		  MEMREMAP_ENC, MEMREMAP_DEC
...


>>>       return err;
>>>  }
> 
 
Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics

Re: [PATCH v2] console: console: Complete exception handling in newport_probe()

[Dejin Zheng]

On Thu, Apr 23, 2020 at 04:55:35PM +0200, Bartlomiej Zolnierkiewicz wrote:
> 
> Hi,
> 
> I believe that the patch summary line should be:
> 
> "[PATCH v2] console: newport_con: ..."
>
OK, thanks!

> On 4/23/20 4:26 PM, Dejin Zheng wrote:
> > A call of the function ¡°do_take_over_console¡± can fail here.
> > The corresponding system resources were not released then.
> > Thus add a call of the function ¡°iounmap¡± together with the check
> > of a failure predicate.
> > 
> > Fixes: e84de0c6190503 ("MIPS: GIO bus support for SGI IP22/28")
>
> I cannot see how this patch fixes commit e84de0c6190503
> (AFAICS npregs has also been leaked on error before)?
>
yes, you are right, the commit should be e86bb8acc0fdca82d2
("[PATCH] VT binding: Make newport_con support binding")

- move register ioremap from newport_startup() to newport_console_init()

> > CC: Andy Shevchenko <andy.shevchenko@gmail.com>
> > Signed-off-by: Dejin Zheng <zhengdejin5@gmail.com>
> > ---
> > v1 -> v2:
> > 	- modify the commit comments by Markus'suggestion.
> > 
> >  drivers/video/console/newport_con.c | 3 +++
> >  1 file changed, 3 insertions(+)
> > 
> > diff --git a/drivers/video/console/newport_con.c b/drivers/video/console/newport_con.c
> > index 00dddf6e08b0..6bfc8e3ffd4a 100644
> > --- a/drivers/video/console/newport_con.c
> > +++ b/drivers/video/console/newport_con.c
> > @@ -720,6 +720,9 @@ static int newport_probe(struct gio_device *dev,
> >  	console_lock();
> >  	err = do_take_over_console(&newport_con, 0, MAX_NR_CONSOLES - 1, 1);
> >  	console_unlock();
> > +
> > +	if (err)
> > +		iounmap((void *)npregs);
> 
> Looks OK but while you are at it, could you please also add missing
> release_mem_region() on error and on device removal:
>
Ok, Thanks, I will send the patch v3 for it.

> 	newport_addr = dev->resource.start + 0xF0000;
> 	if (!request_mem_region(newport_addr, 0x10000, "Newport"))
> 		return -ENODEV;
> 
> 	npregs = (struct newport_regs *)/* ioremap cannot fail */
> 		ioremap(newport_addr, sizeof(struct newport_regs));
> 	console_lock();
> 	err = do_take_over_console(&newport_con, 0, MAX_NR_CONSOLES - 1, 1);
> 	console_unlock();
> 	return err;
> }
> 
> static void newport_remove(struct gio_device *dev)
> {
> 	give_up_console(&newport_con);
> 	iounmap((void *)npregs);
> }
> 
> ?
> 
> >  	return err;
> >  }
> >  
> 
> Best regards,
> --
> Bartlomiej Zolnierkiewicz
> Samsung R&D Institute Poland
> Samsung Electronics