[PATCH] tty/serial: digicolor: Fix bad usage of IS_ERR_VALUE

[PATCH] tty/serial: digicolor: Fix bad usage of IS_ERR_VALUE

[Guenter Roeck]

IS_ERR_VALUE() assumes that its parameter is an unsigned long.
It can not be used to check if an unsigned int reflects an error.
Doing so can result in the following build warning.

drivers/tty/serial/digicolor-usart.c: In function ‘digicolor_uart_probe’:
include/linux/err.h:21:38: warning:
	comparison is always false due to limited range of data type
drivers/tty/serial/digicolor-usart.c:485:6: note:
	in expansion of macro ‘IS_ERR_VALUE’

If that warning is seen, an error return from platform_get_irq() is missed.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
 drivers/tty/serial/digicolor-usart.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/tty/serial/digicolor-usart.c b/drivers/tty/serial/digicolor-usart.c
index a80cdad114f3..02ad6953b167 100644
--- a/drivers/tty/serial/digicolor-usart.c
+++ b/drivers/tty/serial/digicolor-usart.c
@@ -453,7 +453,7 @@ static struct uart_driver digicolor_uart = {
 static int digicolor_uart_probe(struct platform_device *pdev)
 {
 	struct device_node *np = pdev->dev.of_node;
-	int ret, index;
+	int irq, ret, index;
 	struct digicolor_port *dp;
 	struct resource *res;
 	struct clk *uart_clk;
@@ -481,9 +481,10 @@ static int digicolor_uart_probe(struct platform_device *pdev)
 	if (IS_ERR(dp->port.membase))
 		return PTR_ERR(dp->port.membase);
 
-	dp->port.irq = platform_get_irq(pdev, 0);
-	if (IS_ERR_VALUE(dp->port.irq))
-		return dp->port.irq;
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return irq;
+	dp->port.irq = irq;
 
 	dp->port.iotype = UPIO_MEM;
 	dp->port.uartclk = clk_get_rate(uart_clk);
-- 
2.5.0

Re: [PATCH] tty/serial: digicolor: Fix bad usage of IS_ERR_VALUE

[Arnd Bergmann]

On Tuesday 09 February 2016 07:08:59 Guenter Roeck wrote:
> IS_ERR_VALUE() assumes that its parameter is an unsigned long.
> It can not be used to check if an unsigned int reflects an error.
> Doing so can result in the following build warning.
> 
> drivers/tty/serial/digicolor-usart.c: In function ‘digicolor_uart_probe’:
> include/linux/err.h:21:38: warning:
>         comparison is always false due to limited range of data type
> drivers/tty/serial/digicolor-usart.c:485:6: note:
>         in expansion of macro ‘IS_ERR_VALUE’
> 
> If that warning is seen, an error return from platform_get_irq() is missed.
> 
> 

The patch looks correct to me, but what compiler version and which kernel
tree is it that triggered the warning?

Andrzej Hajda just modified the definition of IS_ERR_VALUE(), and the
changes are still under discussion, but I don't see that warning with
any of the versions.

	Arnd

Re: [PATCH] tty/serial: digicolor: Fix bad usage of IS_ERR_VALUE

[Guenter Roeck]

On 02/09/2016 07:26 AM, Arnd Bergmann wrote:
> On Tuesday 09 February 2016 07:08:59 Guenter Roeck wrote:
>> IS_ERR_VALUE() assumes that its parameter is an unsigned long.
>> It can not be used to check if an unsigned int reflects an error.
>> Doing so can result in the following build warning.
>>
>> drivers/tty/serial/digicolor-usart.c: In function ‘digicolor_uart_probe’:
>> include/linux/err.h:21:38: warning:
>>          comparison is always false due to limited range of data type
>> drivers/tty/serial/digicolor-usart.c:485:6: note:
>>          in expansion of macro ‘IS_ERR_VALUE’
>>
>> If that warning is seen, an error return from platform_get_irq() is missed.
>>
>>
>
> The patch looks correct to me, but what compiler version and which kernel
> tree is it that triggered the warning?
>
> Andrzej Hajda just modified the definition of IS_ERR_VALUE(), and the
> changes are still under discussion, but I don't see that warning with
> any of the versions.
>
I see it with gcc 5.1 and 5.2 (and W=1). I did not see / notice Andrzej's patch.

I agree that fixing the problem in IS_ERR_VALUE() is preferrable.

Guenter

Re: [PATCH] tty/serial: digicolor: Fix bad usage of IS_ERR_VALUE

[Arnd Bergmann]

On Tuesday 09 February 2016 18:37:46 Guenter Roeck wrote:
> On 02/09/2016 07:26 AM, Arnd Bergmann wrote:
> > On Tuesday 09 February 2016 07:08:59 Guenter Roeck wrote:
> >> IS_ERR_VALUE() assumes that its parameter is an unsigned long.
> >> It can not be used to check if an unsigned int reflects an error.
> >> Doing so can result in the following build warning.
> >>
> >> drivers/tty/serial/digicolor-usart.c: In function ‘digicolor_uart_probe’:
> >> include/linux/err.h:21:38: warning:
> >>          comparison is always false due to limited range of data type
> >> drivers/tty/serial/digicolor-usart.c:485:6: note:
> >>          in expansion of macro ‘IS_ERR_VALUE’
> >>
> >> If that warning is seen, an error return from platform_get_irq() is missed.
> >>
> >>
> >
> > The patch looks correct to me, but what compiler version and which kernel
> > tree is it that triggered the warning?
> >
> > Andrzej Hajda just modified the definition of IS_ERR_VALUE(), and the
> > changes are still under discussion, but I don't see that warning with
> > any of the versions.
> >
> I see it with gcc 5.1 and 5.2 (and W=1). I did not see / notice Andrzej's patch.
> 
> I agree that fixing the problem in IS_ERR_VALUE() is preferrable.
> 
> 

Ah, W=1 explains it. We are still debating about the proper solution. Al Viro
pointed out that most users of IS_ERR_VALUE() shouldn't be using it at all,
so your patch is probably best here after all.

	Arnd

Re: [PATCH] tty/serial: digicolor: Fix bad usage of IS_ERR_VALUE

[Guenter Roeck]

On 02/10/2016 07:21 AM, Arnd Bergmann wrote:
> On Tuesday 09 February 2016 18:37:46 Guenter Roeck wrote:
>> On 02/09/2016 07:26 AM, Arnd Bergmann wrote:
>>> On Tuesday 09 February 2016 07:08:59 Guenter Roeck wrote:
>>>> IS_ERR_VALUE() assumes that its parameter is an unsigned long.
>>>> It can not be used to check if an unsigned int reflects an error.
>>>> Doing so can result in the following build warning.
>>>>
>>>> drivers/tty/serial/digicolor-usart.c: In function ‘digicolor_uart_probe’:
>>>> include/linux/err.h:21:38: warning:
>>>>           comparison is always false due to limited range of data type
>>>> drivers/tty/serial/digicolor-usart.c:485:6: note:
>>>>           in expansion of macro ‘IS_ERR_VALUE’
>>>>
>>>> If that warning is seen, an error return from platform_get_irq() is missed.
>>>>
>>>>
>>>
>>> The patch looks correct to me, but what compiler version and which kernel
>>> tree is it that triggered the warning?
>>>
>>> Andrzej Hajda just modified the definition of IS_ERR_VALUE(), and the
>>> changes are still under discussion, but I don't see that warning with
>>> any of the versions.
>>>
>> I see it with gcc 5.1 and 5.2 (and W=1). I did not see / notice Andrzej's patch.
>>
>> I agree that fixing the problem in IS_ERR_VALUE() is preferrable.
>>
>>
>
> Ah, W=1 explains it. We are still debating about the proper solution. Al Viro
> pointed out that most users of IS_ERR_VALUE() shouldn't be using it at all,
> so your patch is probably best here after all.
>

Yes, after looking into it some more I agree. Coccinelle should be able to handle
most of the conversions automatically. I actually tried to write a script, just
for the fun of it, but it misses some of the problem cases in patch mode.
Maybe I get it working tonight.

Guenter

Re: [PATCH] tty/serial: digicolor: Fix bad usage of IS_ERR_VALUE

[Andrzej Hajda]

On 02/11/2016 04:38 AM, Guenter Roeck wrote:
> On 02/10/2016 07:21 AM, Arnd Bergmann wrote:
>> On Tuesday 09 February 2016 18:37:46 Guenter Roeck wrote:
>>> On 02/09/2016 07:26 AM, Arnd Bergmann wrote:
>>>> On Tuesday 09 February 2016 07:08:59 Guenter Roeck wrote:
>>>>> IS_ERR_VALUE() assumes that its parameter is an unsigned long.
>>>>> It can not be used to check if an unsigned int reflects an error.
>>>>> Doing so can result in the following build warning.
>>>>>
>>>>> drivers/tty/serial/digicolor-usart.c: In function ‘digicolor_uart_probe’:
>>>>> include/linux/err.h:21:38: warning:
>>>>>           comparison is always false due to limited range of data type
>>>>> drivers/tty/serial/digicolor-usart.c:485:6: note:
>>>>>           in expansion of macro ‘IS_ERR_VALUE’
>>>>>
>>>>> If that warning is seen, an error return from platform_get_irq() is missed.
>>>>>
>>>>>
>>>> The patch looks correct to me, but what compiler version and which kernel
>>>> tree is it that triggered the warning?
>>>>
>>>> Andrzej Hajda just modified the definition of IS_ERR_VALUE(), and the
>>>> changes are still under discussion, but I don't see that warning with
>>>> any of the versions.
>>>>
>>> I see it with gcc 5.1 and 5.2 (and W=1). I did not see / notice Andrzej's patch.
>>>
>>> I agree that fixing the problem in IS_ERR_VALUE() is preferrable.
>>>
>>>
>> Ah, W=1 explains it. We are still debating about the proper solution. Al Viro
>> pointed out that most users of IS_ERR_VALUE() shouldn't be using it at all,
>> so your patch is probably best here after all.
>>
> Yes, after looking into it some more I agree. Coccinelle should be able to handle
> most of the conversions automatically. I actually tried to write a script, just
> for the fun of it, but it misses some of the problem cases in patch mode.
> Maybe I get it working tonight.
>
> Guenter
>

Maybe it can be helpful. The script which classifies all IS_ERR_VALUE
usages as
correct, signed, incorrect and unknown (cocci was not able to detect type).
Adding patch mode should be quite simple.

// Options: --all-includes --include
include/uapi/linux/netfilter_ipv6/ip6_tables.h --include
include/uapi/linux/netfilter_ipv4/ip_tables.h --include
include/uapi/linux/netfilter_arp/arp_tables.h --include
include/uapi/linux/netfilter/x_tables.h --include include/linux/mm_types.h

virtual context
virtual report

@r@
typedef bool, u8, u16, u32, u64, s8, s16, s32, s64, __u64, dma_addr_t,
Elf32_Addr, Elf64_Addr;
{unsigned long, size_t} ev;
{short, int, long, s16, s32, ssize_t} ew;
{char, unsigned char, unsigned short, unsigned int, long long, unsigned
long long, bool, u8, u16, u32, u64, s64, __u64, dma_addr_t, Elf32_Addr,
Elf64_Addr} ei;
expression eu;
position p;
@@

IS_ERR_VALUE(\(ev \| ew \| ei \| eu \))@p

@script:python depends on report@
p << r.p = [];
ev << r.ev = "";
ew << r.ew = "";
ei << r.ei = "";
eu << r.eu = "";
@@

t = ""
if ev: t = "correct"
if ew: t = "signed"
if ei: t = "incorrect"
if eu: t = "unknown"


e = ev + ew + ei + eu;
if t:
    msg = "WARNING: %s argument type in IS_ERR_VALUE(%s)" % (t, e)
    coccilib.report.print_report(p[0], msg)

Re: [PATCH] tty/serial: digicolor: Fix bad usage of IS_ERR_VALUE

[Guenter Roeck]

On Thu, Feb 11, 2016 at 07:45:11AM +0100, Andrzej Hajda wrote:
> On 02/11/2016 04:38 AM, Guenter Roeck wrote:
> > On 02/10/2016 07:21 AM, Arnd Bergmann wrote:
> >> On Tuesday 09 February 2016 18:37:46 Guenter Roeck wrote:
> >>> On 02/09/2016 07:26 AM, Arnd Bergmann wrote:
> >>>> On Tuesday 09 February 2016 07:08:59 Guenter Roeck wrote:
> >>>>> IS_ERR_VALUE() assumes that its parameter is an unsigned long.
> >>>>> It can not be used to check if an unsigned int reflects an error.
> >>>>> Doing so can result in the following build warning.
> >>>>>
> >>>>> drivers/tty/serial/digicolor-usart.c: In function ‘digicolor_uart_probe’:
> >>>>> include/linux/err.h:21:38: warning:
> >>>>>           comparison is always false due to limited range of data type
> >>>>> drivers/tty/serial/digicolor-usart.c:485:6: note:
> >>>>>           in expansion of macro ‘IS_ERR_VALUE’
> >>>>>
> >>>>> If that warning is seen, an error return from platform_get_irq() is missed.
> >>>>>
> >>>>>
> >>>> The patch looks correct to me, but what compiler version and which kernel
> >>>> tree is it that triggered the warning?
> >>>>
> >>>> Andrzej Hajda just modified the definition of IS_ERR_VALUE(), and the
> >>>> changes are still under discussion, but I don't see that warning with
> >>>> any of the versions.
> >>>>
> >>> I see it with gcc 5.1 and 5.2 (and W=1). I did not see / notice Andrzej's patch.
> >>>
> >>> I agree that fixing the problem in IS_ERR_VALUE() is preferrable.
> >>>
> >>>
> >> Ah, W=1 explains it. We are still debating about the proper solution. Al Viro
> >> pointed out that most users of IS_ERR_VALUE() shouldn't be using it at all,
> >> so your patch is probably best here after all.
> >>
> > Yes, after looking into it some more I agree. Coccinelle should be able to handle
> > most of the conversions automatically. I actually tried to write a script, just
> > for the fun of it, but it misses some of the problem cases in patch mode.
> > Maybe I get it working tonight.
> >
> > Guenter
> >
> 
> Maybe it can be helpful. The script which classifies all IS_ERR_VALUE
> usages as
> correct, signed, incorrect and unknown (cocci was not able to detect type).
> Adding patch mode should be quite simple.
> 
> // Options: --all-includes --include
> include/uapi/linux/netfilter_ipv6/ip6_tables.h --include
> include/uapi/linux/netfilter_ipv4/ip_tables.h --include
> include/uapi/linux/netfilter_arp/arp_tables.h --include
> include/uapi/linux/netfilter/x_tables.h --include include/linux/mm_types.h
> 
> virtual context
> virtual report
> 
> @r@
> typedef bool, u8, u16, u32, u64, s8, s16, s32, s64, __u64, dma_addr_t,
> Elf32_Addr, Elf64_Addr;
> {unsigned long, size_t} ev;
> {short, int, long, s16, s32, ssize_t} ew;
> {char, unsigned char, unsigned short, unsigned int, long long, unsigned
> long long, bool, u8, u16, u32, u64, s64, __u64, dma_addr_t, Elf32_Addr,
> Elf64_Addr} ei;
> expression eu;
> position p;
> @@
> 
> IS_ERR_VALUE(\(ev \| ew \| ei \| eu \))@p
> 
> @script:python depends on report@
> p << r.p = [];
> ev << r.ev = "";
> ew << r.ew = "";
> ei << r.ei = "";
> eu << r.eu = "";

This doesn't work for me; it bails out at the assignments. If I remove
the assignments, it does not report anything.

Any idea what might be wrong ?

Thanks,
Guenter

> @@
> 
> t = ""
> if ev: t = "correct"
> if ew: t = "signed"
> if ei: t = "incorrect"
> if eu: t = "unknown"
> 
> 
> e = ev + ew + ei + eu;
> if t:
>     msg = "WARNING: %s argument type in IS_ERR_VALUE(%s)" % (t, e)
>     coccilib.report.print_report(p[0], msg)
> 
> 

Re: [PATCH] tty/serial: digicolor: Fix bad usage of IS_ERR_VALUE

[Andrzej Hajda]

On 02/11/2016 04:32 PM, Guenter Roeck wrote:
> On Thu, Feb 11, 2016 at 07:45:11AM +0100, Andrzej Hajda wrote:
>> On 02/11/2016 04:38 AM, Guenter Roeck wrote:
>>> On 02/10/2016 07:21 AM, Arnd Bergmann wrote:
>>>> On Tuesday 09 February 2016 18:37:46 Guenter Roeck wrote:
>>>>> On 02/09/2016 07:26 AM, Arnd Bergmann wrote:
>>>>>> On Tuesday 09 February 2016 07:08:59 Guenter Roeck wrote:
>>>>>>> IS_ERR_VALUE() assumes that its parameter is an unsigned long.
>>>>>>> It can not be used to check if an unsigned int reflects an error.
>>>>>>> Doing so can result in the following build warning.
>>>>>>>
>>>>>>> drivers/tty/serial/digicolor-usart.c: In function ‘digicolor_uart_probe’:
>>>>>>> include/linux/err.h:21:38: warning:
>>>>>>>           comparison is always false due to limited range of data type
>>>>>>> drivers/tty/serial/digicolor-usart.c:485:6: note:
>>>>>>>           in expansion of macro ‘IS_ERR_VALUE’
>>>>>>>
>>>>>>> If that warning is seen, an error return from platform_get_irq() is missed.
>>>>>>>
>>>>>>>
>>>>>> The patch looks correct to me, but what compiler version and which kernel
>>>>>> tree is it that triggered the warning?
>>>>>>
>>>>>> Andrzej Hajda just modified the definition of IS_ERR_VALUE(), and the
>>>>>> changes are still under discussion, but I don't see that warning with
>>>>>> any of the versions.
>>>>>>
>>>>> I see it with gcc 5.1 and 5.2 (and W=1). I did not see / notice Andrzej's patch.
>>>>>
>>>>> I agree that fixing the problem in IS_ERR_VALUE() is preferrable.
>>>>>
>>>>>
>>>> Ah, W=1 explains it. We are still debating about the proper solution. Al Viro
>>>> pointed out that most users of IS_ERR_VALUE() shouldn't be using it at all,
>>>> so your patch is probably best here after all.
>>>>
>>> Yes, after looking into it some more I agree. Coccinelle should be able to handle
>>> most of the conversions automatically. I actually tried to write a script, just
>>> for the fun of it, but it misses some of the problem cases in patch mode.
>>> Maybe I get it working tonight.
>>>
>>> Guenter
>>>
>> Maybe it can be helpful. The script which classifies all IS_ERR_VALUE
>> usages as
>> correct, signed, incorrect and unknown (cocci was not able to detect type).
>> Adding patch mode should be quite simple.
>>
>> // Options: --all-includes --include
>> include/uapi/linux/netfilter_ipv6/ip6_tables.h --include
>> include/uapi/linux/netfilter_ipv4/ip_tables.h --include
>> include/uapi/linux/netfilter_arp/arp_tables.h --include
>> include/uapi/linux/netfilter/x_tables.h --include include/linux/mm_types.h
>>
>> virtual context
>> virtual report
>>
>> @r@
>> typedef bool, u8, u16, u32, u64, s8, s16, s32, s64, __u64, dma_addr_t,
>> Elf32_Addr, Elf64_Addr;
>> {unsigned long, size_t} ev;
>> {short, int, long, s16, s32, ssize_t} ew;
>> {char, unsigned char, unsigned short, unsigned int, long long, unsigned
>> long long, bool, u8, u16, u32, u64, s64, __u64, dma_addr_t, Elf32_Addr,
>> Elf64_Addr} ei;
>> expression eu;
>> position p;
>> @@
>>
>> IS_ERR_VALUE(\(ev \| ew \| ei \| eu \))@p
>>
>> @script:python depends on report@
>> p << r.p = [];
>> ev << r.ev = "";
>> ew << r.ew = "";
>> ei << r.ei = "";
>> eu << r.eu = "";
> This doesn't work for me; it bails out at the assignments. If I remove
> the assignments, it does not report anything.
>
> Any idea what might be wrong ?

Old version of spatch. Default values are supported since 1.0.3.

Regards
Andrzej

Re: [PATCH] tty/serial: digicolor: Fix bad usage of IS_ERR_VALUE

[Russell King - ARM Linux]

On Tue, Feb 09, 2016 at 06:37:46PM -0800, Guenter Roeck wrote:
> On 02/09/2016 07:26 AM, Arnd Bergmann wrote:
> >On Tuesday 09 February 2016 07:08:59 Guenter Roeck wrote:
> >>IS_ERR_VALUE() assumes that its parameter is an unsigned long.
> >>It can not be used to check if an unsigned int reflects an error.
> >>Doing so can result in the following build warning.
> >>
> >>drivers/tty/serial/digicolor-usart.c: In function ‘digicolor_uart_probe’:
> >>include/linux/err.h:21:38: warning:
> >>         comparison is always false due to limited range of data type
> >>drivers/tty/serial/digicolor-usart.c:485:6: note:
> >>         in expansion of macro ‘IS_ERR_VALUE’
> >>
> >>If that warning is seen, an error return from platform_get_irq() is missed.
> >>
> >>
> >
> >The patch looks correct to me, but what compiler version and which kernel
> >tree is it that triggered the warning?
> >
> >Andrzej Hajda just modified the definition of IS_ERR_VALUE(), and the
> >changes are still under discussion, but I don't see that warning with
> >any of the versions.
> >
> I see it with gcc 5.1 and 5.2 (and W=1). I did not see / notice Andrzej's patch.
> 
> I agree that fixing the problem in IS_ERR_VALUE() is preferrable.

I disagree.  What happens if (eg) you decide to do this:

	u8 irq;

	irq = platform_get_irq(...);
	if (IS_ERR_VALUE(irq))
		...

is that the fault of IS_ERR_VALUE() that it will never be true?  No, it's
a programming error in the caller, because the caller is using the wrong
type here - in fact, you can't do anything in IS_ERR_VALUE() to correct
that.

The same is true if you assign an error value to an unsigned int: the
problem is in the caller, not in IS_ERR_VALUE().

What would be preferable is if there was some way IS_ERR_VALUE() could
detect if it's used on something that isn't at least a short, and is
signed, but I suspect coccinelle can do that much better than trying to
work out some way to get the C compiler to check that.

-- 
RMK's Patch system: http://www.arm.linux.org.uk/developer/patches/
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.

Re: [PATCH] tty/serial: digicolor: Fix bad usage of IS_ERR_VALUE

[Guenter Roeck]

On Thu, Feb 11, 2016 at 10:46:50AM +0000, Russell King - ARM Linux wrote:
> On Tue, Feb 09, 2016 at 06:37:46PM -0800, Guenter Roeck wrote:
> > On 02/09/2016 07:26 AM, Arnd Bergmann wrote:
> > >On Tuesday 09 February 2016 07:08:59 Guenter Roeck wrote:
> > >>IS_ERR_VALUE() assumes that its parameter is an unsigned long.
> > >>It can not be used to check if an unsigned int reflects an error.
> > >>Doing so can result in the following build warning.
> > >>
> > >>drivers/tty/serial/digicolor-usart.c: In function ‘digicolor_uart_probe’:
> > >>include/linux/err.h:21:38: warning:
> > >>         comparison is always false due to limited range of data type
> > >>drivers/tty/serial/digicolor-usart.c:485:6: note:
> > >>         in expansion of macro ‘IS_ERR_VALUE’
> > >>
> > >>If that warning is seen, an error return from platform_get_irq() is missed.
> > >>
> > >>
> > >
> > >The patch looks correct to me, but what compiler version and which kernel
> > >tree is it that triggered the warning?
> > >
> > >Andrzej Hajda just modified the definition of IS_ERR_VALUE(), and the
> > >changes are still under discussion, but I don't see that warning with
> > >any of the versions.
> > >
> > I see it with gcc 5.1 and 5.2 (and W=1). I did not see / notice Andrzej's patch.
> > 
> > I agree that fixing the problem in IS_ERR_VALUE() is preferrable.
> 
> I disagree.  What happens if (eg) you decide to do this:
> 
> 	u8 irq;
> 
> 	irq = platform_get_irq(...);
> 	if (IS_ERR_VALUE(irq))
> 		...
> 
> is that the fault of IS_ERR_VALUE() that it will never be true?  No, it's
> a programming error in the caller, because the caller is using the wrong
> type here - in fact, you can't do anything in IS_ERR_VALUE() to correct
> that.
> 
Yes, I think we all reached that conclusion by now.

Thanks,
Guenter

Re: [PATCH] tty/serial: digicolor: Fix bad usage of IS_ERR_VALUE

[Baruch Siach]

Hi Guenter,

On Tue, Feb 09, 2016 at 07:08:59AM -0800, Guenter Roeck wrote:
> IS_ERR_VALUE() assumes that its parameter is an unsigned long.
> It can not be used to check if an unsigned int reflects an error.
> Doing so can result in the following build warning.
> 
> drivers/tty/serial/digicolor-usart.c: In function ‘digicolor_uart_probe’:
> include/linux/err.h:21:38: warning:
> 	comparison is always false due to limited range of data type
> drivers/tty/serial/digicolor-usart.c:485:6: note:
> 	in expansion of macro ‘IS_ERR_VALUE’
> 
> If that warning is seen, an error return from platform_get_irq() is missed.
> 
> Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Acked-by: Baruch Siach <baruch@tkos.co.il>

Thanks,
baruch

> ---
>  drivers/tty/serial/digicolor-usart.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/tty/serial/digicolor-usart.c b/drivers/tty/serial/digicolor-usart.c
> index a80cdad114f3..02ad6953b167 100644
> --- a/drivers/tty/serial/digicolor-usart.c
> +++ b/drivers/tty/serial/digicolor-usart.c
> @@ -453,7 +453,7 @@ static struct uart_driver digicolor_uart = {
>  static int digicolor_uart_probe(struct platform_device *pdev)
>  {
>  	struct device_node *np = pdev->dev.of_node;
> -	int ret, index;
> +	int irq, ret, index;
>  	struct digicolor_port *dp;
>  	struct resource *res;
>  	struct clk *uart_clk;
> @@ -481,9 +481,10 @@ static int digicolor_uart_probe(struct platform_device *pdev)
>  	if (IS_ERR(dp->port.membase))
>  		return PTR_ERR(dp->port.membase);
>  
> -	dp->port.irq = platform_get_irq(pdev, 0);
> -	if (IS_ERR_VALUE(dp->port.irq))
> -		return dp->port.irq;
> +	irq = platform_get_irq(pdev, 0);
> +	if (irq < 0)
> +		return irq;
> +	dp->port.irq = irq;
>  
>  	dp->port.iotype = UPIO_MEM;
>  	dp->port.uartclk = clk_get_rate(uart_clk);

-- 
     http://baruch.siach.name/blog/                  ~. .~   Tk Open Systems
=}------------------------------------------------ooO--U--Ooo------------{=
   - baruch@tkos.co.il - tel: +972.2.679.5364, http://www.tkos.co.il -