igb_uio: fix build on Linux 5.3 for implicit fall through

  build error:
.../dpdk/build/build/kernel/linux/igb_uio/igb_uio.c:
   In function ‘igbuio_pci_enable_interrupts’:
   .../dpdk/build/build/kernel/linux/igb_uio/igb_uio.c:230:6:
   error: this statement may fall through
   [-Werror=implicit-fallthrough=]
  230 |   if (pci_alloc_irq_vectors(udev->pdev, 1, 1, ....
.../dpdk/build/build/kernel/linux/igb_uio/igb_uio.c:240:2:
   note: here
  240 |  case RTE_INTR_MODE_MSI:
      |  ^~~~

The build error is caused by Linux kernel commit in 5.3 that enables the
"-Wimplicit-fallthrough=3" gcc flag.
Commit a035d552a93b ("Makefile: Globally enable fall-through warning")

To fix the error, either a gcc attribute can be provided [1] or a code
comment with some defined syntax need to be provided [2], since there is
already comments, updated them slightly to match the required syntax to
fix the build error.

[1]
"__attribute__ ((fallthrough));"

[2]
[ \t.!]*([Ee]lse,? |[Ii]ntentional(ly)? )?
fall(s | |-)?thr(ough|u)[ \t.!]*(-[^\n\r]*)?

Cc: stable@dpdk.org

Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com>
---
 kernel/linux/igb_uio/igb_uio.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
  

29/07/2019 14:32, Ferruh Yigit:
> build error:
> .../dpdk/build/build/kernel/linux/igb_uio/igb_uio.c:
>    In function ‘igbuio_pci_enable_interrupts’:
>    .../dpdk/build/build/kernel/linux/igb_uio/igb_uio.c:230:6:
>    error: this statement may fall through
>    [-Werror=implicit-fallthrough=]
>   230 |   if (pci_alloc_irq_vectors(udev->pdev, 1, 1, ....
> .../dpdk/build/build/kernel/linux/igb_uio/igb_uio.c:240:2:
>    note: here
>   240 |  case RTE_INTR_MODE_MSI:
>       |  ^~~~
> 
> The build error is caused by Linux kernel commit in 5.3 that enables the
> "-Wimplicit-fallthrough=3" gcc flag.
> Commit a035d552a93b ("Makefile: Globally enable fall-through warning")
> 
> To fix the error, either a gcc attribute can be provided [1] or a code
> comment with some defined syntax need to be provided [2], since there is
> already comments, updated them slightly to match the required syntax to
> fix the build error.
> 
> [1]
> "__attribute__ ((fallthrough));"
> 
> [2]
> [ \t.!]*([Ee]lse,? |[Ii]ntentional(ly)? )?
> fall(s | |-)?thr(ough|u)[ \t.!]*(-[^\n\r]*)?
> 
> Cc: stable@dpdk.org
> 
> Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com>

Applied, thanks
  

On Mon, 2019-07-29 at 13:32 +0100, Ferruh Yigit wrote:
> build error:
> .../dpdk/build/build/kernel/linux/igb_uio/igb_uio.c:
>    In function ‘igbuio_pci_enable_interrupts’:
>    .../dpdk/build/build/kernel/linux/igb_uio/igb_uio.c:230:6:
>    error: this statement may fall through
>    [-Werror=implicit-fallthrough=]
>   230 |   if (pci_alloc_irq_vectors(udev->pdev, 1, 1, ....
> .../dpdk/build/build/kernel/linux/igb_uio/igb_uio.c:240:2:
>    note: here
>   240 |  case RTE_INTR_MODE_MSI:
>       |  ^~~~
> 
> The build error is caused by Linux kernel commit in 5.3 that enables
> the
> "-Wimplicit-fallthrough=3" gcc flag.
> Commit a035d552a93b ("Makefile: Globally enable fall-through
> warning")
> 
> To fix the error, either a gcc attribute can be provided [1] or a
> code
> comment with some defined syntax need to be provided [2], since there
> is
> already comments, updated them slightly to match the required syntax
> to
> fix the build error.
> 
> [1]
> "__attribute__ ((fallthrough));"
> 
> [2]
> [ \t.!]*([Ee]lse,? |[Ii]ntentional(ly)? )?
> fall(s | |-)?thr(ough|u)[ \t.!]*(-[^\n\r]*)?
> 
> Cc: 
> stable@dpdk.org
> 
> 
> Signed-off-by: Ferruh Yigit <
> ferruh.yigit@intel.com
> >
> ---
>  kernel/linux/igb_uio/igb_uio.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)

Ferruh I'm including this in 17.11.7 since it fixes the build on a
number of new distros and it seems simple enough as it just updates the
comment for the compiler's benefit.

Let me know if there are any objections.
  

On 9/24/2019 7:25 PM, Luca Boccassi wrote:
> On Mon, 2019-07-29 at 13:32 +0100, Ferruh Yigit wrote:
>> build error:
>> .../dpdk/build/build/kernel/linux/igb_uio/igb_uio.c:
>>    In function ‘igbuio_pci_enable_interrupts’:
>>    .../dpdk/build/build/kernel/linux/igb_uio/igb_uio.c:230:6:
>>    error: this statement may fall through
>>    [-Werror=implicit-fallthrough=]
>>   230 |   if (pci_alloc_irq_vectors(udev->pdev, 1, 1, ....
>> .../dpdk/build/build/kernel/linux/igb_uio/igb_uio.c:240:2:
>>    note: here
>>   240 |  case RTE_INTR_MODE_MSI:
>>       |  ^~~~
>>
>> The build error is caused by Linux kernel commit in 5.3 that enables
>> the
>> "-Wimplicit-fallthrough=3" gcc flag.
>> Commit a035d552a93b ("Makefile: Globally enable fall-through
>> warning")
>>
>> To fix the error, either a gcc attribute can be provided [1] or a
>> code
>> comment with some defined syntax need to be provided [2], since there
>> is
>> already comments, updated them slightly to match the required syntax
>> to
>> fix the build error.
>>
>> [1]
>> "__attribute__ ((fallthrough));"
>>
>> [2]
>> [ \t.!]*([Ee]lse,? |[Ii]ntentional(ly)? )?
>> fall(s | |-)?thr(ough|u)[ \t.!]*(-[^\n\r]*)?
>>
>> Cc: 
>> stable@dpdk.org
>>
>>
>> Signed-off-by: Ferruh Yigit <
>> ferruh.yigit@intel.com
>>>
>> ---
>>  kernel/linux/igb_uio/igb_uio.c | 6 +++---
>>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> Ferruh I'm including this in 17.11.7 since it fixes the build on a
> number of new distros and it seems simple enough as it just updates the
> comment for the compiler's benefit.
> 
> Let me know if there are any objections.
> 

+1 to include it, as you said it is simple, thanks.