[dpdk-dev] [PATCH] vhost: fix build issue caused by unchecked returned values

[Maxime Coquelin]

On 03/30/2018 05:21 PM, Ferruh Yigit wrote:
> On 3/30/2018 4:18 PM, Andrew Rybchenko wrote:
>> On 03/30/2018 06:16 PM, Maxime Coquelin wrote:
>>> This patch fixes below build issue seen with some compilers
>>> or build options:
>>>
>>> lib/librte_vhost/fd_man.c: In function ‘fdset_pipe_read_cb’:
>>> lib/librte_vhost/fd_man.c:284:2: error: ignoring return value of ‘read’, declared with attribute warn_unused_result [-Werror=unused-result]
>>>    read(readfd, charbuf, sizeof(charbuf));
>>>    ^
>>> lib/librte_vhost/fd_man.c: In function ‘fdset_pipe_notify’:
>>> lib/librte_vhost/fd_man.c:324:2: error: ignoring return value of ‘write’, declared with attribute warn_unused_result [-Werror=unused-result]
>>>    write(fdset->u.writefd, "1", 1);
>>>    ^
>>>
>>> Reported-by: Andrew Rybchenko <arybchenko at solarflare.com>
>>> Signed-off-by: Tonghao Zhang <xiangxia.m.yue at gmail.com>
>>> Signed-off-by: Maxime Coquelin <maxime.coquelin at redhat.com>
>>> ---
>>>   lib/librte_vhost/fd_man.c | 17 +++++++++++++++--
>>>   1 file changed, 15 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/lib/librte_vhost/fd_man.c b/lib/librte_vhost/fd_man.c
>>> index ca1ba2622..1f9e22f96 100644
>>> --- a/lib/librte_vhost/fd_man.c
>>> +++ b/lib/librte_vhost/fd_man.c
>>> @@ -281,7 +281,13 @@ fdset_pipe_read_cb(int readfd, void *dat __rte_unused,
>>>   		   int *remove __rte_unused)
>>>   {
>>>   	char charbuf[16];
>>> -	read(readfd, charbuf, sizeof(charbuf));
>>> +	int r = read(readfd, charbuf, sizeof(charbuf));
>>> +	/*
>>> +	 * Just an optimization, we don't care if read() failed
>>> +	 * so ignore explicitly its return value to make the
>>> +	 * compiler happy
>>> +	 */
>>> +	RTE_SET_USED(r);
>>>   }
>>>   
>>>   void
>>> @@ -321,5 +327,12 @@ fdset_pipe_init(struct fdset *fdset)
>>>   void
>>>   fdset_pipe_notify(struct fdset *fdset)
>>>   {
>>> -	write(fdset->u.writefd, "1", 1);
>>> +	int r = write(fdset->u.writefd, "1", 1);
>>> +	/*
>>> +	 * Just an optimization, we don't care if read() failed
>>
>> read() -> write()
> 
> I can fix while applying.

Thanks!

> 
>>
>>> +	 * so ignore explicitly its return value to make the
>>> +	 * compiler happy
>>> +	 */
>>> +	RTE_SET_USED(r);
>>> +
>>>   }
>>
>