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

[Ferruh Yigit]

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.

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