RE: negative timeout can be set up by setsockopt system call

[Ram Gupta <ram.gupta5@gmail.com>]

On 11/7/05, Ram Gupta <ram.gupta5@gmail.com> wrote:
 > On 11/4/05, Nish Aravamudan <nish.aravamudan@gmail.com>
 >  >
 >  > In Ram's specific case, I think, the call path is sys_setsockopt() ->
 >  > sock_setsockopt() -> sock_set_timeout, which has a definition of:
 >  >
 >  > static int sock_set_timeout(long *timeo_p, char __user *optval, int
 > optlen)
 >
 >  >> Exactly right.

Ok.

 >  > Ram, what is the expected behavior of negative values in the timeval?
 >  > And what are you seeing happen right now?
 >  >
 >  > As of 2.6.14, looks like we convert any non-zero values into jiffies
 >  > and store them in sk->sk_{rcv,snd}timeo...
 >  >
 >  I don't see any problem from the kernel side but the application
 > times out immediately causing certain failures as the schedule_timeout
 > returns immediately in case of negative values. Shouldn't there be a
 > check for negative values and return error to the application so that
 > it can handle it.

I mean more along the lines of what does a man-page say the kernel
should be doing if you request a negative timeout? More explicitly,
what made you think negative timeouts should have a specific effect?

 >> The man page is silent about the timeout behaviour in case of its 
being negative.  I believe that negative timeout is a mistake on behalf 
of an application and hence should be treated as such (i.e should be 
notified accordingly)

When you say schedule_timeout() returns immediately, I assume your
logs are filling up with "schedule_timeout: wrong timeout ..." ? (You
may need to bump your loglevel). If not, then schedule_timeout() isn't
getting a negative value.

 >> Yes  I am getting the "schedule_timeout: wrong timeout ..." 
messages so I am sure the timeout has negative value.


Thanks,
Nish

regards
Ram Gupta