* Bug in testsuite/gdb.base/tls.c
@ 2003-07-29 20:07 Michael Elizabeth Chastain
2003-07-29 20:56 ` Elena Zannoni
0 siblings, 1 reply; 2+ messages in thread
From: Michael Elizabeth Chastain @ 2003-07-29 20:07 UTC (permalink / raw)
To: ezannoni; +Cc: gdb
I'm seeing a lot of test suite hangs with the new tls.c.
I tracked it down to this code:
for( i = 0; i < N_THREADS; i++ )
{
do
{
errno = 0;
if (sem_wait (&tell_main) == -1)
{
if (errno != EINTR)
{
...
return;
}
...
}
}
while (errno == EINTR);
}
It turns out that errno can be EINTR even when the return value is 0!
That screws up the loop counter.
This happened with Red Hat Linux 8, glibc 2.2.93-5-rh. It is sensitive
to the placement of breakpoints, which is not surprising.
I think it's normal Unix semantics that when the return value is zero,
errno has no meaning.
I'll code up a patch for tls.c, on those lines.
Michael C
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: Bug in testsuite/gdb.base/tls.c
2003-07-29 20:07 Bug in testsuite/gdb.base/tls.c Michael Elizabeth Chastain
@ 2003-07-29 20:56 ` Elena Zannoni
0 siblings, 0 replies; 2+ messages in thread
From: Elena Zannoni @ 2003-07-29 20:56 UTC (permalink / raw)
To: Michael Elizabeth Chastain; +Cc: ezannoni, gdb
Michael Elizabeth Chastain writes:
> I'm seeing a lot of test suite hangs with the new tls.c.
> I tracked it down to this code:
>
> for( i = 0; i < N_THREADS; i++ )
> {
> do
> {
> errno = 0;
>
> if (sem_wait (&tell_main) == -1)
> {
> if (errno != EINTR)
> {
> ...
> return;
> }
> ...
> }
> }
> while (errno == EINTR);
> }
>
> It turns out that errno can be EINTR even when the return value is 0!
> That screws up the loop counter.
Whoops, never seen this one happening on my systems, just (bad) luck I guess.
>
> This happened with Red Hat Linux 8, glibc 2.2.93-5-rh. It is sensitive
> to the placement of breakpoints, which is not surprising.
>
> I think it's normal Unix semantics that when the return value is zero,
> errno has no meaning.
Yes, true.
"All semaphore functions introduced by POSIX.1b use the old error
reporting mechanism. These functions return 0 on success and -1 on
error, with errno set to the appropriate error"
Note how it carefully avoids mentioning what happens to errno in case
of success.
>
> I'll code up a patch for tls.c, on those lines.
>
thanks
elena
> Michael C
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