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Re: gdb and multi-threaded (NPTL) programs
- From: Eric Desjardins <eric dot desjardins at autodesk dot com>
- To: Andreas Schwab <schwab at suse dot de>
- Cc: John Fodor <john_fodor at mac dot com>, gdb at sourceware dot org
- Date: Fri, 24 Mar 2006 15:27:36 -0500
- Subject: Re: gdb and multi-threaded (NPTL) programs
- References: <44244F1F.6030108@mac.com> <je4q1n4mmp.fsf@sykes.suse.de>
Hi,
Well I was suprised at first when I discover that. On my RHEL 4.0
machine, the man page is not very EINTR aware. Maybe it is a man page
bug?
Eric
RETURN VALUE
The sem_wait and sem_getvalue functions always return 0. All
other semaphore functions return 0 on success and -1
on error, in addition to writing an error code in errno.
ERRORS
The sem_init function sets errno to the following codes on error:
EINVAL value exceeds the maximal counter value
SEM_VALUE_MAX
ENOSYS pshared is not zero
The sem_trywait function sets errno to the following error code
on error:
EAGAIN the semaphore count is currently 0
The sem_post function sets errno to the following error code on
error:
ERANGE after incrementation, the semaphore value would
exceed SEM_VALUE_MAX (the semaphore count is left
unchanged in this case)
The sem_destroy function sets errno to the following error code
on error:
EBUSY some threads are currently blocked waiting on the
semaphore.
AUTHOR
Xavier Leroy <Xavier.Leroy@inria.fr>
Le vendredi 24 mars 2006 Ã 21:24 +0100, Andreas Schwab a Ãcrit :
> John Fodor <john_fodor@mac.com> writes:
>
> > Hmmm... so people who use POSIX threads have to put every syscall into a
> > loop, ignoring EINTR?
>
> Every library call that is allowed to return with EINTR must be handled
> appropriately. sem_wait is specified as being able to return with EINTR.
> If your program can't handle that it has a bug.
>
> Andreas.