Re: pthread_cond_signal/broadcast: necessary to hold mutex?

[Greg Troxel <gdt%lexort.com@localhost>]

Thomas Klausner <wiz%netbsd.org@localhost> writes:

> On Mon, Mar 23, 2026 at 05:19:18PM +0100, Greg Troxel wrote:
>> Also, our man page talks about "changing the mutex" associated with the
>> pthread_cond_t, but as I read POSIX there is no rule that you can't have
>> N threads waiting on the same condvar each with a different mutex.  The
>> mutex is just about the wait caller, holding it on entry and getting it
>> back later, with it released in between.
>> 
>> It would be interesting to see what the code does; this could just be a
>> doc issue.
>
> How I understand the code is that a mutex is saved in the cond
> structure, and there is only place for one - so I think the
> requirement is actually true in NetBSD.

That is a separate bug then, as I understand POSIX.