Re: pthread_cond_signal/broadcast: necessary to hold mutex?

On 3/25/26 4:40 PM, Robert Elz wrote:
>      Date:        Tue, 24 Mar 2026 20:37:13 -0400
>      From:        Greg Troxel <[email protected]>
>      Message-ID:  <[email protected]>
> 
>    | J�rg Sonnenberger <[email protected]> writes:
> 
>    | > Neither signal nor broadcast unlocks the mutex. Only cv_wait may
>    | > release the mutex before blocking.
>    |
>    | Makes sense but I can't find that in the POSIX text.
> 
> That would be:
> 
> 	The pthread_cond_broadcast() or pthread_cond_signal() functions
> 	may be called by a thread whether or not it currently owns the mutex
> 
> If those functions don't know whether or not the caller owns the mutex,
> clearly they can't go manipulating the thing, if the current thread doesn't
> own it, some other might have it locked, and not appreciate it suddenly
> becoming unlocked, for no apparent reason to it.

No, that doesn't justify that they don't unlock the mutex. But at the 
same time, unlike e.g. pthread_cond_wait, there is nothing given them 
the liberty to release the mutex either.

Joreg