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Date: Tue, 11 Feb 2020 12:16:18 +0300
From: Alexander Scherbatiy <alexander.scherbatiy@...l-sw.com>
To: musl@...ts.openwall.com, Rich Felker <dalias@...c.org>
Subject: Re: No such process return value in pthread_getcpuclockid

On 10.02.2020 23:14, Rich Felker wrote:

> The specification of ESRCH for pthread interfaces was a bug, because a
> "shall fail" or even "may fail" condition makes no sense with a
> behavior that's explicitly undefined (in which case the implementation
> is allowed to do anything at all). This was clarified in POSIX 2008 as
> a result of Austin Group interpretation 142:
>
> https://collaboration.opengroup.org/austin/interps/documents/14366/AI-142.txt

  Thank you. It sounds right that If an application attempts to use a 
thread ID whose lifetime has ended, the behavior is undefined.


  I see that "POSIX 2008 as a result of Austin Group interpretation 142" 
has strange comment about pthread_getcpuclockid() function:

   "The same argument applies to the ESRCH errors for pthread_detach(),  
pthread_getschedparam(), pthread_setschedparam() and  
pthread_setschedprio().

   (It does not apply to pthread_getcpuclockid() since the function  
could just always return a fixed clock ID without needing to  examine 
the thread ID.)"

   What does it mean that pthread_getcpuclockid() does not need to 
examine the thread ID? As I see from the musl pthread_getcpuclockid() 
implementation it really uses the thread ID:

https://git.musl-libc.org/cgit/musl/tree/src/thread/pthread_getcpuclockid.c


   Thanks,

   Alexander.

>
> Unfortunately the Linux man pages have not corrected this.
>
> Rich

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