kern/81951: [patch] linux emulation: getpriority() returns incorrect value

Andriy Gapon avg at icyb.net.ua
Thu Jun 9 04:30:18 GMT 2005


The following reply was made to PR kern/81951; it has been noted by GNATS.

From: Andriy Gapon <avg at icyb.net.ua>
To: Maxim.Sobolev at portaone.com
Cc: bug-followup at FreeBSD.org
Subject: Re: kern/81951: [patch] linux emulation: getpriority() returns incorrect
 value
Date: Thu, 09 Jun 2005 07:22:32 +0300

 on 08.06.2005 23:49 Maxim Sobolev said the following:
 > Committed, thanks!
 > 
 > I wonder if the setpriority(2) needs the same cure. Please clarify and
 > let me know. I'll keep the PR open till your reply.
 > 
 
 Maxim,
 
 setpriority(2) is not affected, the reason for this assymetry is in
 Linux's convention for system calls - they return both result and errno
 in the same register, positive values are reserved for results of
 successful calls and negative are reserved for -errno for failed calls.
 Thus they can not return negative priority values in getpriority(2) and
 have to shift it to positive range. There is no problem, of course, with
 passing negative values from userland to kernel.
 
 Thank you for the commit!
 
 -- 
 Andriy Gapon


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