Re: sys_times() return value

From: Russell King
Date: Fri Jul 29 2005 - 05:39:12 EST

On Sat, Jul 23, 2005 at 03:35:31PM +1000, Andrew Morton wrote:
> Russell King <rmk+lkml@xxxxxxxxxxxxxxxx> wrote:
> > ARM folk have recently pointed out a problem with sys_times().
> > When the kernel boots, we set jiffies to -5 minutes. This causes
> > sys_times() to return a negative number, which increments through
> > zero.
> >
> > However, some negative numbers are used to return error codes.
> > Hence, there's a period of time when sys_times() returns values
> > which are indistinguishable from error codes shortly after boot.
> What a strange system call.
> > This probably only affects 32-bit architectures. However, one
> > wonders whether sys_times() needs force_successful_syscall_return().
> I'd say so, yes. But lots of architectures seem to have a no-op there.

As I mentioned below, these other architectures need glibc to be fixed.

> > Also, it appears that glibc does indeed interpret the return value
> > from sys_times in the way I describe above on at least ARM and x86.
> > Other architectures may be similarly affected. Hopefully the ARM
> > glibc folk will raise a cross-architecture bug in glibc for this.

Russell King
Linux kernel 2.6 ARM Linux -
maintainer of: 2.6 Serial core
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