times(2) misbehaviour

Denys Vlasenko vda.linux at googlemail.com
Thu Apr 24 19:20:02 UTC 2008

On Thursday 24 April 2008 14:39, Will Newton wrote:
> Hi,
> It looks to me as if times(2) is broken with Linux 2.6 on a 32bit
> arch. Can anyone confirm if this analysis is correct?
> Looking at sys_times in the 2.6 kernel it returns like this:
>         return (long) jiffies_64_to_clock_t(get_jiffies_64());
> On a 32bit arch that takes the bottom 32bits of a 64bit value.
> The system call wrappers in uClibc then examine the return code of the
> system call and if it is greater than a certain unsigned value assumes
> it is an errno value (negative). e.g. for arm:
> #define INTERNAL_SYSCALL_ERROR_P(val, err) \
>   ((unsigned int) (val) >= 0xfffff001u)
> This is effectively testing the bottom 32bits of jiffies_64 against
> the largest known errno value which occasionally will be true even
> when no error has been returned.

Just delete the check for error.

My take is that this syscall should be considered
as "never returning errors".

The only programs which will see the difference are buggy already
since they pass invalid pointer to kernel.
There is not much sence in truing to be 100.00% correct
with such programs (won't help them anyway) while
creating problems for non-buggy ones.

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