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SubjectRe: [PATCH] [v3] y2038: introduce struct __kernel_old_timeval
On Fri, Mar 16, 2018 at 1:02 AM, Thomas Gleixner <tglx@linutronix.de> wrote:
> On Thu, 15 Mar 2018, Arnd Bergmann wrote:
>> + * legacy timeval structure, only embedded in structures that
>> + * traditionally used 'timeval' to pass time intervals (not absolute
>> + * times). Do not add new users. If user space fails to compile
>> + * here, this is probably because it is not y2038 safe and needs to
>> + * be changed to use another interface.
>> + */
>> +struct __kernel_old_timeval {
>> + __kernel_long_t tv_sec;
>> + __kernel_long_t tv_usec;
>> +};
>> +
>> +/*
>> * The IDs of the various system clocks (for POSIX.1b interval timers):
>> */
>> #define CLOCK_REALTIME 0
>> diff --git a/kernel/time/time.c b/kernel/time/time.c
>> index 5db8f15ec056..6fa99213fc72 100644
>> --- a/kernel/time/time.c
>> +++ b/kernel/time/time.c
>> @@ -486,6 +486,18 @@ struct timeval ns_to_timeval(const s64 nsec)
>> }
>> EXPORT_SYMBOL(ns_to_timeval);
>>
>> +struct __kernel_old_timeval ns_to_kernel_old_timeval(const s64 nsec)
>> +{
>> + struct timespec64 ts = ns_to_timespec64(nsec);
>> + struct __kernel_old_timeval tv;
>> +
>> + tv.tv_sec = ts.tv_sec;
>
> We might think about adding some debug aid here which yells when ts.tv_sec
> is > than the cutoff.
>
> Hmm?

We discussed those before (a long time ago) and couldn't really
reach consensus. If we do that, I'd like to have it done consistently
across the kernel, and in a separate patch series.

In particular, we need to decide on a policy for how to handle
it depending on the caller, e.g. do we want to have a way to
WARN_ONCE() for any process calling an unsafe function even
if it doesn't overflow, should we try to return an error to a syscall
when it does overflow, should the behavior be configurable etc.

Arnd

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