Messages in this thread | | | Date | Thu, 01 Sep 2005 23:37:34 +0200 | From | Eric Dumazet <> | Subject | Re: [RFC][PATCH] Use proper casting with signed timespec.tv_nsec values |
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john stultz a écrit : > All, > I recently ran into a bug with an older kernel where xtime's tv_nsec > field had accumulated more then 2 seconds worth of time. The timespec's > tv_nsec is a signed long, however gettimeofday() treats it as an > unsigned long. Thus when the failure occured, very strange and difficult > to debug time problems occurred. > > The main cause of the problem I was seeing is already fixed in mainline, > however just to be safe, I figured the following patch would be wise. > > I only audited i386 and x86_64, however other arches probably could have > similar signed problems as well. > > Please let me know if you have any further comments or feedback.
What happens on i386 when/if more than 4 seconds accumulate ? That should happens too. Maybe the real fix is elsewhere ?
> > thanks > -john > > linux-2.6.13_signed-tv_nsec_A0.patch > ==================================== > --- a/kernel/timer.c > +++ b/kernel/timer.c > @@ -824,7 +824,7 @@ static void update_wall_time(unsigned lo > do { > ticks--; > update_wall_time_one_tick(); > - if (xtime.tv_nsec >= 1000000000) { > + if ((unsigned long)xtime.tv_nsec >= 1000000000) { > xtime.tv_nsec -= 1000000000; > xtime.tv_sec++; > second_overflow(); >
maybe here a :
while ((unsigned long)xtime.tv_nsec >= 1000000000) { xtime.tv_nsec -= 1000000000; xtime.tv_sec++; second_overflow(); ... }
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