Thomas, does this make sense now, with the new description? On Fri, Apr 18, 2014 at 05:23:11PM +0200, Jiri Bohac wrote: > On architectures with sizeof(int) < sizeof (long), the > computation of mask inside apply_slack() can be undefined if the > computed bit is > 32. > > E.g. with: expires = 0xffffe6f5 and slack = 25, we get: > > expires_limit = 0x20000000e > bit = 33 > mask = (1 << 33) - 1 /* undefined */ > > On x86, mask becomes 1 and and the slack is not applied properly. > On s390, mask is -1, expires is set to 0 and the timer fires immediately. > > Signed-off-by: Jiri Bohac <[email protected]> > Suggested-by: Deborah Townsend <[email protected]> > > diff --git a/kernel/timer.c b/kernel/timer.c > index 87bd529..4c36c91 100644 > --- a/kernel/timer.c > +++ b/kernel/timer.c > @@ -838,7 +838,7 @@ unsigned long apply_slack(struct timer_list *timer, > unsigned long expires) > > bit = find_last_bit(&mask, BITS_PER_LONG); > > - mask = (1 << bit) - 1; > + mask = (1LL << bit) - 1; > > expires_limit = expires_limit & ~(mask); >
Thanks, -- Jiri Bohac <[email protected]> SUSE Labs, SUSE CZ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
