Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
clocksource: Don't use non-continuous clocksources as watchdog
Using a non-continuous aka untrusted clocksource as a watchdog for another
untrusted clocksource is equivalent to putting the fox in charge of the
henhouse.
That's especially true with the jiffies clocksource which depends on
interrupt delivery based on a periodic timer. Neither the frequency of that
timer is trustworthy nor the kernel's ability to react on it in a timely
manner and rearm it if it is not self rearming.
Just don't bother to deal with this. It's not worth the trouble and only
relevant to museum piece hardware.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/20260123231521.858743259@kernel.org
+7
+7
kernel/time/clocksource.c
+7
kernel/time/clocksource.c
···
651
651
if (cs->flags & CLOCK_SOURCE_MUST_VERIFY)
652
652
continue;
653
653
654
+
/*
655
+
* If it's not continuous, don't put the fox in charge of
656
+
* the henhouse.
657
+
*/
658
+
if (!(cs->flags & CLOCK_SOURCE_IS_CONTINUOUS))
659
+
continue;
660
+
654
661
/* Skip current if we were requested for a fallback. */
655
662
if (fallback && cs == old_wd)
656
663
continue;