timecounter: Merge FreeBSD change r303387

Prevent parallel tc_windup() calls, both parallel top-level calls from setclock() and from simultaneous top-level and interrupt. For this, tc_windup() is protected with a tc_setclock_mtx spinlock, in the try mode when called from hardclock interrupt. If spinlock cannot be obtained without spinning from the interrupt context, this means that top-level executes tc_windup() on other core and our try may be avoided.

The boottimebin and boottime variables should be adjusted from
tc_windup().  To be correct, they must be part of the timehands and
read using lockless protocol.  Remove the globals and reimplement the
getboottime(9)/getboottimebin(9) KPI using the timehands read
protocol.

Tested by:	pho (as part of the whole patch)
Reviewed by:	jhb (same)
Discussed wit:	bde
Sponsored by:	The FreeBSD Foundation
MFC after:	1 month
X-Differential revision:	https://reviews.freebsd.org/D7302

Update #3175.

0 files changed, 0 insertions, 0 deletions