K 10
svn:author
V 3
mjg
K 8
svn:date
V 27
2020-11-19T19:25:47.538733Z
K 7
svn:log
V 335
pipe: thundering herd problem in pipelock

All reads and writes are serialized with a hand-rolled lock, but unlocking it
always wakes up all waiters. Existing flag fields get resized to make room for
introduction of waiter counter without growing the struct.

Reviewed by:	kib
Differential Revision:	https://reviews.freebsd.org/D27273

END