K 10
svn:author
V 3
kib
K 8
svn:date
V 27
2009-10-27T10:47:58.978326Z
K 7
svn:log
V 451
In r197963, a race with thread being selected for signal delivery
while in kernel mode, and later changing signal mask to block the
signal, was fixed for sigprocmask(2) and ptread_exit(3). The same race
exists for sigreturn(2), setcontext(2) and swapcontext(2) syscalls.

Use kern_sigprocmask() instead of direct manipulation of td_sigmask to
reschedule newly blocked signals, closing the race.

Reviewed by:	davidxu
Tested by:	pho
MFC after:	1 month

END