K 10
svn:author
V 3
kib
K 8
svn:date
V 27
2013-06-13T09:33:22.118430Z
K 7
svn:log
V 827
Fix two issues with the spin loops in the umtx(2) implementation.

- When looping, check for the pending suspension.  Otherwise, other
  usermode thread which races with the looping one, could try to
  prevent the process from stopping or exiting.

- Add missed checks for the faults from casuword*().  The code is
  structured in a way which makes the loops exit if the specified
  address is invalid, since both fuword() and casuword() return -1 on
  the fault.  But if the address is mapped readonly, the typical value
  read by fuword() is different from -1, while casuword() returns -1.
  Absent the checks for casuword() faults, this is interpreted as the
  race with other thread and causes non-interruptible spinning in the
  kernel.

Reported and tested by:	pho
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks

END