Several improvements to rmlock(9). Many of these are based on patches

provided by Isilon.
- Add an rm_assert() supporting various lock assertions similar to other
  locking primitives.  Because rmlocks track readers the assertions are
  always fully accurate unlike rw_assert() and sx_assert().
- Flesh out the lock class methods for rmlocks to support sleeping via
  condvars and rm_sleep() (but only while holding write locks), rmlock
  details in 'show lock' in DDB, and the lc_owner method used by
  dtrace.
- Add an internal destroyed cookie so that API functions can assert
  that an rmlock is not destroyed.
- Make use of rm_assert() to add various assertions to the API (e.g.
  to assert locks are held when an unlock routine is called).
- Give RM_SLEEPABLE locks their own lock class and always use the
  rmlock's own lock_object with WITNESS.
- Use THREAD_NO_SLEEPING() / THREAD_SLEEPING_OK() to disallow sleeping
  while holding a read lock on an rmlock.

Submitted by:	andre
Obtained from:	EMC/Isilon

2 files changed, 66 insertions, 8 deletions

diff --git a/share/man/man9/Makefile b/share/man/man9/Makefile
index e29aeec..fe4086f 100644
--- a/share/man/man9/Makefile
+++ b/share/man/man9/Makefile
@@ -1077,12 +1077,15 @@ MLINKS+=rman.9 rman_activate_resource.9 \
 	rman.9 rman_set_bustag.9 \
 	rman.9 rman_set_rid.9 \
 	rman.9 rman_set_virtual.9
-MLINKS+=rmlock.9 rm_destroy.9 \
+MLINKS+=rmlock.9 rm_assert.9 \
+	rmlock.9 rm_destroy.9 \
 	rmlock.9 rm_init.9 \
+	rmlock.9 rm_init_flags.9 \
 	rmlock.9 rm_rlock.9 \
-	rmlock.9 rm_try_rlock.9 \
 	rmlock.9 rm_runlock.9 \
+	rmlock.9 rm_sleep.9 \
 	rmlock.9 RM_SYSINIT.9 \
+	rmlock.9 rm_try_rlock.9 \
 	rmlock.9 rm_wlock.9 \
 	rmlock.9 rm_wowned.9 \
 	rmlock.9 rm_wunlock.9
diff --git a/share/man/man9/rmlock.9 b/share/man/man9/rmlock.9
index 7808345..aeb3b45 100644
--- a/share/man/man9/rmlock.9
+++ b/share/man/man9/rmlock.9
@@ -26,7 +26,7 @@
 .\" $FreeBSD$
 .\"
 .\" Based on rwlock.9 man page
-.Dd June 8, 2012
+.Dd June 25, 2013
 .Dt RMLOCK 9
 .Os
 .Sh NAME
@@ -40,6 +40,8 @@
 .Nm rm_runlock ,
 .Nm rm_wunlock ,
 .Nm rm_wowned ,
+.Nm rm_sleep ,
+.Nm rm_assert ,
 .Nm RM_SYSINIT
 .Nd kernel reader/writer lock optimized for read-mostly access patterns
 .Sh SYNOPSIS
@@ -64,6 +66,13 @@
 .Fn rm_wunlock "struct rmlock *rm"
 .Ft int
 .Fn rm_wowned "const struct rmlock *rm"
+.Ft int
+.Fn rm_sleep "void *wchan" "struct rmlock *rm" "int priority" "const char *wmesg" "int timo"
+.Pp
+.Cd "options INVARIANTS"
+.Cd "options INVARIANT_SUPPORT"
+.Ft void
+.Fn rm_assert "struct rmlock *rm" "int what"
 .In sys/kernel.h
 .Fn RM_SYSINIT "name" "struct rmlock *rm" "const char *desc" "int opts"
 .Sh DESCRIPTION
@@ -215,12 +224,63 @@ lock must be unlocked.
 This function returns a non-zero value if the current thread owns an
 exclusive lock on
 .Fa rm .
+.It Fn rm_sleep "void *wchan" "struct rmlock *rm" "int priority" "const char *wmesg" "int timo"
+This function atomically releases
+.Fa rm
+while waiting for an event.
+The
+.Fa rm
+lock must be exclusively locked.
+For more details on the parameters to this function,
+see
+.Xr sleep 9 .
+.It Fn rm_assert "struct rmlock *rm" "int what"
+This function asserts that the
+.Fa rm
+lock is in the state specified by
+.Fa what .
+If the assertions are not true and the kernel is compiled with
+.Cd "options INVARIANTS"
+and
+.Cd "options INVARIANT_SUPPORT" ,
+the kernel will panic.
+Currently the following base assertions are supported:
+.Bl -tag -width ".Dv RA_UNLOCKED"
+.It Dv RA_LOCKED
+Assert that current thread holds either a shared or exclusive lock
+of
+.Fa rm .
+.It Dv RA_RLOCKED
+Assert that current thread holds a shared lock of
+.Fa rm .
+.It Dv RA_WLOCKED
+Assert that current thread holds an exclusive lock of
+.Fa rm .
+.It Dv RA_UNLOCKED
+Assert that current thread holds neither a shared nor exclusive lock of
+.Fa rm .
+.El
+.Pp
+In addition, one of the following optional flags may be specified with
+.Dv RA_LOCKED ,
+.Dv RA_RLOCKED ,
+or
+.Dv RA_WLOCKED :
+.Bl -tag -width ".Dv RA_NOTRECURSED"
+.It Dv RA_RECURSED
+Assert that the current thread holds a recursive lock of
+.Fa rm .
+.It Dv RA_NOTRECURSED
+Assert that the current thread does not hold a recursive lock of
+.Fa rm .
+.El
 .El
 .Sh SEE ALSO
 .Xr locking 9 ,
 .Xr mutex 9 ,
 .Xr panic 9 ,
 .Xr rwlock 9 ,
+.Xr sleep 9 ,
 .Xr sema 9 ,
 .Xr sx 9
 .Sh HISTORY
@@ -252,8 +312,3 @@ implementation uses a single per CPU list shared by all
 rmlocks in the system.
 If rmlocks become popular, hashing to multiple per CPU queues may
 be needed to speed up the writer lock process.
-.Pp
-The
-.Nm
-can currently not be used as a lock argument for condition variable
-wait functions.