Commit Graph

278 Commits

Author SHA1 Message Date
Matthew D Fleming
4e6571599b Re-add r212370 now that the LOR in powerpc64 has been resolved:
Add a drain function for struct sysctl_req, and use it for a variety
of handlers, some of which had to do awkward things to get a large
enough SBUF_FIXEDLEN buffer.

Note that some sysctl handlers were explicitly outputting a trailing
NUL byte.  This behaviour was preserved, though it should not be
necessary.

Reviewed by:    phk (original patch)
2010-09-16 16:13:12 +00:00
Matthew D Fleming
404a593e28 Revert r212370, as it causes a LOR on powerpc. powerpc does a few
unexpected things in copyout(9) and so wiring the user buffer is not
sufficient to perform a copyout(9) while holding a random mutex.

Requested by: nwhitehorn
2010-09-13 18:48:23 +00:00
Matthew D Fleming
dd67e2103c Add a drain function for struct sysctl_req, and use it for a variety of
handlers, some of which had to do awkward things to get a large enough
FIXEDLEN buffer.

Note that some sysctl handlers were explicitly outputting a trailing NUL
byte.  This behaviour was preserved, though it should not be necessary.

Reviewed by:	phk
2010-09-09 18:33:46 +00:00
Rui Paulo
55820e298a Bump the witness pendlist to 768 to accomodate the increased number of
spinlocks.
2010-07-29 16:13:26 +00:00
Alexander Motin
6519968e59 "time lock" is no longer a spin-lock since r209371.
Reported by:	kib@
2010-06-21 21:15:51 +00:00
Attilio Rao
98332c8c71 Right now, WITNESS just blindly pipes all the output to the
(TOCONS | TOLOG) mask even when called from DDB points.
That breaks several output, where the most notable is textdump output.
Fix this by having configurable callbacks passed to witness_list_locks()
and witness_display_spinlock() for printing out datas.

Reported by:	several broken textdump outputs
Tested by:	Giovanni Trematerra
		<giovanni dot trematerra at gmail dot com>
MFC after:	7 days
X-MFC:		r207922
2010-05-11 18:24:22 +00:00
Attilio Rao
3caaaae046 There is not a good reason to have a different prototype for db_printf()
when compared to printf().
Unify it by returning the number of characters displayed for db_printf()
as well.

MFC after:	7 days
2010-05-11 17:01:14 +00:00
Kip Macy
2965a45315 On Alan's advice, rather than do a wholesale conversion on a single
architecture from page queue lock to a hashed array of page locks
(based on a patch by Jeff Roberson), I've implemented page lock
support in the MI code and have only moved vm_page's hold_count
out from under page queue mutex to page lock. This changes
pmap_extract_and_hold on all pmaps.

Supported by: Bitgravity Inc.

Discussed with: alc, jeffr, and kib
2010-04-30 00:46:43 +00:00
Edward Tomasz Napierala
6cb02977e2 SLIP is gone; remove its mutex from witness. 2009-12-29 08:45:27 +00:00
Antoine Brodin
bf3f1fe043 Change w_notrunning and w_stillcold from pointer to array so that sizeof
returns what is expected.

PR:		kern/138557
Discussed with:	brucec@
MFC after:	1 month
2009-09-06 13:31:05 +00:00
Kip Macy
126f8425c3 Add minimal ZFS lock hierarchy 2009-05-20 02:51:48 +00:00
Bruce M Simpson
33cde13046 Bite the bullet, and make the IPv6 SSM and MLDv2 mega-commit:
import from p4 bms_netdev.  Summary of changes:

 * Connect netinet6/in6_mcast.c to build.
   The legacy KAME KPIs are mostly preserved.
 * Eliminate now dead code from ip6_output.c.
   Don't do mbuf bingo, we are not going to do RFC 2292 style
   CMSG tricks for multicast options as they are not required
   by any current IPv6 normative reference.
 * Refactor transports (UDP, raw_ip6) to do own mcast filtering.
   SCTP, TCP unaffected by this change.
 * Add ip6_msource, in6_msource structs to in6_var.h.
 * Hookup mld_ifinfo state to in6_ifextra, allocate from
   domifattach path.
 * Eliminate IN6_LOOKUP_MULTI(), it is no longer referenced.
   Kernel consumers which need this should use in6m_lookup().
 * Refactor IPv6 socket group memberships to use a vector (like IPv4).
 * Update ifmcstat(8) for IPv6 SSM.
 * Add witness lock order for IN6_MULTI_LOCK.
 * Move IN6_MULTI_LOCK out of lower ip6_output()/ip6_input() paths.
 * Introduce IP6STAT_ADD/SUB/INC/DEC as per rwatson's IPv4 cleanup.
 * Update carp(4) for new IPv6 SSM KPIs.
 * Virtualize ip6_mrouter socket.
   Changes mostly localized to IPv6 MROUTING.
 * Don't do a local group lookup in MROUTING.
 * Kill unused KAME prototypes in6_purgemkludge(), in6_restoremkludge().
 * Preserve KAME DAD timer jitter behaviour in MLDv1 compatibility mode.
 * Bump __FreeBSD_version to 800084.
 * Update UPDATING.

NOTE WELL:
 * This code hasn't been tested against real MLDv2 queriers
   (yet), although the on-wire protocol has been verified in Wireshark.
 * There are a few unresolved issues in the socket layer APIs to
   do with scope ID propagation.
 * There is a LOR present in ip6_output()'s use of
   in6_setscope() which needs to be resolved. See comments in mld6.c.
   This is believed to be benign and can't be avoided for the moment
   without re-introducing an indirect netisr.

This work was mostly derived from the IGMPv3 implementation, and
has been sponsored by a third party.
2009-04-29 19:19:13 +00:00
Robert Watson
3dab55bc86 Decompose the global UNIX domain sockets rwlock into two different
locks: a global list/counter/generation counter protected by a new
mutex unp_list_lock, and a global linkage rwlock, unp_global_rwlock,
which protects the connections between UNIX domain sockets.

This eliminates conditional lock acquisition that was previously a
property of the global lock being held over sonewconn() leading to a
call to uipc_attach(), which also required the global lock, but
couldn't rely on it as other paths existed to uipc_attach() that
didn't hold it: now uipc_attach() uses only the list lock, which
follows the linkage lock in the lock order.  It may also reduce
contention on the global lock for some workloads.

Add global UNIX domain socket locks to hard-coded witness lock
order.

MFC after:	1 week
Discussed with:	kris
2009-03-08 21:48:29 +00:00
Andrew Thompson
fef11cb704 Move the NORELEASE check to after the recurse count decrement and bailout, this
is not counted as actually releasing the lock.
2009-02-28 19:10:43 +00:00
Warner Losh
8260e3a4c0 o Use unsigned for bit fields.
o Use NULL for pointers in preference to 0.
2009-02-03 07:50:41 +00:00
Andrew Thompson
018cecb61b Add functions WITNESS so it can be asserted that the lock is not released for a
section of code, this uses WITNESS_NORELEASE() and WITNESS_RELEASEOK() to mark
the boundaries. Both functions require the lock to be held when calling.

This is intended for scenarios like a bus asserting that the bus lock is not
dropped during a driver call. There doesn't appear to be a man page to
document this in.

Reviewed by:	jhb
2009-01-21 04:19:18 +00:00
Kip Macy
3120b9d428 - convert radix node head lock from mutex to rwlock
- make radix node head lock not recursive
 - fix LOR in rtexpunge
 - fix LOR in rtredirect

Reviewed by:	sam
2008-12-07 21:15:43 +00:00
Dag-Erling Smørgrav
e11e3f187d Fix a number of style issues in the MALLOC / FREE commit. I've tried to
be careful not to fix anything that was already broken; the NFSv4 code is
particularly bad in this respect.
2008-10-23 20:26:15 +00:00
Dag-Erling Smørgrav
1ede983cc9 Retire the MALLOC and FREE macros. They are an abomination unto style(9).
MFC after:	3 months
2008-10-23 15:53:51 +00:00
Attilio Rao
ca86d51602 In the actual code for witness_warn:
- If there aren't spinlocks held, but there are problems with old
  sleeplocks, they are not reported.
- If the spinlock found is not the only one, problems are not reported.

Fix these 2 problems.

Reported by:	tegge
2008-10-20 19:22:16 +00:00
Attilio Rao
ac0dd8886d - Fix a race in witness_checkorder() where, between the PCPU_GET() and
PCPU_PTR() curthread can migrate on another CPU and get incorrect
  results.
- Fix a similar race into witness_warn().
- Fix the interlock's checks bypassing by correctly using the appropriate
  children even when the lock_list chunk to be explored is not the first
  one.
- Allow witness_warn() to work with spinlocks too.

Bugs found by:	tegge
Submitted by:	jhb, tegge
Tested by:	Giovanni Trematerra <giovanni dot trematerra at gmail dot com>
2008-10-16 12:42:56 +00:00
John Baldwin
4ec9dc4de2 Oops, missed updating a place with with 's/lock1/plock/' when adding
interlock support to WITNESS.  Specifically, the printf listing the
first location when duplicate locks of the same type are acquired.

Reported by:	pho
2008-10-03 18:13:05 +00:00
John Baldwin
c1fa2e4200 Update description of witness_watch. 2008-09-24 18:47:24 +00:00
Sam Leffler
39297ba455 Make ddb command registration dynamic so modules can extend
the command set (only so long as the module is present):
o add db_command_register and db_command_unregister to add and remove
  commands, respectively
o replace linker sets with SYSINIT's (and SYSUINIT's) that register
  commands
o expose 3 list heads: db_cmd_table, db_show_table, and db_show_all_table
  for registering top-level commands, show operands, and show all operands,
  respectively

While here also:
o sort command lists
o add DB_ALIAS, DB_SHOW_ALIAS, and DB_SHOW_ALL_ALIAS to add aliases
  for existing commands
o add "show all trace" as an alias for "show alltrace"
o add "show all locks" as an alias for "show alllocks"

Submitted by:	Guillaume Ballet <gballet@gmail.com> (original version)
Reviewed by:	jhb
MFC after:	1 month
2008-09-15 22:45:14 +00:00
Attilio Rao
d56bc17bce - For any lock list we hold the head in order to reduce allocation from
the free list and in this way avoid contention on the w_mtx.
  In order to make the code simple, we rely on the rule that when the head
  has not a child it also doesn't have other subsequent entries.
  Actually this assertion is broken because we can free all the head
  children and quit witness_unlock() with the head still allocated, with no
  children and subsequent entries present.
  Fix this by shifting the head if other entries are present and still
  freeing the object, but leaving always an head.
- Fix witness_thread_has_locks() in order to report, correctly, if the
  lock list linked to a specific thread has children or not based on the
  above explained rule.
- Fix a printout into DDB's "show alllocks" command in order to show,
  correctly, the process name that is really what we want.
- Fix style(9) for a comment.

Tested by:	Giovanni Trematerra <giovanni dot trematerra at gmail dot com>
Reported by:	Marko Kiiskila <marko dot kiiskila at nokia dot com>
Sponsored by:	Nokia
2008-09-12 21:44:01 +00:00
John Baldwin
413134305e Teach WITNESS about the interlocks used with lockmgr. This removes a bunch
of spurious witness warnings since lockmgr grew witness support.  Before
this, every time you passed an interlock to a lockmgr lock WITNESS treated
it as a LOR.

Reviewed by:	attilio
2008-09-10 19:13:30 +00:00
Attilio Rao
988d28340a - Improve some witness_watch operability in code which does perform both
lock tracking and checks, doing just the former ones.
- Fix a bug where sysctl utility was printing crazy values when setting a
  new value for debug.witness.watch [0]

[0] Reported by:	yongari
2008-08-30 13:20:35 +00:00
Attilio Rao
df3310e04a - Make witness_watch a 3 state value.
1 means that witness is up and running.
  0 means that witness is disabled but that it can be established later
    again in effective way.
  -1 means that witness is disabled permanently
- Fix a bug causing kernel to panic on witness disabling through
  witness_watch.  lock lists queues were still full of entries and this was
  causing throubles with debugging stubs (like witness_thread_exit()).

Reported by:	kris, yongari
Sponsored by:	Nokia
2008-08-29 15:47:53 +00:00
Attilio Rao
3d06b4b330 Introduce some WITNESS improvements:
- Speedup the lock orderings lookup modifying the witness graph from a
  linked tree to a matrix. A table lookup caches the lock orderings in
  order to make a O(1) access for them. Any witness object has an unique
  index withing this lookup cache table.
- Reduce the lock contention on w_mtx acquiring it only when the LOR
  actually happens and not in a sane case. In order to do this don't totally
  flush lock lists (per-CPU spinlocks list and per-thread sleeplocks list)
  but check for ll_count anytime we need to have to verify allocations sanity.
- Introduce the function witness_thread_exit() in the witness namespace which
  should verify a thread doesn't hold any witness occurrence why exiting.
- Rename the sysctl debug.witness.graphs into debug.witness.fullgraph and
  add debug.witness.badstacks which prints out stacks for LOR revealed.
  This is implemented using the stack(9) support, which makes WITNESS to be
  dependent by the STACK option or by the DDB (including STACK) option.
- Fix style(9) for src/sys/kern/subr_witness.c

The hash table approach has been developed by Ilya Maykov on the behalf of
Isilon Systems which kindly released the patch.
Jeff Roberson, ported the patch to -CURRENT and fixed w_mtx contention, on the
behalf of Nokia.

Submitted by:	Ilya Maykov <ivmaykov at gmail dot com> (Isilon Systems), jeff
Sponsored by:	Nokia
2008-08-13 18:24:22 +00:00
Robert Watson
1a4b919f8e witness_addgraph() is required even if DDB isn't compiled into the kernel,
so exclude it from #ifdef DDB.

Submitted by:	attilio
2008-07-19 17:47:23 +00:00
Attilio Rao
90356491d7 - Embed the recursion counter for any locking primitive directly in the
lock_object, using an unified field called lo_data.
- Replace lo_type usage with the w_name usage and at init time pass the
  lock "type" directly to witness_init() from the parent lock init
  function.  Handle delayed initialization before than
  witness_initialize() is called through the witness_pendhelp structure.
- Axe out LO_ENROLLPEND as it is not really needed.  The case where the
  mutex init delayed wants to be destroyed can't happen because
  witness_destroy() checks for witness_cold and panic in case.
- In enroll(), if we cannot allocate a new object from the freelist,
  notify that to userspace through a printf().
- Modify the depart function in order to return nothing as in the current
  CVS version it always returns true and adjust callers accordingly.
- Fix the witness_addgraph() argument name prototype.
- Remove unuseful code from itismychild().

This commit leads to a shrinked struct lock_object and so smaller locks,
in particular on amd64 where 2 uintptr_t (16 bytes per-primitive) are
gained.

Reviewed by:	jhb
2008-05-15 20:10:06 +00:00
Attilio Rao
688b98135c Add a new witness sysctl which returns the relations between any lock
and its children in the form:
"parent","child"
so that head and bottom of an oriented graph can be easilly detected and
various form of diagrams can be build.
The sysctl is called debug.witness.graphs and it is read-only; in order
to get the list of relations, a simple:
#sysctl debug.witness.graphs
will do the trick.

This approach has been choosen in order to support easilly things like
the DOT format and such.  Soon, an auto-explicative awk script, which
filters simple informations returned by the sysctl and converts them into
a real DOT script, will be committed to the repository between examples.

Discussed with:	rwatson
2008-05-07 21:41:36 +00:00
Robert Watson
8501a69cc9 Convert pcbinfo and inpcb mutexes to rwlocks, and modify macros to
explicitly select write locking for all use of the inpcb mutex.
Update some pcbinfo lock assertions to assert locked rather than
write-locked, although in practice almost all uses of the pcbinfo
rwlock main exclusive, and all instances of inpcb lock acquisition
are exclusive.

This change should introduce (ideally) little functional change.
However, it lays the groundwork for significantly increased
parallelism in the TCP/IP code.

MFC after:	3 months
Tested by:	kris (superset of committered patch)
2008-04-17 21:38:18 +00:00
Attilio Rao
0b0100db88 struct lock_instance and struct lock_list_entry don't need to be in the
public namespace for WITNESS as they are only used internally so just
move them in the private namespace for the subsystem (with all related
supporting definitions).
2008-04-13 01:20:47 +00:00
Attilio Rao
e5f94314ad - Re-introduce WITNESS support for lockmgr. About the old implementation
the only one difference is that lockmgr*() functions now accept
  LK_NOWITNESS flag which skips ordering for the instanced calling.
- Remove an unuseful stub in witness_checkorder() (because the above check
  doesn't allow ever happening) and allow witness_upgrade() to accept
  non-try operation too.
2008-04-12 19:57:30 +00:00
Attilio Rao
1859cffaef Add missing stubs for spinlocks cpuset and intrcnt.
Submitted by:	kris
2008-04-12 13:51:18 +00:00
Pawel Jakub Dawidek
4582cb68b1 - There is no more "uidinfo struct" mutex.
- The "uidinfo hash" lock is now a rwlock.

Reminded by:	kib
2008-03-17 11:48:40 +00:00
Robert Watson
237fdd787b In keeping with style(9)'s recommendations on macros, use a ';'
after each SYSINIT() macro invocation.  This makes a number of
lightweight C parsers much happier with the FreeBSD kernel
source, including cflow's prcc and lxr.

MFC after:	1 month
Discussed with:	imp, rink
2008-03-16 10:58:09 +00:00
Jeff Roberson
6617724c5f Remove kernel support for M:N threading.
While the KSE project was quite successful in bringing threading to
FreeBSD, the M:N approach taken by the kse library was never developed
to its full potential.  Backwards compatibility will be provided via
libmap.conf for dynamically linked binaries and static binaries will
be broken.
2008-03-12 10:12:01 +00:00
Rafal Jaworowski
6b7ba54456 Initial support for Freescale PowerQUICC III MPC85xx system-on-chip family.
The PQ3 is a high performance integrated communications processing system
based on the e500 core, which is an embedded RISC processor that implements
the 32-bit Book E definition of the PowerPC architecture. For details refer
to: http://www.freescale.com/webapp/sps/site/prod_summary.jsp?code=MPC8555E

This port was tested and successfully run on the following members of the PQ3
family: MPC8533, MPC8541, MPC8548, MPC8555.

The following major integrated peripherals are supported:

  * On-chip peripherals bus
  * OpenPIC interrupt controller
  * UART
  * Ethernet (TSEC)
  * Host/PCI bridge
  * QUICC engine (SCC functionality)

This commit brings the main functionality and will be followed by individual
drivers that are logically separate from this base.

Approved by:	cognet (mentor)
Obtained from:	Juniper, Semihalf
MFp4:		e500
2008-03-03 17:17:00 +00:00
Robert Watson
3de213cc00 Add a new 'why' argument to kdb_enter(), and a set of constants to use
for that argument.  This will allow DDB to detect the broad category of
reason why the debugger has been entered, which it can use for the
purposes of deciding which DDB script to run.

Assign approximate why values to all current consumers of the
kdb_enter() interface.
2007-12-25 17:52:02 +00:00
Attilio Rao
4a32616a77 Fix the spinlock static table adding missing spinlocks.
- rm_spinlock has turnstile chain as child
- srclock has callout and clk as child, found by witness "emulation".
  Just move it very high in our ranking
2007-11-24 04:32:32 +00:00
Julian Elischer
e01eafef2a A bunch more files that should probably print out a thread name
instead of a process name.
2007-11-14 06:51:33 +00:00
Attilio Rao
c8790f5d09 Fix some entries in the locks static table of witness.
In particular:
- smp_tlb_mtx is no longer used, so it is axed.
- smp rendezvous lock isn't really a leaf spin-mutex. Its bad placement in
  the table, however, has been the source of a false positive LOR reporting
  with the dt_lock.  However, smp rendezvous lock would have had sched_lock
  there for older lock, so it wasn't still a leaf lock.
- allpmaps is only used in ia32 architecture, so it is inserted in the
  appropriate stub.

Addictionally:
- kse_zombie_lock is no longer present, so its definition is axed out.
- zombie_lock doesn't need to have an exported symbol, so just let's it be
  declared as static.

Tested by: kris
Approved by: jeff (mentor)
Approved by: re
2007-09-20 20:38:43 +00:00
Marius Strobl
79be8b5082 - Remove zstty spin lock for no longer existing zs(4).
- Move the rtc_mtx spin lock out from under #ifdef SMP as it's just
  not SMP-specific.
- Add a new spin lock pcib_mtx for locking "fast" interrupt handlers
  of host-to-PCI bridge drivers on sparc64.
2007-06-16 23:30:57 +00:00
Sam Leffler
68e8e04e93 Update 802.11 wireless support:
o major overhaul of the way channels are handled: channels are now
  fully enumerated and uniquely identify the operating characteristics;
  these changes are visible to user applications which require changes
o make scanning support independent of the state machine to enable
  background scanning and roaming
o move scanning support into loadable modules based on the operating
  mode to enable different policies and reduce the memory footprint
  on systems w/ constrained resources
o add background scanning in station mode (no support for adhoc/ibss
  mode yet)
o significantly speedup sta mode scanning with a variety of techniques
o add roaming support when background scanning is supported; for now
  we use a simple algorithm to trigger a roam: we threshold the rssi
  and tx rate, if either drops too low we try to roam to a new ap
o add tx fragmentation support
o add first cut at 802.11n support: this code works with forthcoming
  drivers but is incomplete; it's included now to establish a baseline
  for other drivers to be developed and for user applications
o adjust max_linkhdr et. al. to reflect 802.11 requirements; this eliminates
  prepending mbufs for traffic generated locally
o add support for Atheros protocol extensions; mainly the fast frames
  encapsulation (note this can be used with any card that can tx+rx
  large frames correctly)
o add sta support for ap's that beacon both WPA1+2 support
o change all data types from bsd-style to posix-style
o propagate noise floor data from drivers to net80211 and on to user apps
o correct various issues in the sta mode state machine related to handling
  authentication and association failures
o enable the addition of sta mode power save support for drivers that need
  net80211 support (not in this commit)
o remove old WI compatibility ioctls (wicontrol is officially dead)
o change the data structures returned for get sta info and get scan
  results so future additions will not break user apps
o fixed tx rate is now maintained internally as an ieee rate and not an
  index into the rate set; this needs to be extended to deal with
  multi-mode operation
o add extended channel specifications to radiotap to enable 11n sniffing

Drivers:
o ath: add support for bg scanning, tx fragmentation, fast frames,
       dynamic turbo (lightly tested), 11n (sniffing only and needs
       new hal)
o awi: compile tested only
o ndis: lightly tested
o ipw: lightly tested
o iwi: add support for bg scanning (well tested but may have some
       rough edges)
o ral, ural, rum: add suppoort for bg scanning, calibrate rssi data
o wi: lightly tested

This work is based on contributions by Atheros, kmacy, sephe, thompsa,
mlaier, kevlo, and others.  Much of the scanning work was supported by
Atheros.  The 11n work was supported by Marvell.
2007-06-11 03:36:55 +00:00
Jeff Roberson
bd43e47156 Commit 10/14 of sched_lock decomposition.
- Add new spinlocks to support thread_lock() and adjust ordering.

Tested by:      kris, current@
Tested on:      i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc.
Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:55:45 +00:00
Attilio Rao
02b0a160dc Fix some problems introduced with the last descriptors tables locking
patch:
- Do the correct test for ldt allocation
- Drop dt_lock just before to call kmem_free (since it acquires blocking
  locks inside)
- Solve a deadlock with smp_rendezvous() where other CPU will wait
  undefinitively for dt_lock acquisition.
- Add dt_lock in the WITNESS list of spinlocks

While applying these modifies, change the requirement for user_ldt_free()
making that returning without dt_lock held.

Tested by: marcus, tegge
Reviewed by: tegge
Approved by: jeff (mentor)
2007-05-29 18:55:41 +00:00
Jeff Roberson
8b98fec903 - Move clock synchronization into a seperate clock lock so the global
scheduler lock is not involved.  sched_lock still protects the sched_clock
   call.  Another patch will remedy this.

Contributed by:	Attilio Rao <attilio@FreeBSD.org>
Tested by:	kris, jeff
2007-05-20 22:11:50 +00:00
Joseph Koshy
382d30cdd8 Fix witness(4) warnings about mutex use.
Group mutexes used in hwpmc(4) into 3 "types" in the sense of
witness(4):

 - leaf spin mutexes---only one of these should be held at a time,
   so these mutexes are specified as belonging to a single witness
   type "pmc-leaf".

 - `struct pmc_owner' descriptors are protected by a spin mutex of
   witness type "pmc-owner-proc".  Since we call wakeup_one() while
   holding these mutexes, the witness type of these mutexes needs
   to dominate that of "sleepq chain" mutexes.

 - logger threads use a sleep mutex, of type "pmc-sleep".

Submitted by:	wkoszek (earlier patch)
2007-04-19 08:02:51 +00:00