Commit Graph

30 Commits

Author SHA1 Message Date
Matt Joras
d6160f6079 Fix initialization of eventhandler mutex.
mtx_init does not do a copy of the name string it is passed. The
eventhandler code incorrectly passed the parameter string directly to
mtx_init instead of using the copy it makes. This was an existing
problem with the code that I dutifully copied over in my changes in r325621.

Reported by:	Anton Rang <rang AT acm.org>
Reviewed by:	rstone, markj
Approved by:	rstone (mentor)
MFC after:	1 week
Sponsored by:	Dell EMC Isilon
Differential Revision:	https://reviews.freebsd.org/D14764
2018-03-19 22:43:27 +00:00
Pedro F. Giffuni
8a36da99de sys/kern: adoption of SPDX licensing ID tags.
Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.
2017-11-27 15:20:12 +00:00
Matt Joras
2ca45184dc Introduce EVENTHANDLER_LIST and some users.
This introduces a facility to EVENTHANDLER(9) for explicitly defining a
reference to an event handler list. This is useful since previously all
invokers of events had to do a locked traversal of the global list of
event handler lists in order to find the appropriate event handler list.
By keeping a pointer to the appropriate list an invoker can avoid this
traversal completely. The pointer is initialized with SYSINIT(9) during
the eventhandler stage. Users registering interest in events do not need
to know if the event is backed by such a list, since the list is added
to the global list of lists. As with lists that are not pre-defined it
is safe to register for the events before the list has been created.

This converts the process_* and thread_* events to using the new
facility, as these are events whose locked traversals end up showing up
significantly in ports build workflows (and presumably other workflows
with many short lived threads/procs). It may be advantageous to convert
other events to using the new facility.

The el_flags field is now unused, but leave it be so that this revision
can be MFC'd.

Reviewed by:	bdrewery, markj, mjg
Approved by:	rstone (mentor)
In collaboration with:  ian
MFC after:      4 weeks
Sponsored by:	Dell EMC Isilon
Differential Revision:	https://reviews.freebsd.org/D12814
2017-11-09 22:51:48 +00:00
Ian Lepore
fc09164658 Restore the ability to deregister an eventhandler from within the callback.
When the EVENTHANDLER(9) subsystem was created, it was a documented feature
that an eventhandler callback function could safely deregister itself. In
r200652 that feature was inadvertantly broken by adding drain-wait logic to
eventhandler_deregister(), so that it would be safe to unload a module upon
return from deregistering its event handlers.

There are now 145 callers of EVENTHANDLER_DEREGISTER(), and it's likely many
of them are depending on the drain-wait logic that has been in place for 8
years. So instead of creating a separate eventhandler_drain() and adding it
to some or all of those 145 call sites, this creates a separate
eventhandler_drain_nowait() function for the specific purpose of
deregistering a callback from within the running callback.

Differential Revision:	https://reviews.freebsd.org/D12561
2017-10-08 17:21:16 +00:00
Bjoern A. Zeeb
42eedeac00 Split eventhandler_register() into an internal part and a wrapper function
that provides the allocated and setup eventhandler entry.

Add a new wrapper for VIMAGE that allocates extra space to hold the
callback function and argument in addition to an extra wrapper function.
While the wrapper function goes as normal callback function the
argument points to the extra space allocated holding the original func
and arg that the wrapper function can then call.

Provide an iterator function for the virtual network stack (vnet) that
will call the callback function for each network stack.

Provide a new set of macros for VNET that in the non-VIMAGE case will
just call eventhandler_register() while in the VIMAGE case it will use
vimage_eventhandler_register() passing in the extra iterator function
but will only register once rather than per-vnet.
We need a special macro in case we are interested in the tag returned
as we must check for curvnet and can neither simply assign the
return value, nor not change it in the non-vnet0 case without that.

Sponsored by:	ISPsystem
Discussed with:	jhb
Reviewed by:	zec (earlier version), jhb
MFC after:	1 month
2010-03-19 19:51:03 +00:00
Andrew Thompson
2b54315009 If the runcount is non-zero in eventhandler_deregister() then one or more
threads are executing the eventhandler, sleep in this case to make it safe for
module unload. If the runcount was up then an entry would have been marked
EHE_DEAD_PRIORITY so use this as a trigger to do the wakeup in
eventhandler_prune_list().

Reviewed by:	jhb
2009-12-17 21:17:13 +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
Sam Leffler
15ecf3968d eliminate potential null deref
Noticed by:	Coverity Prevent analysis tool
Reviewed by:	jhb
2005-02-23 19:32:29 +00:00
Joseph Koshy
fdf20233c7 Use 'const char *' for a few prototypes.
Reviewed by:	ru
2004-12-06 10:53:40 +00:00
David E. O'Brien
677b542ea2 Use __FBSDID(). 2003-06-11 00:56:59 +00:00
John Baldwin
ecdf4409f9 Rework the eventhandler locking for hopefully the last time. The scheme
used popped into my head during my morning commute a few weeks ago, but
it is also very similar (though a bit simpler) to a patch that mini@
developed a while ago.  Basically, each eventhandler list has a mutex and
a run count.  During an eventhandler invocation, the mutex is held while
we traverse the list but is dropped while we execute actual handlers.  Also,
a runcount counter is incremented at the start of an invocation and
decremented at the end of an invocation.  Adding to the list is not a big
deal since the reference of a thread currently executing the handlers
remains valid across an add operation.  Whether or not new handlers are
executed by threads currently executing the handlers for a given list is
indeterminate however.  The harder case is when a handler is removed from
the list.  If the runcount is zero, the handler is simply removed from the
list directly.  If the runcount is not zero, then another thread is
currently executing the handlers of this list, so the priority of this
handler is set to a magic value (currently -1) to mark it as dead.  Dead
handlers are not executed during an invocation.  If the runcount is zero
after it is decremented at the end of an invocation, then a new
eventhandler_prune_list() function is called to remove dead handlers from
the list.

Additional minor notes:
- All the common parts of EVENTHANDLER_INVOKE() and
  EVENTHANDLER_FAST_INVOKE() have been merged into a common
  _EVENTHANDLER_INVOKE() macro to reduce duplication and ease maintenance.
- KTR logging for eventhandlers is now available via the KTR_EVH mask.
- The global eventhander_mutex is no longer recursive.

Tested by:	scottl (SMP i386)
2003-03-11 20:17:00 +00:00
Maxime Henrion
0f3b0aa87c Wrap a line longer than 80 characters. 2002-07-19 17:44:44 +00:00
John Baldwin
6008862bc2 Change callers of mtx_init() to pass in an appropriate lock type name. In
most cases NULL is passed, but in some cases such as network driver locks
(which use the MTX_NETWORK_LOCK macro) and UMA zone locks, a name is used.

Tested on:	i386, alpha, sparc64
2002-04-04 21:03:38 +00:00
Alfred Perlstein
19a0f7e1be Avoid a lock order reversal by dropping the eventhandler_mutex earlier.
We get enough protection from the lock on the individual lists that we
aquire later.

Noticed/Tested by: Steven G. Kargl <kargl@troutmask.apl.washington.edu>
Submitted by: Jonathan Mini <mini@haikugeek.com>
2002-04-04 00:52:03 +00:00
Alfred Perlstein
28fe1a715e Use sx locks rather than lockmgr locks for eventhandlers.
Submitted by: Jonathan Mini <mini@haikugeek.com>
2002-04-02 04:18:54 +00:00
Julian Elischer
b40ce4165d KSE Milestone 2
Note ALL MODULES MUST BE RECOMPILED
make the kernel aware that there are smaller units of scheduling than the
process. (but only allow one thread per process at this time).
This is functionally equivalent to teh previousl -current except
that there is a thread associated with each process.

Sorry john! (your next MFC will be a doosie!)

Reviewed by: peter@freebsd.org, dillon@freebsd.org

X-MFC after:    ha ha ha ha
2001-09-12 08:38:13 +00:00
Jake Burkholder
146be906a1 Don't try to find an eventhandler list if the list of lists hasn't
been initialized yet.
2001-07-31 03:52:16 +00:00
Mark Murray
fb919e4d5a Undo part of the tangle of having sys/lock.h and sys/mutex.h included in
other "system" header files.

Also help the deprecation of lockmgr.h by making it a sub-include of
sys/lock.h and removing sys/lockmgr.h form kernel .c files.

Sort sys/*.h includes where possible in affected files.

OK'ed by:	bde (with reservations)
2001-05-01 08:13:21 +00:00
John Baldwin
f34fa851e0 Catch up to header include changes:
- <sys/mutex.h> now requires <sys/systm.h>
- <sys/mutex.h> and <sys/sx.h> now require <sys/lock.h>
2001-03-28 09:17:56 +00:00
Bosko Milekic
9ed346bab0 Change and clean the mutex lock interface.
mtx_enter(lock, type) becomes:

mtx_lock(lock) for sleep locks (MTX_DEF-initialized locks)
mtx_lock_spin(lock) for spin locks (MTX_SPIN-initialized)

similarily, for releasing a lock, we now have:

mtx_unlock(lock) for MTX_DEF and mtx_unlock_spin(lock) for MTX_SPIN.
We change the caller interface for the two different types of locks
because the semantics are entirely different for each case, and this
makes it explicitly clear and, at the same time, it rids us of the
extra `type' argument.

The enter->lock and exit->unlock change has been made with the idea
that we're "locking data" and not "entering locked code" in mind.

Further, remove all additional "flags" previously passed to the
lock acquire/release routines with the exception of two:

MTX_QUIET and MTX_NOSWITCH

The functionality of these flags is preserved and they can be passed
to the lock/unlock routines by calling the corresponding wrappers:

mtx_{lock, unlock}_flags(lock, flag(s)) and
mtx_{lock, unlock}_spin_flags(lock, flag(s)) for MTX_DEF and MTX_SPIN
locks, respectively.

Re-inline some lock acq/rel code; in the sleep lock case, we only
inline the _obtain_lock()s in order to ensure that the inlined code
fits into a cache line. In the spin lock case, we inline recursion and
actually only perform a function call if we need to spin. This change
has been made with the idea that we generally tend to avoid spin locks
and that also the spin locks that we do have and are heavily used
(i.e. sched_lock) do recurse, and therefore in an effort to reduce
function call overhead for some architectures (such as alpha), we
inline recursion for this case.

Create a new malloc type for the witness code and retire from using
the M_DEV type. The new type is called M_WITNESS and is only declared
if WITNESS is enabled.

Begin cleaning up some machdep/mutex.h code - specifically updated the
"optimized" inlined code in alpha/mutex.h and wrote MTX_LOCK_SPIN
and MTX_UNLOCK_SPIN asm macros for the i386/mutex.h as we presently
need those.

Finally, caught up to the interface changes in all sys code.

Contributors: jake, jhb, jasone (in no particular order)
2001-02-09 06:11:45 +00:00
Bosko Milekic
08812b3925 Implement MTX_RECURSE flag for mtx_init().
All calls to mtx_init() for mutexes that recurse must now include
the MTX_RECURSE bit in the flag argument variable. This change is in
preparation for an upcoming (further) mutex API cleanup.
The witness code will call panic() if a lock is found to recurse but
the MTX_RECURSE bit was not set during the lock's initialization.

The old MTX_RECURSE "state" bit (in mtx_lock) has been renamed to
MTX_RECURSED, which is more appropriate given its meaning.

The following locks have been made "recursive," thus far:
eventhandler, Giant, callout, sched_lock, possibly some others declared
in the architecture-specific code, all of the network card driver locks
in pci/, as well as some other locks in dev/ stuff that I've found to
be recursive.

Reviewed by: jhb
2001-01-19 01:59:14 +00:00
John Baldwin
06592dd188 - Convert the per-eventhandler list mutex to a lockmgr lock so that it can
be safely held across an eventhandler function call.
- Fix an instance of the head of an eventhandler list being read without
  the lock being held.
- Break down and use a SYSINIT at the new SI_SUB_EVENTHANDLER to initialize
  the eventhandler global mutex and the eventhandler list of lists rather
  than using a non-MP safe initialization during the first call to
  eventhandler_register().
- Add in a KASSERT() to eventhandler_register() to ensure that we don't try
  to register an eventhandler before things have been initialized.
2000-12-12 04:01:35 +00:00
Poul-Henning Kamp
959b7375ed Staticize some malloc M_ instances. 2000-12-08 20:09:00 +00:00
John Baldwin
d543796f86 - Make the eventhandler_mutex mutex a private variable in
subr_eventhandler.c
- Move the extra #include's in sys/eventhandler.h to be protected by
  the #ifndef SYS_EVENTHANDLER/#endif
2000-10-25 00:01:39 +00:00
Mike Smith
6595c331f3 Make the EVENTHANDLER mechanism MP-safe. Events can now be invoked
without holding the Giant lock.
2000-09-22 03:17:35 +00:00
Jake Burkholder
e39756439c Back out the previous change to the queue(3) interface.
It was not discussed and should probably not happen.

Requested by:		msmith and others
2000-05-26 02:09:24 +00:00
Jake Burkholder
740a1973a6 Change the way that the queue(3) structures are declared; don't assume that
the type argument to *_HEAD and *_ENTRY is a struct.

Suggested by:	phk
Reviewed by:	phk
Approved by:	mdodd
2000-05-23 20:41:01 +00:00
Poul-Henning Kamp
1b7277516b Commit the remaining part of PR14914:
Alot of the code in sys/kern directly accesses the *Q_HEAD and *Q_ENTRY
   structures for list operations.  This patch makes all list operations
   in sys/kern use the queue(3) macros, rather than directly accessing the
   *Q_{HEAD,ENTRY} structures.

Reviewed by:    phk
Submitted by:   Jake Burkholder <jake@checker.org>
PR:     14914
1999-11-16 16:28:58 +00:00
Peter Wemm
c3aac50f28 $Id$ -> $FreeBSD$ 1999-08-28 01:08:13 +00:00
Mike Smith
fcb893a801 Implement a new generic mechanism for attaching handler functions to
events, in order to pave the way for removing a number of the ad-hoc
implementations currently in use.

Retire the at_shutdown family of functions and replace them with
new event handler lists.

Rework kern_shutdown.c to take greater advantage of the use of event
handlers.

Reviewed by:	green
1999-08-21 06:24:40 +00:00