As far as I can tell, there is no reason to ignore unlocks, ever;
if no threads are waiting, then mutex_unlock() will act appropriately.
So all we need to do is increment the lock's count here,
as we are relinquishing our request for locking.
On the other hand, if we did not find our structure in the lock,
that means we own the lock; so to return with an error from here
without changing the count would result in a deadlock, as the lock
would then be ours, despite our error code implying otherwise.
Additionally, take care of part of the case where we have woken up
by mutex_destroy(), by setting thread to NULL and checking for it
in that case. There is still a race here, however.
May fix#16044, as it appears there is a case where ACPICA
calls this with a timeout of 0 (we should make this be
a mutex_trylock, anyway.)
Change-Id: I98215df218514c70ac1922bc3a6f10e01087e44b
Reviewed-on: https://review.haiku-os.org/c/haiku/+/2716
Reviewed-by: waddlesplash <waddlesplash@gmail.com>
Non-KDEBUG kernels and kernel add-ons use atomic operations to acquire
and release the locks inline, so non-KDEBUG kernels/addons are only
compatible with other non-KDEBUG kernels/addons.
Following this change, though, KDEBUG kernels/addons should be able
to run under non-KDEBUG kernels/addons, too, since they always call
into the actual kernel functions and do not inline anything of
consequence.
* mutex_destroy() only checked wether or not there were waiters,
not if the lock itself was presently held by another thread.
Now we do, which should make #15015 panic much earlier instead
of trying to use freed memory.
* mutex_transfer_lock() and recursive_lock_transfer_lock() did
not check that the calling thread actually owned the lock.
Now it does, which should trigger asserts if anyone tries
to do this.
* Reorganized the kernel locking related to threads and teams.
* We now discriminate correctly between process and thread signals. Signal
handlers have been moved to teams. Fixes#5679.
* Implemented real-time signal support, including signal queuing, SA_SIGINFO
support, sigqueue(), sigwaitinfo(), sigtimedwait(), waitid(), and the addition
of the real-time signal range. Closes#1935 and #2695.
* Gave SIGBUS a separate signal number. Fixes#6704.
* Implemented <time.h> clock and timer support, and fixed/completed alarm() and
[set]itimer(). Closes#5682.
* Implemented support for thread cancellation. Closes#5686.
* Moved send_signal() from <signal.h> to <OS.h>. Fixes#7554.
* Lots over smaller more or less related changes.
git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@42116 a95241bf-73f2-0310-859d-f6bbb57e9c96
* Changed the rw_lock_{read,write}_unlock() return values to void. They
returned a value != B_OK only in case of user error and no-one checked them
anyway.
* Optimized rw_lock_read_[un]lock(). They are inline now and as long as
there's no contending write locker, they will only perform an atomic_add().
* Changed the semantics of nested locking after acquiring a write lock: Read
and write locks are counted separately, so read locks no longer implicitly
become write locks. This does e.g. make degrading a write lock to a read
lock by way of read_lock + write_unlock (as used in the VM) actually work.
These changes speed up the -j8 Haiku image build on my machine by a few
percent, but more interestingly they reduce the total kernel time by 25 %.
Apparently we get more contention on other locks, now.
git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@34830 a95241bf-73f2-0310-859d-f6bbb57e9c96
high contention of the read lock (I experimented with the VM page mapping
lock)), it actually hurt the compile performance pretty obviously.
git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@33647 a95241bf-73f2-0310-859d-f6bbb57e9c96
makes the reader case a lot less expensive, and should relieve the thread
spinlock contention a bit.
git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@33643 a95241bf-73f2-0310-859d-f6bbb57e9c96
is defined to 1; this allows asserting the read lock case, too.
* Added ASSERT_{READ|WRITE}_LOCKED_RW_LOCK() macros. The read assertion is only
working when KDEBUG_RW_LOCK_DEBUG is defined to 1, the write assertion works
always.
git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@26686 a95241bf-73f2-0310-859d-f6bbb57e9c96
introduces the following relevant changes:
* VMCache:
- Renamed vm_cache to VMCache, merged it with vm_store and made it a
C++ class with virtual methods (replacing the store operations).
Turned the different store implementations into subclasses.
- Introduced MergeStore() callback, changed semantics of Commit().
- Changed locking and referencing semantics. A reference can only be
acquired/released with the cache locked. An unreferenced cache is
deleted and a mergeable cache merged when it is unlocked. This
removes the "busy" state of a cache and simplifies the page fault
code.
* Added VMAnonymousCache, which will implement swap support (work by
Zhao Shuai). It is not integrated and used yet, though.
* Enabled the mutex/recursive lock holder asserts.
* Fixed DoublyLinkedList::Swap().
* Generalized the low memory handler to a low resource handler. And made
semaphores and reserved memory handled resources. Made
vm_try_resource_memory() optionally wait (with timeout), and used that
feature to reserve memory for areas.
...
git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@26572 a95241bf-73f2-0310-859d-f6bbb57e9c96
It follows the semantics of the BFS R/W lock, though, that is, if you unlock
your write lock before the read locks, the read locks effectively become
write locks, too.
* Added a mutex_transfer_lock() function that will allow you to unlock a mutex
in a different thread than the one which locked it (only matters if KDEBUG
is enabled, though).
git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@26316 a95241bf-73f2-0310-859d-f6bbb57e9c96
than a semaphore, and can already be used in the early boot process.
git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@25689 a95241bf-73f2-0310-859d-f6bbb57e9c96
* Adjusted code using recursive locks respectively. The initialization
cannot fail anymore, and it is possible to use recursive locks in the
early boot process (even uninitialized, if in BSS), which simplifies
things a little.
git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@25687 a95241bf-73f2-0310-859d-f6bbb57e9c96
* Trivial adjustments of code using mutexes. Mostly removing the
mutex_init() return value check.
* Added mutex_lock_threads_locked(), which is called with the threads
spinlock being held. The spinlock is released while waiting, of
course. This function is useful in cases where the existence of the
mutex object is ensured by holding the threads spinlock.
* Changed the two instances in the VFS code where an IO context of
another team needs to be locked to use mutex_lock_threads_locked().
Before it required a semaphore-based mutex implementation.
git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@25283 a95241bf-73f2-0310-859d-f6bbb57e9c96
that can unlock the mutex, so one bit is sufficient.
* Added cutex_init_etc() which has an additional "flags" parameter.
The only specifyable flag is CUTEX_FLAG_CLONE_NAME, which causes the
function to strdup() the given name and free() its copy in
cutex_destroy().
* cutex_destroy() does now unblock waiting threads.
git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@25280 a95241bf-73f2-0310-859d-f6bbb57e9c96
name, couldn't resist :-P). It's semantically equivalent to a mutex,
but doesn't need a semaphore (it uses thread blocking and a simple
queue instead). Initialization can't fail. In fact it is ready to use
without initialization when living in the bss segment, also in the
early boot process. It's as fast as a benaphore in cases of low lock
contention, and faster otherwise. Only disadvantage is the higher
immediate memory footprint of 16 bytes.
* Changed how the "thread" and "threads" debugger commands list the
objects they are waiting for. Cutexes are also included.
git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@25276 a95241bf-73f2-0310-859d-f6bbb57e9c96
* Replaced release_sem() with release_sem_etc() for future addition of the
B_DO_NOT_RESCHEDULE flag.
git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@22308 a95241bf-73f2-0310-859d-f6bbb57e9c96
Disabled by default, but all kernel devs are *highly* recommended to turn them on for your builds and see if it trips anything, and then fix it.
git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@21477 a95241bf-73f2-0310-859d-f6bbb57e9c96
* recursive_lock_unlock() now returns a void to mirror it's counterpart better;
use recursive_lock_get_recursion() if you're interested in the lock depth.
* switch_sem(), and release_sem() now don't do anything anymore in kernel startup
mode.
git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@20099 a95241bf-73f2-0310-859d-f6bbb57e9c96
ones (but real functions/inlines this time).
Renamed recursive_lock_create() to recursive_lock_init() for consistency,
and added a "name" parameter.
Changed "int" return to status_t where appropriate.
git-svn-id: file:///srv/svn/repos/haiku/trunk/current@3676 a95241bf-73f2-0310-859d-f6bbb57e9c96
Changed lock.h to like those changes.
Moved the create_sem_etc() from the public OS.h to the private kernel only
sem.h, cleaned it up a bit.
gcc doesn't seem to like the "extern inlines" with -O0 -g, so I replaced
an inline function in thread.h with "static inline" (which it does always
like).
git-svn-id: file:///srv/svn/repos/haiku/trunk/current@1376 a95241bf-73f2-0310-859d-f6bbb57e9c96
benaphores; benaphores aren't that beneficial in kernel land, the benaphores
are a way to reduce the number of kernel calls.
They can now only be released by the same thread who originally acquired it.
git-svn-id: file:///srv/svn/repos/haiku/trunk/current@312 a95241bf-73f2-0310-859d-f6bbb57e9c96
