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* coroutine: Extract qemu_aio_coroutine_enterFam Zheng2017-04-111-0/+5
| | | | | | | | | It's a variant of qemu_coroutine_enter with an explicit AioContext parameter. Signed-off-by: Fam Zheng <famz@redhat.com> Acked-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com>
* coroutine-lock: make CoRwlock thread-safe and fairPaolo Bonzini2017-02-211-1/+2
| | | | | | | | | | | | | This adds a CoMutex around the existing CoQueue. Because the write-side can just take CoMutex, the old "writer" field is not necessary anymore. Instead of removing it altogether, count the number of pending writers during a read-side critical section and forbid further readers from entering. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com> Message-id: 20170213181244.16297-7-pbonzini@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* coroutine-lock: add mutex argument to CoQueue APIsPaolo Bonzini2017-02-211-3/+5
| | | | | | | | | | All that CoQueue needs in order to become thread-safe is help from an external mutex. Add this to the API. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com> Message-id: 20170213181244.16297-6-pbonzini@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* coroutine-lock: place CoMutex before CoQueue in headerPaolo Bonzini2017-02-211-45/+44Star
| | | | | | | | | | This will avoid forward references in the next patch. It is also more logical because CoQueue is not anymore the basic primitive. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com> Message-id: 20170213181244.16297-5-pbonzini@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* coroutine-lock: add limited spinning to CoMutexPaolo Bonzini2017-02-211-0/+5
| | | | | | | | | | | | | | | | | Running a very small critical section on pthread_mutex_t and CoMutex shows that pthread_mutex_t is much faster because it doesn't actually go to sleep. What happens is that the critical section is shorter than the latency of entering the kernel and thus FUTEX_WAIT always fails. With CoMutex there is no such latency but you still want to avoid wait and wakeup. So introduce it artificially. This only works with one waiters; because CoMutex is fair, it will always have more waits and wakeups than a pthread_mutex_t. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com> Message-id: 20170213181244.16297-3-pbonzini@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* coroutine-lock: make CoMutex thread-safePaolo Bonzini2017-02-211-2/+15
| | | | | | | | | | | | | | | This uses the lock-free mutex described in the paper '"Blocking without Locking", or LFTHREADS: A lock-free thread library' by Gidenstam and Papatriantafilou. The same technique is used in OSv, and in fact the code is essentially a conversion to C of OSv's code. [Added missing coroutine_fn in tests/test-aio-multithread.c. --Stefan] Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com> Message-id: 20170213181244.16297-2-pbonzini@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* coroutine: Introduce qemu_coroutine_enter_if_inactive()Kevin Wolf2017-01-091-0/+6
| | | | | | | | | | | In the context of asynchronous work, if we have a worker coroutine that didn't yield, the parent coroutine cannot be reentered because it hasn't yielded yet. In this case we don't even have to reenter the parent because it will see that the work is already done and won't even yield. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Alberto Garcia <berto@igalia.com>
* coroutine: add qemu_coroutine_entered() functionStefan Hajnoczi2016-09-281-0/+13
| | | | | | | | | See the doc comments for a description of this new coroutine API. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com> Message-id: 1474989516-18255-2-git-send-email-stefanha@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* coroutine: Let CoMutex remember who holds itKevin Wolf2016-09-051-0/+1
| | | | | | | | | | | In cases of deadlocks, knowing who holds a given CoMutex is really helpful for debugging. Keeping the information around doesn't cost much and allows us to add another assertion to keep the code correct, so let's just add it. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
* coroutine: move entry argument to qemu_coroutine_createPaolo Bonzini2016-07-131-5/+3Star
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In practice the entry argument is always known at creation time, and it is confusing that sometimes qemu_coroutine_enter is used with a non-NULL argument to re-enter a coroutine (this happens in block/sheepdog.c and tests/test-coroutine.c). So pass the opaque value at creation time, for consistency with e.g. aio_bh_new. Mostly done with the following semantic patch: @ entry1 @ expression entry, arg, co; @@ - co = qemu_coroutine_create(entry); + co = qemu_coroutine_create(entry, arg); ... - qemu_coroutine_enter(co, arg); + qemu_coroutine_enter(co); @ entry2 @ expression entry, arg; identifier co; @@ - Coroutine *co = qemu_coroutine_create(entry); + Coroutine *co = qemu_coroutine_create(entry, arg); ... - qemu_coroutine_enter(co, arg); + qemu_coroutine_enter(co); @ entry3 @ expression entry, arg; @@ - qemu_coroutine_enter(qemu_coroutine_create(entry), arg); + qemu_coroutine_enter(qemu_coroutine_create(entry, arg)); @ reentry @ expression co; @@ - qemu_coroutine_enter(co, NULL); + qemu_coroutine_enter(co); except for the aforementioned few places where the semantic patch stumbled (as expected) and for test_co_queue, which would otherwise produce an uninitialized variable warning. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
* coroutine: use QSIMPLEQ instead of QTAILQPaolo Bonzini2016-07-131-1/+1
| | | | | | | | | | | CoQueue do not need to remove any element but the head of the list; processing is always strictly FIFO. Therefore, the simpler singly-linked QSIMPLEQ can be used instead. Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
* Use scripts/clean-includes to drop redundant qemu/typedefs.hMarkus Armbruster2016-03-221-1/+0Star
| | | | | | | | | | | | Re-run scripts/clean-includes to apply the previous commit's corrections and updates. Besides redundant qemu/typedefs.h, this only finds a redundant config-host.h include in ui/egl-helpers.c. No idea how that escaped the previous runs. Some manual whitespace trimming around dropped includes squashed in. Signed-off-by: Markus Armbruster <armbru@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
* include: Clean up includesPeter Maydell2016-02-231-1/+0Star
| | | | | | | | | | | | | | Clean up includes so that osdep.h is included first and headers which it implies are not included manually. This commit was created with scripts/clean-includes. NB: If this commit breaks compilation for your out-of-tree patchseries or fork, then you need to make sure you add #include "qemu/osdep.h" to any new .c files that you have. Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Eric Blake <eblake@redhat.com>
* coroutine: move into libqemuutil.a libraryDaniel P. Berrange2015-10-201-0/+219
The coroutine files are currently referenced by the block-obj-y variable. The coroutine functionality though is already used by more than just the block code. eg migration code uses coroutine yield. In the future the I/O channel code will also use the coroutine yield functionality. Since the coroutine code is nicely self-contained it can be easily built as part of the libqemuutil.a library, making it widely available. The headers are also moved into include/qemu, instead of the include/block directory, since they are now part of the util codebase, and the impl was never in the block/ directory either. Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
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