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2014-06-04aio: fix qemu_bh_schedule() bh->ctx race conditionStefan Hajnoczi
qemu_bh_schedule() is supposed to be thread-safe at least the first time it is called. Unfortunately this is not quite true: bh->scheduled = 1; aio_notify(bh->ctx); Since another thread may run the BH callback once it has been scheduled, there is a race condition if the callback frees the BH before aio_notify(bh->ctx) has a chance to run. Reported-by: Stefan Priebe <s.priebe@profihost.ag> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Tested-by: Stefan Priebe <s.priebe@profihost.ag>
2014-03-13aio: add aio_context_acquire() and aio_context_release()Stefan Hajnoczi
It can be useful to run an AioContext from a thread which normally does not "own" the AioContext. For example, request draining can be implemented by acquiring the AioContext and looping aio_poll() until all requests have been completed. The following pattern should work: /* Event loop thread */ while (running) { aio_context_acquire(ctx); aio_poll(ctx, true); aio_context_release(ctx); } /* Another thread */ aio_context_acquire(ctx); bdrv_read(bs, 0x1000, buf, 1); aio_context_release(ctx); This patch implements aio_context_acquire() and aio_context_release(). Note that existing aio_poll() callers do not need to worry about acquiring and releasing - it is only needed when multiple threads will call aio_poll() on the same AioContext. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-08-22aio / timers: aio_ctx_prepare sets timeout from AioContext timersAlex Bligh
Calculate the timeout in aio_ctx_prepare taking into account the timers attached to the AioContext. Alter aio_ctx_check similarly. Signed-off-by: Alex Bligh <alex@alex.org.uk> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-08-22aio / timers: Add a notify callback to QEMUTimerListAlex Bligh
Add a notify pointer to QEMUTimerList so it knows what to notify on a timer change. Signed-off-by: Alex Bligh <alex@alex.org.uk> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-08-22aio / timers: Add QEMUTimerListGroup to AioContextAlex Bligh
Add a QEMUTimerListGroup each AioContext (meaning a QEMUTimerList associated with each clock is added) and delete it when the AioContext is freed. Signed-off-by: Alex Bligh <alex@alex.org.uk> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-08-19aio: drop io_flush argumentStefan Hajnoczi
The .io_flush() handler no longer exists and has no users. Drop the io_flush argument to aio_set_fd_handler() and related functions. The AioFlushEventNotifierHandler and AioFlushHandler typedefs are no longer used and are dropped too. Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-07-19QEMUBH: make AioContext's bh re-entrantLiu Ping Fan
BH will be used outside big lock, so introduce lock to protect between the writers, ie, bh's adders and deleter. The lock only affects the writers and bh's callback does not take this extra lock. Note that for the same AioContext, aio_bh_poll() can not run in parallel yet. Signed-off-by: Liu Ping Fan <pingfank@linux.vnet.ibm.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-03-15aio: add a ThreadPool instance to AioContextStefan Hajnoczi
This patch adds a ThreadPool to AioContext. It's possible that some AioContext instances will never use the ThreadPool, so defer creation until aio_get_thread_pool(). The reason why AioContext should have the ThreadPool is because the ThreadPool is bound to a AioContext instance where the work item's callback function is invoked. It doesn't make sense to keep the ThreadPool pointer anywhere other than AioContext. For example, block/raw-posix.c can get its AioContext's ThreadPool and submit work. Special note about headers: I used struct ThreadPool in aio.h because there is a circular dependency if aio.h includes thread-pool.h. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
2013-02-21aio: convert aio_poll() to g_poll(3)Stefan Hajnoczi
AioHandler already has a GPollFD so we can directly use its events/revents. Add the int pollfds_idx field to AioContext so we can map g_poll(3) results back to AioHandlers. Reuse aio_dispatch() to invoke handlers after g_poll(3). Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Laszlo Ersek <lersek@redhat.com> Message-id: 1361356113-11049-10-git-send-email-stefanha@redhat.com Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2012-12-19misc: move include files to include/qemu/Paolo Bonzini
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2012-12-19block: move include files to include/block/Paolo Bonzini
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2012-12-11aio: Get rid of qemu_aio_flush()Kevin Wolf
There are no remaining users, and new users should probably be using bdrv_drain_all() in the first place. Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-11-12aio: fix aio_ctx_prepare with idle bottom halvesPaolo Bonzini
Commit ed2aec4867f0d5f5de496bb765347b5d0cfe113d changed the return value of aio_ctx_prepare from false to true when only idle bottom halves are available. This broke PC old-style DMA, which uses them. Fix this by making aio_ctx_prepare return true only when non-idle bottom halves are scheduled to run. Reported-by: malc <av1474@comtv.ru> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: malc <av1474@comtv.ru>
2012-10-30aio: clean up now-unused functionsPaolo Bonzini
Some cleanups can now be made, now that the main loop does not anymore need hooks into the bottom half code. Reviewed-by: Anthony Liguori <aliguori@us.ibm.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2012-10-30aio: add aio_notifyPaolo Bonzini
With this change async.c does not rely anymore on any service from main-loop.c, i.e. it is completely self-contained. Reviewed-by: Anthony Liguori <aliguori@us.ibm.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2012-10-30aio: make AioContexts GSourcesPaolo Bonzini
This lets AioContexts be used (optionally) with a glib main loop. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2012-10-30aio: add non-blocking variant of aio_waitPaolo Bonzini
This will be used when polling the GSource attached to an AioContext. Reviewed-by: Anthony Liguori <aliguori@us.ibm.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2012-10-30aio: add I/O handlers to the AioContext interfacePaolo Bonzini
With this patch, I/O handlers (including event notifier handlers) can be attached to a single AioContext. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2012-10-30aio: introduce AioContext, move bottom halves therePaolo Bonzini
Start introducing AioContext, which will let us remove globals from aio.c/async.c, and introduce multiple I/O threads. The bottom half functions now take an additional AioContext argument. A bottom half is created with a specific AioContext that remains the same throughout the lifetime. qemu_bh_new is just a wrapper that uses a global context. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2012-05-01async: Use bool for boolean struct members and remove a holeStefan Weil
Using bool reduces the size of the structure and improves readability. A hole in the structure was removed. Signed-off-by: Stefan Weil <sw@weilnetz.de> Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
2012-04-26main_loop_wait: block indefinitelyStefano Stabellini
- remove qemu_calculate_timeout; - explicitly size timeout to uint32_t; - introduce slirp_update_timeout; - pass NULL as timeout argument to select in case timeout is the maximum value; Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> Acked-by: Paul Brook <paul@codesourcery.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2011-10-21main-loop: create main-loop.hPaolo Bonzini
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2011-09-06async: Allow nested qemu_bh_poll callsKevin Wolf
qemu may segfault when a BH handler first deletes a BH and then (possibly indirectly) calls a nested qemu_bh_poll(). This is because the inner instance frees the BH and deletes it from the list that the outer one processes. This patch deletes BHs only in the outermost qemu_bh_poll instance. Commit 7887f620 already tried to achieve the same, but it assumed that the BH handler would only delete its own BH. With a nested qemu_bh_poll(), this isn't guaranteed, so that commit wasn't enough. Hope this one fixes it for real. Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2011-08-20Use glib memory allocation and free functionsAnthony Liguori
qemu_malloc/qemu_free no longer exist after this commit. Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2011-08-02async: Remove AsyncContextKevin Wolf
The purpose of AsyncContexts was to protect qcow and qcow2 against reentrancy during an emulated bdrv_read/write (which includes a qemu_aio_wait() call and can run AIO callbacks of different requests if it weren't for AsyncContexts). Now both qcow and qcow2 are protected by CoMutexes and AsyncContexts can be removed. Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2011-06-15Allow nested qemu_bh_poll() after BH deletionKevin Wolf
Without this, qemu segfaults when a BH handler first deletes its BH and then calls another function which involves a nested qemu_bh_poll() call. This can be reproduced by generating an I/O error (e.g. with blkdebug) on an IDE device and using rerror/werror=stop to stop the VM. When continuing the VM, qemu segfaults. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
2009-10-27Introduce contexts for asynchronous callbacksKevin Wolf
Add the possibility to use AIO and BHs without allowing foreign callbacks to be run. Basically, you put your own AIOs and BHs in a separate context. For details see the comments in the source. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2009-10-27Split out bottom halvesKevin Wolf
Instead of putting more and more stuff into vl.c, let's have the generic functions that deal with asynchronous callbacks in their own file. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
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