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* qemu/atomic.h: rename atomic_ to qatomic_Stefan Hajnoczi2020-09-231-26/+26
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | clang's C11 atomic_fetch_*() functions only take a C11 atomic type pointer argument. QEMU uses direct types (int, etc) and this causes a compiler error when a QEMU code calls these functions in a source file that also included <stdatomic.h> via a system header file: $ CC=clang CXX=clang++ ./configure ... && make ../util/async.c:79:17: error: address argument to atomic operation must be a pointer to _Atomic type ('unsigned int *' invalid) Avoid using atomic_*() names in QEMU's atomic.h since that namespace is used by <stdatomic.h>. Prefix QEMU's APIs with 'q' so that atomic.h and <stdatomic.h> can co-exist. I checked /usr/include on my machine and searched GitHub for existing "qatomic_" users but there seem to be none. This patch was generated using: $ git grep -h -o '\<atomic\(64\)\?_[a-z0-9_]\+' include/qemu/atomic.h | \ sort -u >/tmp/changed_identifiers $ for identifier in $(</tmp/changed_identifiers); do sed -i "s%\<$identifier\>%q$identifier%g" \ $(git grep -I -l "\<$identifier\>") done I manually fixed line-wrap issues and misaligned rST tables. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> Acked-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20200923105646.47864-1-stefanha@redhat.com>
* tests: Do not use "\n" in g_test_message() stringsThomas Huth2019-03-071-4/+4
| | | | | | | | g_test_message() takes care of the newline on its own, so we should not use \n in the strings here. Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Thomas Huth <thuth@redhat.com>
* Include qapi/error.h exactly where neededMarkus Armbruster2018-02-091-1/+0Star
| | | | | | | | | | | | | | This cleanup makes the number of objects depending on qapi/error.h drop from 1910 (out of 4743) to 1612 in my "build everything" tree. While there, separate #include from file comment with a blank line, and drop a useless comment on why qemu/osdep.h is included first. Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org> Signed-off-by: Markus Armbruster <armbru@redhat.com> Message-Id: <20180201111846.21846-5-armbru@redhat.com> [Semantic conflict with commit 34e304e975 resolved, OSX breakage fixed]
* misc: remove headers implicitly includedPhilippe Mathieu-Daudé2017-12-181-1/+0Star
| | | | | | | | | | applied using ./scripts/clean-includes Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org> Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Ben Warren <ben@skyportsystems.com> Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
* tests-aio-multithread: fix /aio/multi/schedule race conditionStefan Hajnoczi2017-11-081-3/+2Star
| | | | | | | | | | | | | | | | | | | | | | test_multi_co_schedule_entry() set to_schedule[id] in the final loop iteration before terminating the coroutine. There is a race condition where the main thread attempts to enter the terminating or terminated coroutine when signalling coroutines to stop: atomic_mb_set(&now_stopping, true); for (i = 0; i < NUM_CONTEXTS; i++) { ctx_run(i, finish_cb, NULL); <--- enters dead coroutine! to_schedule[i] = NULL; } Make sure only to set to_schedule[id] if this coroutine really needs to be scheduled! Reported-by: "R.Nageswara Sastry" <nasastry@in.ibm.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Message-id: 20171106190233.1175-1-stefanha@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* cpus: define QEMUTimerListNotifyCB for QEMU system emulationPaolo Bonzini2017-03-141-1/+1
| | | | | | | | There is no change for now, because the callback just invokes qemu_notify_event. Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
* tests-aio-multithread: use atomic_read properlyPaolo Bonzini2017-02-271-2/+2
| | | | | | | | | | | | nodes[id].next is written by other threads. If atomic_read is not used (matching atomic_set in mcs_mutex_lock!) the compiler can optimize the whole "if" away! Reported-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Tested-by: Greg Kurz <groug@kaod.org> Message-id: 20170227111726.9237-1-pbonzini@redhat.com Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
* test-aio-multithread: add performance comparison with thread-based mutexesPaolo Bonzini2017-02-211-0/+164
| | | | | | | | | | | | | | | Add two implementations of the same benchmark as the previous patch, but using pthreads. One uses a normal QemuMutex, the other is Linux only and implements a fair mutex based on MCS locks and futexes. This shows that the slower performance of the 5-thread case is due to the fairness of CoMutex, rather than to coroutines. If fairness does not matter, as is the case with two threads, CoMutex can actually be faster than pthreads. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com> Message-id: 20170213181244.16297-4-pbonzini@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* coroutine-lock: make CoMutex thread-safePaolo Bonzini2017-02-211-0/+86
| | | | | | | | | | | | | | | 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>
* aio: introduce aio_co_schedule and aio_co_wakePaolo Bonzini2017-02-211-0/+213
aio_co_wake provides the infrastructure to start a coroutine on a "home" AioContext. It will be used by CoMutex and CoQueue, so that coroutines don't jump from one context to another when they go to sleep on a mutex or waitqueue. However, it can also be used as a more efficient alternative to one-shot bottom halves, and saves the effort of tracking which AioContext a coroutine is running on. aio_co_schedule is the part of aio_co_wake that starts a coroutine on a remove AioContext, but it is also useful to implement e.g. bdrv_set_aio_context callbacks. The implementation of aio_co_schedule is based on a lock-free multiple-producer, single-consumer queue. The multiple producers use cmpxchg to add to a LIFO stack. The consumer (a per-AioContext bottom half) grabs all items added so far, inverts the list to make it FIFO, and goes through it one item at a time until it's empty. The data structure was inspired by OSv, which uses it in the very code we'll "port" to QEMU for the thread-safe CoMutex. Most of the new code is really tests. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com> Message-id: 20170213135235.12274-3-pbonzini@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>