diff options
Diffstat (limited to 'include/qemu/main-loop.h')
| -rw-r--r-- | include/qemu/main-loop.h | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/include/qemu/main-loop.h b/include/qemu/main-loop.h index 8dbc6fcb89..7a4d6a0920 100644 --- a/include/qemu/main-loop.h +++ b/include/qemu/main-loop.h @@ -242,10 +242,52 @@ AioContext *iohandler_get_aio_context(void); * must always be taken outside other locks. This function helps * functions take different paths depending on whether the current * thread is running within the main loop mutex. + * + * This function should never be used in the block layer, because + * unit tests, block layer tools and qemu-storage-daemon do not + * have a BQL. + * Please instead refer to qemu_in_main_thread(). */ bool qemu_mutex_iothread_locked(void); /** + * qemu_in_main_thread: return whether it's possible to safely access + * the global state of the block layer. + * + * Global state of the block layer is not accessible from I/O threads + * or worker threads; only from threads that "own" the default + * AioContext that qemu_get_aio_context() returns. For tests, block + * layer tools and qemu-storage-daemon there is a designated thread that + * runs the event loop for qemu_get_aio_context(), and that is the + * main thread. + * + * For emulators, however, any thread that holds the BQL can act + * as the block layer main thread; this will be any of the actual + * main thread, the vCPU threads or the RCU thread. + * + * For clarity, do not use this function outside the block layer. + */ +bool qemu_in_main_thread(void); + +/* Mark and check that the function is part of the global state API. */ +#define GLOBAL_STATE_CODE() \ + do { \ + assert(qemu_in_main_thread()); \ + } while (0) + +/* Mark and check that the function is part of the I/O API. */ +#define IO_CODE() \ + do { \ + /* nop */ \ + } while (0) + +/* Mark and check that the function is part of the "I/O OR GS" API. */ +#define IO_OR_GS_CODE() \ + do { \ + /* nop */ \ + } while (0) + +/** * qemu_mutex_lock_iothread: Lock the main loop mutex. * * This function locks the main loop mutex. The mutex is taken by |