+/* + * Global state (GS) API. These functions run under the BQL lock. + * + * If a function modifies the graph, it also uses drain and/or + * aio_context_acquire/release to be sure it has unique access. + * aio_context locking is needed together with BQL because of + * the thread-safe I/O API that concurrently runs and accesses + * the graph without the BQL. + * + * It is important to note that not all of these functions are + * necessarily limited to running under the BQL, but they would + * require additional auditing and may small thread-safety changes + * to move them into the I/O API. Often it's not worth doing that + * work since the APIs are only used with the BQL held at the + * moment, so they have been placed in the GS API (for now). + * + * All functions below must use this assertion: + * g_assert(qemu_in_main_thread()); + * to catch when they are accidentally called without the BQL. + */This is comment is duplicated in many places. I suggest explaining it in one place and using references in the other files: /* * Global state (GS) API. These functions run under the BQL lock. * * See include/block/block.h for more information about the GS API. */
Good idea. Should I also do that for I/O, or it's not worth for very few lines?
Thank you, Emanuele
