On Tue, Oct 05, 2021 at 10:32:01AM -0400, Emanuele Giuseppe Esposito wrote: > blockjob functions run always under the BQL lock. > > Signed-off-by: Emanuele Giuseppe Esposito <[email protected]> > --- > include/block/blockjob.h | 23 +++++++++++++++++++++++ > 1 file changed, 23 insertions(+) > > diff --git a/include/block/blockjob.h b/include/block/blockjob.h > index d200f33c10..3bf384f8bf 100644 > --- a/include/block/blockjob.h > +++ b/include/block/blockjob.h > @@ -77,6 +77,27 @@ typedef struct BlockJob { > GSList *nodes; > } BlockJob; > > +/* > + * 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. */
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