blockdev: add note that block_job_cb() must be thread-safe

This function is correct but we should document the constraint that everything must be thread-safe. Emitting QMP events and scheduling BHs are both thread-safe so nothing needs to be done here. Signed-off-by: Stefan Hajnoczi <[email protected]> Reviewed-by: Max Reitz <[email protected]> Message-id: [email protected]
mit-pdos · Nov 3, 2014 · 723c5d9 · 723c5d9
1 parent 91fddb0
commit 723c5d9
Showing 1 changed file with 5 additions and 0 deletions.
diff --git a/blockdev.c b/blockdev.c
@@ -1929,6 +1929,11 @@ void qmp_block_resize(bool has_device, const char *device,
 
 static void block_job_cb(void *opaque, int ret)
 {
+    /* Note that this function may be executed from another AioContext besides
+     * the QEMU main loop.  If you need to access anything that assumes the
+     * QEMU global mutex, use a BH or introduce a mutex.
+     */
+
     BlockDriverState *bs = opaque;
     const char *msg = NULL;