| Message ID | f83df00900816476cca41bb536e4d532b297d76e.1630582967.git.qemu_oss@crudebyte.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [PULL,1/3] hw/9pfs: avoid 'path' copy in v9fs_walk() | expand |
diff --git a/hw/9pfs/coth.h b/hw/9pfs/coth.h index c51289903d..f83c7dda7b 100644 --- a/hw/9pfs/coth.h +++ b/hw/9pfs/coth.h @@ -51,7 +51,9 @@ */ \ qemu_coroutine_yield(); \ qemu_bh_delete(co_bh); \ - code_block; \ + do { \ + code_block; \ + } while (0); \ /* re-enter back to qemu thread */ \ qemu_coroutine_yield(); \ } while (0)
v9fs_walk() utilizes the v9fs_co_run_in_worker({...}) macro to run the supplied fs driver code block on a background worker thread. When either the 'Twalk' client request was interrupted or if the client requested fid for that 'Twalk' request caused a stat error then that fs driver code block was left by 'break' keyword, with the intention to return from worker thread back to main thread as well: v9fs_co_run_in_worker({ if (v9fs_request_cancelled(pdu)) { err = -EINTR; break; } err = s->ops->lstat(&s->ctx, &dpath, &fidst); if (err < 0) { err = -errno; break; } ... }); However that 'break;' statement also skipped the v9fs_co_run_in_worker() macro's final and mandatory /* re-enter back to qemu thread */ qemu_coroutine_yield(); call and thus caused the rest of v9fs_walk() to be continued being executed on the worker thread instead of main thread, eventually leading to a crash in the transport virtio transport driver. To fix this issue and to prevent the same error from happening again by other users of v9fs_co_run_in_worker() in future, auto wrap the supplied code block into its own do { } while (0); loop inside the 'v9fs_co_run_in_worker' macro definition. Full discussion and backtrace: https://lists.gnu.org/archive/html/qemu-devel/2021-08/msg05209.html https://lists.gnu.org/archive/html/qemu-devel/2021-09/msg00174.html Fixes: 8d6cb100731c4d28535adbf2a3c2d1f29be3fef4 Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com> Cc: qemu-stable@nongnu.org Reviewed-by: Greg Kurz <groug@kaod.org> Message-Id: <E1mLTBg-0002Bh-2D@lizzy.crudebyte.com> --- hw/9pfs/coth.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)