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f83df00900
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:
|
||
|---|---|---|
| .. | ||
| 9p-local.c | ||
| 9p-local.h | ||
| 9p-posix-acl.c | ||
| 9p-proxy.c | ||
| 9p-proxy.h | ||
| 9p-synth.c | ||
| 9p-synth.h | ||
| 9p-util.c | ||
| 9p-util.h | ||
| 9p-xattr-user.c | ||
| 9p-xattr.c | ||
| 9p-xattr.h | ||
| 9p.c | ||
| 9p.h | ||
| codir.c | ||
| cofile.c | ||
| cofs.c | ||
| coth.c | ||
| coth.h | ||
| coxattr.c | ||
| Kconfig | ||
| meson.build | ||
| trace-events | ||
| trace.h | ||
| virtio-9p-device.c | ||
| virtio-9p.h | ||
| xen-9p-backend.c | ||
| xen-9pfs.h | ||