| Message ID | 20240627181245.281403-2-kwolf@redhat.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | block/graph-lock: Make WITH_GRAPH_RDLOCK_GUARD() fully checked | expand |
diff --git a/block/block-copy.c b/block/block-copy.c index 7e3b378528..cc618e4561 100644 --- a/block/block-copy.c +++ b/block/block-copy.c @@ -595,7 +595,9 @@ static coroutine_fn int block_copy_task_entry(AioTask *task) if (s->discard_source && ret == 0) { int64_t nbytes = MIN(t->req.offset + t->req.bytes, s->len) - t->req.offset; - bdrv_co_pdiscard(s->source, t->req.offset, nbytes); + WITH_GRAPH_RDLOCK_GUARD() { + bdrv_co_pdiscard(s->source, t->req.offset, nbytes); + } } return ret;
The graph lock needs to be held when calling bdrv_co_pdiscard(). Fix block_copy_task_entry() to take it for the call. WITH_GRAPH_RDLOCK_GUARD() was implemented in a weak way because of limitations in clang's Thread Safety Analysis at the time, so that it only asserts that the lock is held (which allows calling functions that require the lock), but we never deal with the unlocking (so even after the scope of the guard, the compiler assumes that the lock is still held). This is why the compiler didn't catch this locking error. Signed-off-by: Kevin Wolf <kwolf@redhat.com> --- block/block-copy.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)