block/nbd: Fix hang in .bdrv_close()
When nbd_close() is called from a coroutine, the connection_co never gets to run, and thus nbd_teardown_connection() hangs. This is because aio_co_enter() only puts the connection_co into the main coroutine's wake-up queue, so this main coroutine needs to yield and wait for connection_co to terminate. Suggested-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Max Reitz <mreitz@redhat.com> Message-Id: <20200122164532.178040-2-mreitz@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com> Signed-off-by: Max Reitz <mreitz@redhat.com>
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block/nbd.c
12
block/nbd.c
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@ -70,6 +70,7 @@ typedef struct BDRVNBDState {
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CoMutex send_mutex;
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CoQueue free_sema;
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Coroutine *connection_co;
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Coroutine *teardown_co;
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QemuCoSleepState *connection_co_sleep_ns_state;
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bool drained;
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bool wait_drained_end;
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@ -203,7 +204,15 @@ static void nbd_teardown_connection(BlockDriverState *bs)
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qemu_co_sleep_wake(s->connection_co_sleep_ns_state);
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}
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}
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if (qemu_in_coroutine()) {
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s->teardown_co = qemu_coroutine_self();
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/* connection_co resumes us when it terminates */
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qemu_coroutine_yield();
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s->teardown_co = NULL;
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} else {
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BDRV_POLL_WHILE(bs, s->connection_co);
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}
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assert(!s->connection_co);
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}
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static bool nbd_client_connecting(BDRVNBDState *s)
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@ -395,6 +404,9 @@ static coroutine_fn void nbd_connection_entry(void *opaque)
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s->ioc = NULL;
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}
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if (s->teardown_co) {
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aio_co_wake(s->teardown_co);
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}
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aio_wait_kick();
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}
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