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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>
master
Max Reitz 2020-01-22 17:45:28 +01:00
parent b7e9eae98c
commit 78c81a3f10
1 changed files with 13 additions and 1 deletions
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14
block/nbd.c
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@ -70,6 +70,7 @@ typedef struct BDRVNBDState {
CoMutex send_mutex;
CoQueue free_sema;
Coroutine *connection_co;
Coroutine *teardown_co;
QemuCoSleepState *connection_co_sleep_ns_state;
bool drained;
bool wait_drained_end;
@ -203,7 +204,15 @@ static void nbd_teardown_connection(BlockDriverState *bs)
qemu_co_sleep_wake(s->connection_co_sleep_ns_state);
}
}
BDRV_POLL_WHILE(bs, s->connection_co);
if (qemu_in_coroutine()) {
s->teardown_co = qemu_coroutine_self();
/* connection_co resumes us when it terminates */
qemu_coroutine_yield();
s->teardown_co = NULL;
} else {
BDRV_POLL_WHILE(bs, s->connection_co);
}
assert(!s->connection_co);
}
static bool nbd_client_connecting(BDRVNBDState *s)
@ -395,6 +404,9 @@ static coroutine_fn void nbd_connection_entry(void *opaque)
s->ioc = NULL;
}
if (s->teardown_co) {
aio_co_wake(s->teardown_co);
}
aio_wait_kick();
}