tree 87877a95bedeae58e0232c12459608b1bdb4128f
parent 185b43386ad999c80bdc58e41b87f05e5b3e8463
author Paolo Bonzini <pbonzini@redhat.com> 1330935035 +0100
committer Paolo Bonzini <pbonzini@redhat.com> 1334846203 +0200

nbd: do not block in nbd_wr_sync if no data at all is available

Right now, nbd_wr_sync will hang if no data at all is available on the
socket and the other side is not going to provide any.  Relax this by
making it loop only for writes or partial reads.  This fixes a race
where one thread is executing qemu_aio_wait() and another is executing
main_loop_wait().  Then, the select() call in main_loop_wait() can return
stale data and call the "readable" callback with no data in the socket.

Reported-by: Laurent Vivier <laurent@vivier.eu>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>