The curl driver has a ugly hack where, if it cannot find an empty CURLState,
it just uses aio_poll to wait for one to be empty. This is probably
buggy when used together with dataplane, and the simplest way to fix it
is to use coroutines instead.
A more immediate effect of the bug however is that it can cause a
recursive call to curl_readv_bh_cb and recursively taking the
BDRVCURLState mutex. This causes a deadlock.
The fix is to unlock the mutex around aio_poll, but for cleanliness we
should also take the mutex around all calls to curl_init_state, even if
reaching the unlock/lock pair is impossible. The same is true for
curl_clean_state.
Reported-by: Kun Wei <kuwei@redhat.com>
Tested-by: Richard W.M. Jones <rjones@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 20170515100059.15795-4-pbonzini@redhat.com
Cc: qemu-stable@nongnu.org
Cc: Jeff Cody <jcody@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Jeff Cody <jcody@redhat.com>
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