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| author | Eric Blake <eblake@redhat.com> | 2017-09-05 14:11:12 -0500 |
|---|---|---|
| committer | Eric Blake <eblake@redhat.com> | 2017-09-06 10:10:58 -0500 |
| commit | 9ffb8270205a274a18ee4f8a735e2fccaf957246 (patch) | |
| tree | 6ec3d166399cf431b720d44cf53489cce3187047 /io | |
| parent | 3f5c4076f118072ac7403ca092d63a1766cd5e04 (diff) | |
| download | qemu-9ffb8270205a274a18ee4f8a735e2fccaf957246.tar.gz | |
io: Yield rather than wait when already in coroutine
The new qio_channel_{read,write}{,v}_all functions are documented
as yielding until data is available. When used on a blocking
channel, this yield is done via qio_channel_wait() which spawns
a nested event loop under the hood (so it is that secondary loop
which yields as needed); but if we are already in a coroutine (at
which point QIO_CHANNEL_ERR_BLOCK is only possible if we are a
non-blocking channel), we want to yield the current coroutine
instead of spawning a nested event loop.
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20170905191114.5959-2-eblake@redhat.com>
Acked-by: Daniel P. Berrange <berrange@redhat.com>
[commit message updated]
Signed-off-by: Eric Blake <eblake@redhat.com>
Diffstat (limited to 'io')
| -rw-r--r-- | io/channel.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/io/channel.c b/io/channel.c index 5e8c2f0a91..9e62794cab 100644 --- a/io/channel.c +++ b/io/channel.c @@ -105,7 +105,11 @@ int qio_channel_readv_all(QIOChannel *ioc, ssize_t len; len = qio_channel_readv(ioc, local_iov, nlocal_iov, errp); if (len == QIO_CHANNEL_ERR_BLOCK) { - qio_channel_wait(ioc, G_IO_IN); + if (qemu_in_coroutine()) { + qio_channel_yield(ioc, G_IO_IN); + } else { + qio_channel_wait(ioc, G_IO_IN); + } continue; } else if (len < 0) { goto cleanup; @@ -143,7 +147,11 @@ int qio_channel_writev_all(QIOChannel *ioc, ssize_t len; len = qio_channel_writev(ioc, local_iov, nlocal_iov, errp); if (len == QIO_CHANNEL_ERR_BLOCK) { - qio_channel_wait(ioc, G_IO_OUT); + if (qemu_in_coroutine()) { + qio_channel_yield(ioc, G_IO_OUT); + } else { + qio_channel_wait(ioc, G_IO_OUT); + } continue; } if (len < 0) { |