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charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Received-SPF: pass client-ip=170.10.133.124; envelope-from=peterx@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Wed, Aug 20, 2025 at 02:43:54PM +0100, Daniel P. Berrangé wrote: > On Wed, Aug 20, 2025 at 09:27:09AM -0400, Peter Xu wrote: > > On Wed, Aug 13, 2025 at 07:48:47PM +0300, Vladimir Sementsov-Ogievskiy wrote: > > > Add a possibility to keep socket non-block status when passing > > > through qio channel. We need this to support migration of open > > > fds through migration channel. > > > > > > Signed-off-by: Vladimir Sementsov-Ogievskiy > > > --- > > > include/io/channel-socket.h | 3 +++ > > > io/channel-socket.c | 16 ++++++++++++---- > > > 2 files changed, 15 insertions(+), 4 deletions(-) > > > > > > diff --git a/include/io/channel-socket.h b/include/io/channel-socket.h > > > index a88cf8b3a9..0a4327d745 100644 > > > --- a/include/io/channel-socket.h > > > +++ b/include/io/channel-socket.h > > > @@ -49,6 +49,7 @@ struct QIOChannelSocket { > > > socklen_t remoteAddrLen; > > > ssize_t zero_copy_queued; > > > ssize_t zero_copy_sent; > > > + bool keep_nonblock; > > > }; > > > > > > > > > @@ -275,4 +276,6 @@ int qio_channel_socket_set_send_buffer(QIOChannelSocket *ioc, > > > size_t size, > > > Error **errp); > > > > > > +void qio_channel_socket_keep_nonblock(QIOChannel *ioc); > > > + > > > #endif /* QIO_CHANNEL_SOCKET_H */ > > > diff --git a/io/channel-socket.c b/io/channel-socket.c > > > index 3b7ca924ff..cd93d7f180 100644 > > > --- a/io/channel-socket.c > > > +++ b/io/channel-socket.c > > > @@ -462,9 +462,16 @@ static void qio_channel_socket_finalize(Object *obj) > > > } > > > > > > > > > +void qio_channel_socket_keep_nonblock(QIOChannel *ioc) > > > +{ > > > + QIOChannelSocket *sioc = QIO_CHANNEL_SOCKET(ioc); > > > + sioc->keep_nonblock = true; > > > +} > > > + > > > + > > > #ifndef WIN32 > > > static void qio_channel_socket_copy_fds(struct msghdr *msg, > > > - int **fds, size_t *nfds) > > > + int **fds, size_t *nfds, bool set_block) > > > { > > > struct cmsghdr *cmsg; > > > > > > @@ -497,8 +504,9 @@ static void qio_channel_socket_copy_fds(struct msghdr *msg, > > > continue; > > > } > > > > > > - /* O_NONBLOCK is preserved across SCM_RIGHTS so reset it */ > > > - qemu_socket_set_block(fd); > > > + if (set_block) { > > > + qemu_socket_set_block(fd); > > > + } > > > > "keep_nonblock" as a feature in iochannel is slightly hard to digest. It > > can also be read as "keep the fd to be always nonblocking". > > > > Is this feature required, or can this also be done in a get() or > > post_load() on the other side to set nonblock to whatever it should be > > (that dest QEMU should be aware of)? > > Either we preserve state of the flag when receiving the FD, > or every QEMU backend that we're receiving FDs on behalf of > needs to reset the flag when migration passes over the FD. > > The latter might actually be a more robust scheme. If we're > migrating across QEMU versions, there is not a strict > guarantee that the new QEMU version's backend will want the > O_NONBLOCK flag in the same state as the old QEMU version. > The code might have been re-written to work in a different > way than previously. Good point. Do you remember why we reset that in the very initial git commit? Thanks, -- Peter Xu