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(unknown [2a02:6bf:8080:b48::1:39]) by mail-nwsmtp-smtp-corp-main-68.klg.yp-c.yandex.net (smtpcorp/Yandex) with ESMTPSA id vVLKG00Gp4Y0-8uN2PbIv; Wed, 10 Sep 2025 17:31:58 +0300 X-Yandex-Fwd: 1 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yandex-team.ru; s=default; t=1757514718; bh=Yx4NTaUcJuKwbjUw/CSobD8Q4iaCeiBNFfAAK0QsBXo=; h=Message-ID:Date:Cc:Subject:To:From; b=N2LA4Xm25H/9QmtZItl515pTXfMYdzJyJXTS8iXBYIAv542dOkG3MIox/cKAG9d0Q qXgCHlQ4JSugBq0/zTHKeGrvzuw73/Tw/g50nCZfP1eW9pKKyTz5Gr+Fodj0Y5Rd9q v4ZuKLbHGTE+TSU+A8L0413051egYVUfY23eHMTQ= Authentication-Results: mail-nwsmtp-smtp-corp-main-68.klg.yp-c.yandex.net; dkim=pass header.i=@yandex-team.ru From: Vladimir Sementsov-Ogievskiy To: berrange@redhat.com Cc: qemu-devel@nongnu.org, peterx@redhat.com, farosas@suse.de, steven.sistare@oracle.com, vsementsov@yandex-team.ru Subject: [PATCH v3] migration/qemu-file: don't make incoming fds blocking again Date: Wed, 10 Sep 2025 17:31:56 +0300 Message-ID: <20250910143156.1053779-1-vsementsov@yandex-team.ru> X-Mailer: git-send-email 2.48.1 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=178.154.239.200; envelope-from=vsementsov@yandex-team.ru; helo=forwardcorp1d.mail.yandex.net 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, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham 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+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @yandex-team.ru) X-ZM-MESSAGEID: 1757514806605116600 In migration we want to pass fd "as is", not changing its blocking status. The only current user of these fds is CPR state (through VMSTATE_FD), which of-course doesn't want to modify fds on target when source is still running and use these fds. Suggested-by: Daniel P. Berrang=C3=A9 Signed-off-by: Vladimir Sementsov-Ogievskiy Reviewed-by: Daniel P. Berrang=C3=A9 --- v3: RESEND, add qemu-devel to CC, sorry for the noise v2: rework, following Daniel's suggestion to use flag. include/io/channel.h | 1 + io/channel-socket.c | 12 ++++++++---- io/channel.c | 2 +- migration/qemu-file.c | 3 ++- 4 files changed, 12 insertions(+), 6 deletions(-) diff --git a/include/io/channel.h b/include/io/channel.h index 234e5db70d..5394f50768 100644 --- a/include/io/channel.h +++ b/include/io/channel.h @@ -36,6 +36,7 @@ OBJECT_DECLARE_TYPE(QIOChannel, QIOChannelClass, =20 #define QIO_CHANNEL_READ_FLAG_MSG_PEEK 0x1 #define QIO_CHANNEL_READ_FLAG_RELAXED_EOF 0x2 +#define QIO_CHANNEL_READ_FLAG_PRESERVE_BLOCKING 0x4 =20 typedef enum QIOChannelFeature QIOChannelFeature; =20 diff --git a/io/channel-socket.c b/io/channel-socket.c index 3b7ca924ff..2f6e2d84a3 100644 --- a/io/channel-socket.c +++ b/io/channel-socket.c @@ -464,7 +464,8 @@ static void qio_channel_socket_finalize(Object *obj) =20 #ifndef WIN32 static void qio_channel_socket_copy_fds(struct msghdr *msg, - int **fds, size_t *nfds) + int **fds, size_t *nfds, + bool preserve_blocking) { struct cmsghdr *cmsg; =20 @@ -497,8 +498,10 @@ static void qio_channel_socket_copy_fds(struct msghdr = *msg, continue; } =20 - /* O_NONBLOCK is preserved across SCM_RIGHTS so reset it */ - qemu_socket_set_block(fd); + if (!preserve_blocking) { + /* O_NONBLOCK is preserved across SCM_RIGHTS so reset it */ + qemu_socket_set_block(fd); + } =20 #ifndef MSG_CMSG_CLOEXEC qemu_set_cloexec(fd); @@ -556,7 +559,8 @@ static ssize_t qio_channel_socket_readv(QIOChannel *ioc, } =20 if (fds && nfds) { - qio_channel_socket_copy_fds(&msg, fds, nfds); + qio_channel_socket_copy_fds( + &msg, fds, nfds, flags & QIO_CHANNEL_READ_FLAG_PRESERVE_BLOCKI= NG); } =20 return ret; diff --git a/io/channel.c b/io/channel.c index ebd9322765..50d5f7b10b 100644 --- a/io/channel.c +++ b/io/channel.c @@ -58,7 +58,7 @@ ssize_t qio_channel_readv_full(QIOChannel *ioc, { QIOChannelClass *klass =3D QIO_CHANNEL_GET_CLASS(ioc); =20 - if ((fds || nfds) && + if ((fds || nfds || (flags & QIO_CHANNEL_READ_FLAG_PRESERVE_BLOCKING))= && !qio_channel_has_feature(ioc, QIO_CHANNEL_FEATURE_FD_PASS)) { error_setg_errno(errp, EINVAL, "Channel does not support file descriptor passing= "); diff --git a/migration/qemu-file.c b/migration/qemu-file.c index b6ac190034..92c7b5678b 100644 --- a/migration/qemu-file.c +++ b/migration/qemu-file.c @@ -324,6 +324,7 @@ static ssize_t coroutine_mixed_fn qemu_fill_buffer(QEMU= File *f) size_t nfd =3D 0; int **pfds =3D f->can_pass_fd ? &fds : NULL; size_t *pnfd =3D f->can_pass_fd ? &nfd : NULL; + int flags =3D f->can_pass_fd ? QIO_CHANNEL_READ_FLAG_PRESERVE_BLOCKING= : 0; =20 assert(!qemu_file_is_writable(f)); =20 @@ -340,7 +341,7 @@ static ssize_t coroutine_mixed_fn qemu_fill_buffer(QEMU= File *f) =20 do { struct iovec iov =3D { f->buf + pending, IO_BUF_SIZE - pending }; - len =3D qio_channel_readv_full(f->ioc, &iov, 1, pfds, pnfd, 0, + len =3D qio_channel_readv_full(f->ioc, &iov, 1, pfds, pnfd, flags, &local_error); if (len =3D=3D QIO_CHANNEL_ERR_BLOCK) { if (qemu_in_coroutine()) { --=20 2.48.1