* [PATCH v4 0/2] migration: check magic value for deciding the mapping of channels
@ 2022-11-23 15:05 manish.mishra
2022-11-23 15:05 ` [PATCH v4 1/2] io: Add support for MSG_PEEK for socket channel manish.mishra
2022-11-23 15:05 ` [PATCH v4 2/2] migration: check magic value for deciding the mapping of channels manish.mishra
0 siblings, 2 replies; 11+ messages in thread
From: manish.mishra @ 2022-11-23 15:05 UTC (permalink / raw)
To: qemu-devel
Cc: berrange, peterx, prerna.saxena, quintela, dgilbert, lsoaresp,
manish.mishra
Current logic assumes that channel connections on the destination side are
always established in the same order as the source and the first one will
always be the main channel followed by the multifid or post-copy
preemption channel. This may not be always true, as even if a channel has a
connection established on the source side it can be in the pending state on
the destination side and a newer connection can be established first.
Basically causing out of order mapping of channels on the destination side.
Currently, all channels except post-copy preempt send a magic number, this
patch uses that magic number to decide the type of channel. This logic is
applicable only for precopy(multifd) live migration, as mentioned, the
post-copy preempt channel does not send any magic number. Also, tls live
migrations already does tls handshake before creating other channels, so
this issue is not possible with tls, hence this logic is avoided for tls
live migrations. This patch uses MSG_PEEK to check the magic number of
channels so that current data/control stream management remains
un-effected.
v2:
TLS does not support MSG_PEEK, so V1 was broken for tls live
migrations. For tls live migration, while initializing main channel
tls handshake is done before we can create other channels, so this
issue is not possible for tls live migrations. In V2 added a check
to avoid checking magic number for tls live migration and fallback
to older method to decide mapping of channels on destination side.
v3:
1. Split change in two patches, io patch for read_peek routines,
migration patch for migration related changes.
2. Add flags to io_readv calls to get extra read flags like
MSG_PEEK.
3. Some other minor fixes.
v4:
1. Removed common *all_eof routines for read peek and added one
specific to live migration.
2. Updated to use qemu_co_sleep_ns instead of qio_channel_yield.
3. Some other minor fixes.
manish.mishra (2):
io: Add support for MSG_PEEK for socket channel
migration: check magic value for deciding the mapping of channels
chardev/char-socket.c | 4 +--
include/io/channel.h | 6 ++++
io/channel-buffer.c | 1 +
io/channel-command.c | 1 +
io/channel-file.c | 1 +
io/channel-null.c | 1 +
io/channel-socket.c | 17 ++++++++++-
io/channel-tls.c | 1 +
io/channel-websock.c | 1 +
io/channel.c | 16 +++++++---
migration/channel-block.c | 1 +
migration/channel.c | 46 +++++++++++++++++++++++++++++
migration/channel.h | 5 ++++
migration/migration.c | 45 ++++++++++++++++++++--------
migration/multifd.c | 12 +++-----
migration/multifd.h | 2 +-
migration/postcopy-ram.c | 5 +---
migration/postcopy-ram.h | 2 +-
scsi/qemu-pr-helper.c | 2 +-
tests/qtest/tpm-emu.c | 2 +-
tests/unit/test-io-channel-socket.c | 1 +
util/vhost-user-server.c | 2 +-
22 files changed, 138 insertions(+), 36 deletions(-)
--
2.22.3
^ permalink raw reply [flat|nested] 11+ messages in thread
* [PATCH v4 1/2] io: Add support for MSG_PEEK for socket channel
2022-11-23 15:05 [PATCH v4 0/2] migration: check magic value for deciding the mapping of channels manish.mishra
@ 2022-11-23 15:05 ` manish.mishra
2022-11-23 15:42 ` Daniel P. Berrangé
2022-11-23 15:05 ` [PATCH v4 2/2] migration: check magic value for deciding the mapping of channels manish.mishra
1 sibling, 1 reply; 11+ messages in thread
From: manish.mishra @ 2022-11-23 15:05 UTC (permalink / raw)
To: qemu-devel
Cc: berrange, peterx, prerna.saxena, quintela, dgilbert, lsoaresp,
manish.mishra
MSG_PEEK reads from the peek of channel, The data is treated as
unread and the next read shall still return this data. This
support is currently added only for socket class. Extra parameter
'flags' is added to io_readv calls to pass extra read flags like
MSG_PEEK.
Suggested-by: Daniel P. Berrangé <berrange@redhat.com
Signed-off-by: manish.mishra <manish.mishra@nutanix.com>
---
chardev/char-socket.c | 4 ++--
include/io/channel.h | 6 ++++++
io/channel-buffer.c | 1 +
io/channel-command.c | 1 +
io/channel-file.c | 1 +
io/channel-null.c | 1 +
io/channel-socket.c | 17 ++++++++++++++++-
io/channel-tls.c | 1 +
io/channel-websock.c | 1 +
io/channel.c | 16 ++++++++++++----
migration/channel-block.c | 1 +
scsi/qemu-pr-helper.c | 2 +-
tests/qtest/tpm-emu.c | 2 +-
tests/unit/test-io-channel-socket.c | 1 +
util/vhost-user-server.c | 2 +-
15 files changed, 47 insertions(+), 10 deletions(-)
diff --git a/chardev/char-socket.c b/chardev/char-socket.c
index 879564aa8a..5afce9a464 100644
--- a/chardev/char-socket.c
+++ b/chardev/char-socket.c
@@ -283,11 +283,11 @@ static ssize_t tcp_chr_recv(Chardev *chr, char *buf, size_t len)
if (qio_channel_has_feature(s->ioc, QIO_CHANNEL_FEATURE_FD_PASS)) {
ret = qio_channel_readv_full(s->ioc, &iov, 1,
&msgfds, &msgfds_num,
- NULL);
+ 0, NULL);
} else {
ret = qio_channel_readv_full(s->ioc, &iov, 1,
NULL, NULL,
- NULL);
+ 0, NULL);
}
if (msgfds_num) {
diff --git a/include/io/channel.h b/include/io/channel.h
index c680ee7480..716235d496 100644
--- a/include/io/channel.h
+++ b/include/io/channel.h
@@ -34,6 +34,8 @@ OBJECT_DECLARE_TYPE(QIOChannel, QIOChannelClass,
#define QIO_CHANNEL_WRITE_FLAG_ZERO_COPY 0x1
+#define QIO_CHANNEL_READ_FLAG_MSG_PEEK 0x1
+
typedef enum QIOChannelFeature QIOChannelFeature;
enum QIOChannelFeature {
@@ -41,6 +43,7 @@ enum QIOChannelFeature {
QIO_CHANNEL_FEATURE_SHUTDOWN,
QIO_CHANNEL_FEATURE_LISTEN,
QIO_CHANNEL_FEATURE_WRITE_ZERO_COPY,
+ QIO_CHANNEL_FEATURE_READ_MSG_PEEK,
};
@@ -114,6 +117,7 @@ struct QIOChannelClass {
size_t niov,
int **fds,
size_t *nfds,
+ int flags,
Error **errp);
int (*io_close)(QIOChannel *ioc,
Error **errp);
@@ -188,6 +192,7 @@ void qio_channel_set_name(QIOChannel *ioc,
* @niov: the length of the @iov array
* @fds: pointer to an array that will received file handles
* @nfds: pointer filled with number of elements in @fds on return
+ * @flags: read flags (QIO_CHANNEL_READ_FLAG_*)
* @errp: pointer to a NULL-initialized error object
*
* Read data from the IO channel, storing it in the
@@ -224,6 +229,7 @@ ssize_t qio_channel_readv_full(QIOChannel *ioc,
size_t niov,
int **fds,
size_t *nfds,
+ int flags,
Error **errp);
diff --git a/io/channel-buffer.c b/io/channel-buffer.c
index bf52011be2..8096180f85 100644
--- a/io/channel-buffer.c
+++ b/io/channel-buffer.c
@@ -54,6 +54,7 @@ static ssize_t qio_channel_buffer_readv(QIOChannel *ioc,
size_t niov,
int **fds,
size_t *nfds,
+ int flags,
Error **errp)
{
QIOChannelBuffer *bioc = QIO_CHANNEL_BUFFER(ioc);
diff --git a/io/channel-command.c b/io/channel-command.c
index 74516252ba..e7edd091af 100644
--- a/io/channel-command.c
+++ b/io/channel-command.c
@@ -203,6 +203,7 @@ static ssize_t qio_channel_command_readv(QIOChannel *ioc,
size_t niov,
int **fds,
size_t *nfds,
+ int flags,
Error **errp)
{
QIOChannelCommand *cioc = QIO_CHANNEL_COMMAND(ioc);
diff --git a/io/channel-file.c b/io/channel-file.c
index b67687c2aa..d76663e6ae 100644
--- a/io/channel-file.c
+++ b/io/channel-file.c
@@ -86,6 +86,7 @@ static ssize_t qio_channel_file_readv(QIOChannel *ioc,
size_t niov,
int **fds,
size_t *nfds,
+ int flags,
Error **errp)
{
QIOChannelFile *fioc = QIO_CHANNEL_FILE(ioc);
diff --git a/io/channel-null.c b/io/channel-null.c
index 75e3781507..4fafdb770d 100644
--- a/io/channel-null.c
+++ b/io/channel-null.c
@@ -60,6 +60,7 @@ qio_channel_null_readv(QIOChannel *ioc,
size_t niov,
int **fds G_GNUC_UNUSED,
size_t *nfds G_GNUC_UNUSED,
+ int flags,
Error **errp)
{
QIOChannelNull *nioc = QIO_CHANNEL_NULL(ioc);
diff --git a/io/channel-socket.c b/io/channel-socket.c
index b76dca9cc1..dfb8cb6c40 100644
--- a/io/channel-socket.c
+++ b/io/channel-socket.c
@@ -173,6 +173,8 @@ int qio_channel_socket_connect_sync(QIOChannelSocket *ioc,
}
#endif
+ qio_channel_set_feature(QIO_CHANNEL(ioc), QIO_CHANNEL_FEATURE_READ_MSG_PEEK);
+
return 0;
}
@@ -406,6 +408,8 @@ qio_channel_socket_accept(QIOChannelSocket *ioc,
}
#endif /* WIN32 */
+ qio_channel_set_feature(QIO_CHANNEL(cioc), QIO_CHANNEL_FEATURE_READ_MSG_PEEK);
+
trace_qio_channel_socket_accept_complete(ioc, cioc, cioc->fd);
return cioc;
@@ -496,6 +500,7 @@ static ssize_t qio_channel_socket_readv(QIOChannel *ioc,
size_t niov,
int **fds,
size_t *nfds,
+ int flags,
Error **errp)
{
QIOChannelSocket *sioc = QIO_CHANNEL_SOCKET(ioc);
@@ -517,6 +522,10 @@ static ssize_t qio_channel_socket_readv(QIOChannel *ioc,
}
+ if (flags & QIO_CHANNEL_READ_FLAG_MSG_PEEK) {
+ sflags |= MSG_PEEK;
+ }
+
retry:
ret = recvmsg(sioc->fd, &msg, sflags);
if (ret < 0) {
@@ -624,11 +633,17 @@ static ssize_t qio_channel_socket_readv(QIOChannel *ioc,
size_t niov,
int **fds,
size_t *nfds,
+ int flags,
Error **errp)
{
QIOChannelSocket *sioc = QIO_CHANNEL_SOCKET(ioc);
ssize_t done = 0;
ssize_t i;
+ int sflags = 0;
+
+ if (flags & QIO_CHANNEL_READ_FLAG_MSG_PEEK) {
+ sflags |= MSG_PEEK;
+ }
for (i = 0; i < niov; i++) {
ssize_t ret;
@@ -636,7 +651,7 @@ static ssize_t qio_channel_socket_readv(QIOChannel *ioc,
ret = recv(sioc->fd,
iov[i].iov_base,
iov[i].iov_len,
- 0);
+ sflags);
if (ret < 0) {
if (errno == EAGAIN) {
if (done) {
diff --git a/io/channel-tls.c b/io/channel-tls.c
index 4ce890a538..c730cb8ec5 100644
--- a/io/channel-tls.c
+++ b/io/channel-tls.c
@@ -260,6 +260,7 @@ static ssize_t qio_channel_tls_readv(QIOChannel *ioc,
size_t niov,
int **fds,
size_t *nfds,
+ int flags,
Error **errp)
{
QIOChannelTLS *tioc = QIO_CHANNEL_TLS(ioc);
diff --git a/io/channel-websock.c b/io/channel-websock.c
index fb4932ade7..a12acc27cf 100644
--- a/io/channel-websock.c
+++ b/io/channel-websock.c
@@ -1081,6 +1081,7 @@ static ssize_t qio_channel_websock_readv(QIOChannel *ioc,
size_t niov,
int **fds,
size_t *nfds,
+ int flags,
Error **errp)
{
QIOChannelWebsock *wioc = QIO_CHANNEL_WEBSOCK(ioc);
diff --git a/io/channel.c b/io/channel.c
index 0640941ac5..a8c7f11649 100644
--- a/io/channel.c
+++ b/io/channel.c
@@ -52,6 +52,7 @@ ssize_t qio_channel_readv_full(QIOChannel *ioc,
size_t niov,
int **fds,
size_t *nfds,
+ int flags,
Error **errp)
{
QIOChannelClass *klass = QIO_CHANNEL_GET_CLASS(ioc);
@@ -63,7 +64,14 @@ ssize_t qio_channel_readv_full(QIOChannel *ioc,
return -1;
}
- return klass->io_readv(ioc, iov, niov, fds, nfds, errp);
+ if ((flags & QIO_CHANNEL_READ_FLAG_MSG_PEEK) &&
+ !qio_channel_has_feature(ioc, QIO_CHANNEL_FEATURE_READ_MSG_PEEK)) {
+ error_setg_errno(errp, EINVAL,
+ "Channel does not support peek read");
+ return -1;
+ }
+
+ return klass->io_readv(ioc, iov, niov, fds, nfds, flags, errp);
}
@@ -146,7 +154,7 @@ int qio_channel_readv_full_all_eof(QIOChannel *ioc,
while ((nlocal_iov > 0) || local_fds) {
ssize_t len;
len = qio_channel_readv_full(ioc, local_iov, nlocal_iov, local_fds,
- local_nfds, errp);
+ local_nfds, 0, errp);
if (len == QIO_CHANNEL_ERR_BLOCK) {
if (qemu_in_coroutine()) {
qio_channel_yield(ioc, G_IO_IN);
@@ -284,7 +292,7 @@ ssize_t qio_channel_readv(QIOChannel *ioc,
size_t niov,
Error **errp)
{
- return qio_channel_readv_full(ioc, iov, niov, NULL, NULL, errp);
+ return qio_channel_readv_full(ioc, iov, niov, NULL, NULL, 0, errp);
}
@@ -303,7 +311,7 @@ ssize_t qio_channel_read(QIOChannel *ioc,
Error **errp)
{
struct iovec iov = { .iov_base = buf, .iov_len = buflen };
- return qio_channel_readv_full(ioc, &iov, 1, NULL, NULL, errp);
+ return qio_channel_readv_full(ioc, &iov, 1, NULL, NULL, 0, errp);
}
diff --git a/migration/channel-block.c b/migration/channel-block.c
index f4ab53acdb..b7374363c3 100644
--- a/migration/channel-block.c
+++ b/migration/channel-block.c
@@ -53,6 +53,7 @@ qio_channel_block_readv(QIOChannel *ioc,
size_t niov,
int **fds,
size_t *nfds,
+ int flags,
Error **errp)
{
QIOChannelBlock *bioc = QIO_CHANNEL_BLOCK(ioc);
diff --git a/scsi/qemu-pr-helper.c b/scsi/qemu-pr-helper.c
index 196b78c00d..199227a556 100644
--- a/scsi/qemu-pr-helper.c
+++ b/scsi/qemu-pr-helper.c
@@ -614,7 +614,7 @@ static int coroutine_fn prh_read(PRHelperClient *client, void *buf, int sz,
iov.iov_base = buf;
iov.iov_len = sz;
n_read = qio_channel_readv_full(QIO_CHANNEL(client->ioc), &iov, 1,
- &fds, &nfds, errp);
+ &fds, &nfds, 0, errp);
if (n_read == QIO_CHANNEL_ERR_BLOCK) {
qio_channel_yield(QIO_CHANNEL(client->ioc), G_IO_IN);
diff --git a/tests/qtest/tpm-emu.c b/tests/qtest/tpm-emu.c
index 2994d1cf42..3cf1acaf7d 100644
--- a/tests/qtest/tpm-emu.c
+++ b/tests/qtest/tpm-emu.c
@@ -106,7 +106,7 @@ void *tpm_emu_ctrl_thread(void *data)
int *pfd = NULL;
size_t nfd = 0;
- qio_channel_readv_full(ioc, &iov, 1, &pfd, &nfd, &error_abort);
+ qio_channel_readv_full(ioc, &iov, 1, &pfd, &nfd, 0, &error_abort);
cmd = be32_to_cpu(cmd);
g_assert_cmpint(cmd, ==, CMD_SET_DATAFD);
g_assert_cmpint(nfd, ==, 1);
diff --git a/tests/unit/test-io-channel-socket.c b/tests/unit/test-io-channel-socket.c
index b36a5d972a..b964bb202d 100644
--- a/tests/unit/test-io-channel-socket.c
+++ b/tests/unit/test-io-channel-socket.c
@@ -460,6 +460,7 @@ static void test_io_channel_unix_fd_pass(void)
G_N_ELEMENTS(iorecv),
&fdrecv,
&nfdrecv,
+ 0,
&error_abort);
g_assert(nfdrecv == G_N_ELEMENTS(fdsend));
diff --git a/util/vhost-user-server.c b/util/vhost-user-server.c
index 232984ace6..145eb17c08 100644
--- a/util/vhost-user-server.c
+++ b/util/vhost-user-server.c
@@ -116,7 +116,7 @@ vu_message_read(VuDev *vu_dev, int conn_fd, VhostUserMsg *vmsg)
* qio_channel_readv_full may have short reads, keeping calling it
* until getting VHOST_USER_HDR_SIZE or 0 bytes in total
*/
- rc = qio_channel_readv_full(ioc, &iov, 1, &fds, &nfds, &local_err);
+ rc = qio_channel_readv_full(ioc, &iov, 1, &fds, &nfds, 0, &local_err);
if (rc < 0) {
if (rc == QIO_CHANNEL_ERR_BLOCK) {
assert(local_err == NULL);
--
2.22.3
^ permalink raw reply related [flat|nested] 11+ messages in thread
* [PATCH v4 2/2] migration: check magic value for deciding the mapping of channels
2022-11-23 15:05 [PATCH v4 0/2] migration: check magic value for deciding the mapping of channels manish.mishra
2022-11-23 15:05 ` [PATCH v4 1/2] io: Add support for MSG_PEEK for socket channel manish.mishra
@ 2022-11-23 15:05 ` manish.mishra
2022-11-23 15:52 ` Peter Xu
2022-11-23 15:58 ` Daniel P. Berrangé
1 sibling, 2 replies; 11+ messages in thread
From: manish.mishra @ 2022-11-23 15:05 UTC (permalink / raw)
To: qemu-devel
Cc: berrange, peterx, prerna.saxena, quintela, dgilbert, lsoaresp,
manish.mishra
Current logic assumes that channel connections on the destination side are
always established in the same order as the source and the first one will
always be the main channel followed by the multifid or post-copy
preemption channel. This may not be always true, as even if a channel has a
connection established on the source side it can be in the pending state on
the destination side and a newer connection can be established first.
Basically causing out of order mapping of channels on the destination side.
Currently, all channels except post-copy preempt send a magic number, this
patch uses that magic number to decide the type of channel. This logic is
applicable only for precopy(multifd) live migration, as mentioned, the
post-copy preempt channel does not send any magic number. Also, tls live
migrations already does tls handshake before creating other channels, so
this issue is not possible with tls, hence this logic is avoided for tls
live migrations. This patch uses read peek to check the magic number of
channels so that current data/control stream management remains
un-effected.
Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.co
Suggested-by: Daniel P. Berrangé <berrange@redhat.com
Signed-off-by: manish.mishra <manish.mishra@nutanix.com>
---
migration/channel.c | 46 ++++++++++++++++++++++++++++++++++++++++
migration/channel.h | 5 +++++
migration/migration.c | 45 ++++++++++++++++++++++++++++-----------
migration/multifd.c | 12 ++++-------
migration/multifd.h | 2 +-
migration/postcopy-ram.c | 5 +----
migration/postcopy-ram.h | 2 +-
7 files changed, 91 insertions(+), 26 deletions(-)
diff --git a/migration/channel.c b/migration/channel.c
index 1b0815039f..a4600f52c5 100644
--- a/migration/channel.c
+++ b/migration/channel.c
@@ -92,3 +92,49 @@ void migration_channel_connect(MigrationState *s,
migrate_fd_connect(s, error);
error_free(error);
}
+
+
+/**
+ * @migration_channel_read_peek - Read from the peek of migration channel,
+ * without actually removing it from channel buffer.
+ *
+ * @ioc: the channel object
+ * @buf: the memory region to read data into
+ * @buflen: the number of bytes to read in @buf
+ * @errp: pointer to a NULL-initialized error object
+ *
+ * Returns 0 if successful, returns -1 and sets @errp if fails.
+ */
+int migration_channel_read_peek(QIOChannel *ioc,
+ const char *buf,
+ const size_t buflen,
+ Error **errp)
+{
+ ssize_t len = 0;
+ struct iovec iov = { .iov_base = (char *)buf, .iov_len = buflen };
+
+ while (len < buflen) {
+ len = qio_channel_readv_full(ioc, &iov, 1, NULL,
+ NULL, QIO_CHANNEL_READ_FLAG_MSG_PEEK, errp);
+
+ if (len == QIO_CHANNEL_ERR_BLOCK) {
+ if (qemu_in_coroutine()) {
+ /* 1ms sleep. */
+ qemu_co_sleep_ns(QEMU_CLOCK_REALTIME, 1000000);
+ } else {
+ qio_channel_wait(ioc, G_IO_IN);
+ }
+ continue;
+ }
+ if (len == 0) {
+ error_setg(errp,
+ "Unexpected end-of-file on channel");
+ return -1;
+ }
+ if (len < 0) {
+ return -1;
+ }
+ }
+
+ return 0;
+}
diff --git a/migration/channel.h b/migration/channel.h
index 67a461c28a..5bdb8208a7 100644
--- a/migration/channel.h
+++ b/migration/channel.h
@@ -24,4 +24,9 @@ void migration_channel_connect(MigrationState *s,
QIOChannel *ioc,
const char *hostname,
Error *error_in);
+
+int migration_channel_read_peek(QIOChannel *ioc,
+ const char *buf,
+ const size_t buflen,
+ Error **errp);
#endif
diff --git a/migration/migration.c b/migration/migration.c
index f485eea5fb..8509f20a80 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -31,6 +31,7 @@
#include "migration.h"
#include "savevm.h"
#include "qemu-file.h"
+#include "channel.h"
#include "migration/vmstate.h"
#include "block/block.h"
#include "qapi/error.h"
@@ -733,31 +734,51 @@ void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
{
MigrationIncomingState *mis = migration_incoming_get_current();
Error *local_err = NULL;
- bool start_migration;
QEMUFile *f;
+ bool default_channel = true;
+ uint32_t channel_magic = 0;
+ int ret = 0;
- if (!mis->from_src_file) {
- /* The first connection (multifd may have multiple) */
+ if (migrate_use_multifd() && !migrate_postcopy_ram() &&
+ qio_channel_has_feature(ioc, QIO_CHANNEL_FEATURE_READ_MSG_PEEK)) {
+ /*
+ * With multiple channels, it is possible that we receive channels
+ * out of order on destination side, causing incorrect mapping of
+ * source channels on destination side. Check channel MAGIC to
+ * decide type of channel. Please note this is best effort, postcopy
+ * preempt channel does not send any magic number so avoid it for
+ * postcopy live migration. Also tls live migration already does
+ * tls handshake while initializing main channel so with tls this
+ * issue is not possible.
+ */
+ ret = migration_channel_read_peek(ioc, (void *)&channel_magic,
+ sizeof(channel_magic), &local_err);
+
+ if (ret != 0) {
+ error_propagate(errp, local_err);
+ return;
+ }
+
+ default_channel = (channel_magic == cpu_to_be32(QEMU_VM_FILE_MAGIC));
+ } else {
+ default_channel = !mis->from_src_file;
+ }
+
+ if (default_channel) {
f = qemu_file_new_input(ioc);
if (!migration_incoming_setup(f, errp)) {
return;
}
-
- /*
- * Common migration only needs one channel, so we can start
- * right now. Some features need more than one channel, we wait.
- */
- start_migration = !migration_needs_multiple_sockets();
} else {
/* Multiple connections */
assert(migration_needs_multiple_sockets());
if (migrate_use_multifd()) {
- start_migration = multifd_recv_new_channel(ioc, &local_err);
+ multifd_recv_new_channel(ioc, &local_err);
} else {
assert(migrate_postcopy_preempt());
f = qemu_file_new_input(ioc);
- start_migration = postcopy_preempt_new_channel(mis, f);
+ postcopy_preempt_new_channel(mis, f);
}
if (local_err) {
error_propagate(errp, local_err);
@@ -765,7 +786,7 @@ void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
}
}
- if (start_migration) {
+ if (migration_has_all_channels()) {
/* If it's a recovery, we're done */
if (postcopy_try_recover()) {
return;
diff --git a/migration/multifd.c b/migration/multifd.c
index 509bbbe3bf..b54b6e7528 100644
--- a/migration/multifd.c
+++ b/migration/multifd.c
@@ -1228,11 +1228,9 @@ bool multifd_recv_all_channels_created(void)
/*
* Try to receive all multifd channels to get ready for the migration.
- * - Return true and do not set @errp when correctly receiving all channels;
- * - Return false and do not set @errp when correctly receiving the current one;
- * - Return false and set @errp when failing to receive the current channel.
+ * Sets @errp when failing to receive the current channel.
*/
-bool multifd_recv_new_channel(QIOChannel *ioc, Error **errp)
+void multifd_recv_new_channel(QIOChannel *ioc, Error **errp)
{
MultiFDRecvParams *p;
Error *local_err = NULL;
@@ -1245,7 +1243,7 @@ bool multifd_recv_new_channel(QIOChannel *ioc, Error **errp)
"failed to receive packet"
" via multifd channel %d: ",
qatomic_read(&multifd_recv_state->count));
- return false;
+ return;
}
trace_multifd_recv_new_channel(id);
@@ -1255,7 +1253,7 @@ bool multifd_recv_new_channel(QIOChannel *ioc, Error **errp)
id);
multifd_recv_terminate_threads(local_err);
error_propagate(errp, local_err);
- return false;
+ return;
}
p->c = ioc;
object_ref(OBJECT(ioc));
@@ -1266,6 +1264,4 @@ bool multifd_recv_new_channel(QIOChannel *ioc, Error **errp)
qemu_thread_create(&p->thread, p->name, multifd_recv_thread, p,
QEMU_THREAD_JOINABLE);
qatomic_inc(&multifd_recv_state->count);
- return qatomic_read(&multifd_recv_state->count) ==
- migrate_multifd_channels();
}
diff --git a/migration/multifd.h b/migration/multifd.h
index 519f498643..913e4ba274 100644
--- a/migration/multifd.h
+++ b/migration/multifd.h
@@ -18,7 +18,7 @@ void multifd_save_cleanup(void);
int multifd_load_setup(Error **errp);
int multifd_load_cleanup(Error **errp);
bool multifd_recv_all_channels_created(void);
-bool multifd_recv_new_channel(QIOChannel *ioc, Error **errp);
+void multifd_recv_new_channel(QIOChannel *ioc, Error **errp);
void multifd_recv_sync_main(void);
int multifd_send_sync_main(QEMUFile *f);
int multifd_queue_page(QEMUFile *f, RAMBlock *block, ram_addr_t offset);
diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
index b9a37ef255..f84f783ab4 100644
--- a/migration/postcopy-ram.c
+++ b/migration/postcopy-ram.c
@@ -1539,7 +1539,7 @@ void postcopy_unregister_shared_ufd(struct PostCopyFD *pcfd)
}
}
-bool postcopy_preempt_new_channel(MigrationIncomingState *mis, QEMUFile *file)
+void postcopy_preempt_new_channel(MigrationIncomingState *mis, QEMUFile *file)
{
/*
* The new loading channel has its own threads, so it needs to be
@@ -1548,9 +1548,6 @@ bool postcopy_preempt_new_channel(MigrationIncomingState *mis, QEMUFile *file)
qemu_file_set_blocking(file, true);
mis->postcopy_qemufile_dst = file;
trace_postcopy_preempt_new_channel();
-
- /* Start the migration immediately */
- return true;
}
/*
diff --git a/migration/postcopy-ram.h b/migration/postcopy-ram.h
index 6147bf7d1d..25881c4127 100644
--- a/migration/postcopy-ram.h
+++ b/migration/postcopy-ram.h
@@ -190,7 +190,7 @@ enum PostcopyChannels {
RAM_CHANNEL_MAX,
};
-bool postcopy_preempt_new_channel(MigrationIncomingState *mis, QEMUFile *file);
+void postcopy_preempt_new_channel(MigrationIncomingState *mis, QEMUFile *file);
int postcopy_preempt_setup(MigrationState *s, Error **errp);
int postcopy_preempt_wait_channel(MigrationState *s);
--
2.22.3
^ permalink raw reply related [flat|nested] 11+ messages in thread
* Re: [PATCH v4 1/2] io: Add support for MSG_PEEK for socket channel
2022-11-23 15:05 ` [PATCH v4 1/2] io: Add support for MSG_PEEK for socket channel manish.mishra
@ 2022-11-23 15:42 ` Daniel P. Berrangé
0 siblings, 0 replies; 11+ messages in thread
From: Daniel P. Berrangé @ 2022-11-23 15:42 UTC (permalink / raw)
To: manish.mishra
Cc: qemu-devel, peterx, prerna.saxena, quintela, dgilbert, lsoaresp
On Wed, Nov 23, 2022 at 03:05:26PM +0000, manish.mishra wrote:
> MSG_PEEK reads from the peek of channel, The data is treated as
> unread and the next read shall still return this data. This
> support is currently added only for socket class. Extra parameter
> 'flags' is added to io_readv calls to pass extra read flags like
> MSG_PEEK.
>
> Suggested-by: Daniel P. Berrangé <berrange@redhat.com
> Signed-off-by: manish.mishra <manish.mishra@nutanix.com>
> ---
> chardev/char-socket.c | 4 ++--
> include/io/channel.h | 6 ++++++
> io/channel-buffer.c | 1 +
> io/channel-command.c | 1 +
> io/channel-file.c | 1 +
> io/channel-null.c | 1 +
> io/channel-socket.c | 17 ++++++++++++++++-
> io/channel-tls.c | 1 +
> io/channel-websock.c | 1 +
> io/channel.c | 16 ++++++++++++----
> migration/channel-block.c | 1 +
> scsi/qemu-pr-helper.c | 2 +-
> tests/qtest/tpm-emu.c | 2 +-
> tests/unit/test-io-channel-socket.c | 1 +
> util/vhost-user-server.c | 2 +-
> 15 files changed, 47 insertions(+), 10 deletions(-)
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
With regards,
Daniel
--
|: https://berrange.com -o- https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org -o- https://fstop138.berrange.com :|
|: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH v4 2/2] migration: check magic value for deciding the mapping of channels
2022-11-23 15:05 ` [PATCH v4 2/2] migration: check magic value for deciding the mapping of channels manish.mishra
@ 2022-11-23 15:52 ` Peter Xu
2022-11-23 15:58 ` manish.mishra
2022-11-23 15:58 ` Daniel P. Berrangé
1 sibling, 1 reply; 11+ messages in thread
From: Peter Xu @ 2022-11-23 15:52 UTC (permalink / raw)
To: manish.mishra
Cc: qemu-devel, berrange, prerna.saxena, quintela, dgilbert, lsoaresp
On Wed, Nov 23, 2022 at 03:05:27PM +0000, manish.mishra wrote:
> +int migration_channel_read_peek(QIOChannel *ioc,
> + const char *buf,
> + const size_t buflen,
> + Error **errp)
> +{
> + ssize_t len = 0;
> + struct iovec iov = { .iov_base = (char *)buf, .iov_len = buflen };
> +
> + while (len < buflen) {
> + len = qio_channel_readv_full(ioc, &iov, 1, NULL,
> + NULL, QIO_CHANNEL_READ_FLAG_MSG_PEEK, errp);
> +
> + if (len == QIO_CHANNEL_ERR_BLOCK) {
This needs to take care of partial len too?
> + if (qemu_in_coroutine()) {
> + /* 1ms sleep. */
> + qemu_co_sleep_ns(QEMU_CLOCK_REALTIME, 1000000);
> + } else {
> + qio_channel_wait(ioc, G_IO_IN);
> + }
> + continue;
> + }
> + if (len == 0) {
> + error_setg(errp,
> + "Unexpected end-of-file on channel");
> + return -1;
> + }
> + if (len < 0) {
> + return -1;
> + }
> + }
> +
> + return 0;
> +}
--
Peter Xu
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH v4 2/2] migration: check magic value for deciding the mapping of channels
2022-11-23 15:52 ` Peter Xu
@ 2022-11-23 15:58 ` manish.mishra
2022-11-23 16:27 ` Peter Xu
0 siblings, 1 reply; 11+ messages in thread
From: manish.mishra @ 2022-11-23 15:58 UTC (permalink / raw)
To: Peter Xu
Cc: qemu-devel, berrange, prerna.saxena, quintela, dgilbert, lsoaresp
On 23/11/22 9:22 pm, Peter Xu wrote:
> On Wed, Nov 23, 2022 at 03:05:27PM +0000, manish.mishra wrote:
>> +int migration_channel_read_peek(QIOChannel *ioc,
>> + const char *buf,
>> + const size_t buflen,
>> + Error **errp)
>> +{
>> + ssize_t len = 0;
>> + struct iovec iov = { .iov_base = (char *)buf, .iov_len = buflen };
>> +
>> + while (len < buflen) {
>> + len = qio_channel_readv_full(ioc, &iov, 1, NULL,
>> + NULL, QIO_CHANNEL_READ_FLAG_MSG_PEEK, errp);
>> +
>> + if (len == QIO_CHANNEL_ERR_BLOCK) {
> This needs to take care of partial len too?
sorry Peter, I did not quite understand it. Can you please give some more details.
>
>> + if (qemu_in_coroutine()) {
>> + /* 1ms sleep. */
>> + qemu_co_sleep_ns(QEMU_CLOCK_REALTIME, 1000000);
>> + } else {
>> + qio_channel_wait(ioc, G_IO_IN);
>> + }
>> + continue;
>> + }
>> + if (len == 0) {
>> + error_setg(errp,
>> + "Unexpected end-of-file on channel");
>> + return -1;
>> + }
>> + if (len < 0) {
>> + return -1;
>> + }
>> + }
>> +
>> + return 0;
>> +}
Thanks
Manish Mishra
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH v4 2/2] migration: check magic value for deciding the mapping of channels
2022-11-23 15:05 ` [PATCH v4 2/2] migration: check magic value for deciding the mapping of channels manish.mishra
2022-11-23 15:52 ` Peter Xu
@ 2022-11-23 15:58 ` Daniel P. Berrangé
2022-11-23 16:04 ` manish.mishra
1 sibling, 1 reply; 11+ messages in thread
From: Daniel P. Berrangé @ 2022-11-23 15:58 UTC (permalink / raw)
To: manish.mishra
Cc: qemu-devel, peterx, prerna.saxena, quintela, dgilbert, lsoaresp
On Wed, Nov 23, 2022 at 03:05:27PM +0000, manish.mishra wrote:
> Current logic assumes that channel connections on the destination side are
> always established in the same order as the source and the first one will
> always be the main channel followed by the multifid or post-copy
> preemption channel. This may not be always true, as even if a channel has a
> connection established on the source side it can be in the pending state on
> the destination side and a newer connection can be established first.
> Basically causing out of order mapping of channels on the destination side.
> Currently, all channels except post-copy preempt send a magic number, this
> patch uses that magic number to decide the type of channel. This logic is
> applicable only for precopy(multifd) live migration, as mentioned, the
> post-copy preempt channel does not send any magic number. Also, tls live
> migrations already does tls handshake before creating other channels, so
> this issue is not possible with tls, hence this logic is avoided for tls
> live migrations. This patch uses read peek to check the magic number of
> channels so that current data/control stream management remains
> un-effected.
>
> Reviewed-by: Peter Xu <peterx@redhat.com>
> Reviewed-by: Daniel P. Berrangé <berrange@redhat.co
> Suggested-by: Daniel P. Berrangé <berrange@redhat.com
> Signed-off-by: manish.mishra <manish.mishra@nutanix.com>
> ---
> migration/channel.c | 46 ++++++++++++++++++++++++++++++++++++++++
> migration/channel.h | 5 +++++
> migration/migration.c | 45 ++++++++++++++++++++++++++++-----------
> migration/multifd.c | 12 ++++-------
> migration/multifd.h | 2 +-
> migration/postcopy-ram.c | 5 +----
> migration/postcopy-ram.h | 2 +-
> 7 files changed, 91 insertions(+), 26 deletions(-)
>
> diff --git a/migration/channel.c b/migration/channel.c
> index 1b0815039f..a4600f52c5 100644
> --- a/migration/channel.c
> +++ b/migration/channel.c
> @@ -92,3 +92,49 @@ void migration_channel_connect(MigrationState *s,
> migrate_fd_connect(s, error);
> error_free(error);
> }
> +
> +
> +/**
> + * @migration_channel_read_peek - Read from the peek of migration channel,
> + * without actually removing it from channel buffer.
> + *
> + * @ioc: the channel object
> + * @buf: the memory region to read data into
> + * @buflen: the number of bytes to read in @buf
> + * @errp: pointer to a NULL-initialized error object
> + *
> + * Returns 0 if successful, returns -1 and sets @errp if fails.
> + */
> +int migration_channel_read_peek(QIOChannel *ioc,
> + const char *buf,
> + const size_t buflen,
> + Error **errp)
> +{
> + ssize_t len = 0;
> + struct iovec iov = { .iov_base = (char *)buf, .iov_len = buflen };
> +
> + while (len < buflen) {
> + len = qio_channel_readv_full(ioc, &iov, 1, NULL,
> + NULL, QIO_CHANNEL_READ_FLAG_MSG_PEEK, errp);
> +
> + if (len == QIO_CHANNEL_ERR_BLOCK) {
> + if (qemu_in_coroutine()) {
> + /* 1ms sleep. */
> + qemu_co_sleep_ns(QEMU_CLOCK_REALTIME, 1000000);
> + } else {
> + qio_channel_wait(ioc, G_IO_IN);
> + }
> + continue;
> + }
> + if (len == 0) {
> + error_setg(errp,
> + "Unexpected end-of-file on channel");
> + return -1;
> + }
> + if (len < 0) {
> + return -1;
> + }
> + }
This busy waits when len > 0 and < buflen
With regards,
Daniel
--
|: https://berrange.com -o- https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org -o- https://fstop138.berrange.com :|
|: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH v4 2/2] migration: check magic value for deciding the mapping of channels
2022-11-23 15:58 ` Daniel P. Berrangé
@ 2022-11-23 16:04 ` manish.mishra
2022-11-23 16:19 ` Daniel P. Berrangé
0 siblings, 1 reply; 11+ messages in thread
From: manish.mishra @ 2022-11-23 16:04 UTC (permalink / raw)
To: Daniel P. Berrangé
Cc: qemu-devel, peterx, prerna.saxena, quintela, dgilbert, lsoaresp
On 23/11/22 9:28 pm, Daniel P. Berrangé wrote:
> On Wed, Nov 23, 2022 at 03:05:27PM +0000, manish.mishra wrote:
>> Current logic assumes that channel connections on the destination side are
>> always established in the same order as the source and the first one will
>> always be the main channel followed by the multifid or post-copy
>> preemption channel. This may not be always true, as even if a channel has a
>> connection established on the source side it can be in the pending state on
>> the destination side and a newer connection can be established first.
>> Basically causing out of order mapping of channels on the destination side.
>> Currently, all channels except post-copy preempt send a magic number, this
>> patch uses that magic number to decide the type of channel. This logic is
>> applicable only for precopy(multifd) live migration, as mentioned, the
>> post-copy preempt channel does not send any magic number. Also, tls live
>> migrations already does tls handshake before creating other channels, so
>> this issue is not possible with tls, hence this logic is avoided for tls
>> live migrations. This patch uses read peek to check the magic number of
>> channels so that current data/control stream management remains
>> un-effected.
>>
>> Reviewed-by: Peter Xu <peterx@redhat.com>
>> Reviewed-by: Daniel P. Berrangé <berrange@redhat.co
>> Suggested-by: Daniel P. Berrangé <berrange@redhat.com
>> Signed-off-by: manish.mishra <manish.mishra@nutanix.com>
>> ---
>> migration/channel.c | 46 ++++++++++++++++++++++++++++++++++++++++
>> migration/channel.h | 5 +++++
>> migration/migration.c | 45 ++++++++++++++++++++++++++++-----------
>> migration/multifd.c | 12 ++++-------
>> migration/multifd.h | 2 +-
>> migration/postcopy-ram.c | 5 +----
>> migration/postcopy-ram.h | 2 +-
>> 7 files changed, 91 insertions(+), 26 deletions(-)
>>
>> diff --git a/migration/channel.c b/migration/channel.c
>> index 1b0815039f..a4600f52c5 100644
>> --- a/migration/channel.c
>> +++ b/migration/channel.c
>> @@ -92,3 +92,49 @@ void migration_channel_connect(MigrationState *s,
>> migrate_fd_connect(s, error);
>> error_free(error);
>> }
>> +
>> +
>> +/**
>> + * @migration_channel_read_peek - Read from the peek of migration channel,
>> + * without actually removing it from channel buffer.
>> + *
>> + * @ioc: the channel object
>> + * @buf: the memory region to read data into
>> + * @buflen: the number of bytes to read in @buf
>> + * @errp: pointer to a NULL-initialized error object
>> + *
>> + * Returns 0 if successful, returns -1 and sets @errp if fails.
>> + */
>> +int migration_channel_read_peek(QIOChannel *ioc,
>> + const char *buf,
>> + const size_t buflen,
>> + Error **errp)
>> +{
>> + ssize_t len = 0;
>> + struct iovec iov = { .iov_base = (char *)buf, .iov_len = buflen };
>> +
>> + while (len < buflen) {
>> + len = qio_channel_readv_full(ioc, &iov, 1, NULL,
>> + NULL, QIO_CHANNEL_READ_FLAG_MSG_PEEK, errp);
>> +
>> + if (len == QIO_CHANNEL_ERR_BLOCK) {
>> + if (qemu_in_coroutine()) {
>> + /* 1ms sleep. */
>> + qemu_co_sleep_ns(QEMU_CLOCK_REALTIME, 1000000);
>> + } else {
>> + qio_channel_wait(ioc, G_IO_IN);
>> + }
>> + continue;
>> + }
>> + if (len == 0) {
>> + error_setg(errp,
>> + "Unexpected end-of-file on channel");
>> + return -1;
>> + }
>> + if (len < 0) {
>> + return -1;
>> + }
>> + }
> This busy waits when len > 0 and < buflen
>
>
> With regards,
> Daniel
Sorry, Daniel, may be i misunderstood something from earlier discussions. I thought we discussed we may not prevent it from looping multiple times but we can qemu_co_sleep_ns after every retry to deal with busy wait?
Thanks
Manish Mishra
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH v4 2/2] migration: check magic value for deciding the mapping of channels
2022-11-23 16:04 ` manish.mishra
@ 2022-11-23 16:19 ` Daniel P. Berrangé
0 siblings, 0 replies; 11+ messages in thread
From: Daniel P. Berrangé @ 2022-11-23 16:19 UTC (permalink / raw)
To: manish.mishra
Cc: qemu-devel, peterx, prerna.saxena, quintela, dgilbert, lsoaresp
On Wed, Nov 23, 2022 at 09:34:35PM +0530, manish.mishra wrote:
>
> On 23/11/22 9:28 pm, Daniel P. Berrangé wrote:
> > On Wed, Nov 23, 2022 at 03:05:27PM +0000, manish.mishra wrote:
> > > Current logic assumes that channel connections on the destination side are
> > > always established in the same order as the source and the first one will
> > > always be the main channel followed by the multifid or post-copy
> > > preemption channel. This may not be always true, as even if a channel has a
> > > connection established on the source side it can be in the pending state on
> > > the destination side and a newer connection can be established first.
> > > Basically causing out of order mapping of channels on the destination side.
> > > Currently, all channels except post-copy preempt send a magic number, this
> > > patch uses that magic number to decide the type of channel. This logic is
> > > applicable only for precopy(multifd) live migration, as mentioned, the
> > > post-copy preempt channel does not send any magic number. Also, tls live
> > > migrations already does tls handshake before creating other channels, so
> > > this issue is not possible with tls, hence this logic is avoided for tls
> > > live migrations. This patch uses read peek to check the magic number of
> > > channels so that current data/control stream management remains
> > > un-effected.
> > >
> > > Reviewed-by: Peter Xu <peterx@redhat.com>
> > > Reviewed-by: Daniel P. Berrangé <berrange@redhat.co
> > > Suggested-by: Daniel P. Berrangé <berrange@redhat.com
> > > Signed-off-by: manish.mishra <manish.mishra@nutanix.com>
> > > ---
> > > migration/channel.c | 46 ++++++++++++++++++++++++++++++++++++++++
> > > migration/channel.h | 5 +++++
> > > migration/migration.c | 45 ++++++++++++++++++++++++++++-----------
> > > migration/multifd.c | 12 ++++-------
> > > migration/multifd.h | 2 +-
> > > migration/postcopy-ram.c | 5 +----
> > > migration/postcopy-ram.h | 2 +-
> > > 7 files changed, 91 insertions(+), 26 deletions(-)
> > >
> > > diff --git a/migration/channel.c b/migration/channel.c
> > > index 1b0815039f..a4600f52c5 100644
> > > --- a/migration/channel.c
> > > +++ b/migration/channel.c
> > > @@ -92,3 +92,49 @@ void migration_channel_connect(MigrationState *s,
> > > migrate_fd_connect(s, error);
> > > error_free(error);
> > > }
> > > +
> > > +
> > > +/**
> > > + * @migration_channel_read_peek - Read from the peek of migration channel,
> > > + * without actually removing it from channel buffer.
> > > + *
> > > + * @ioc: the channel object
> > > + * @buf: the memory region to read data into
> > > + * @buflen: the number of bytes to read in @buf
> > > + * @errp: pointer to a NULL-initialized error object
> > > + *
> > > + * Returns 0 if successful, returns -1 and sets @errp if fails.
> > > + */
> > > +int migration_channel_read_peek(QIOChannel *ioc,
> > > + const char *buf,
> > > + const size_t buflen,
> > > + Error **errp)
> > > +{
> > > + ssize_t len = 0;
> > > + struct iovec iov = { .iov_base = (char *)buf, .iov_len = buflen };
> > > +
> > > + while (len < buflen) {
> > > + len = qio_channel_readv_full(ioc, &iov, 1, NULL,
> > > + NULL, QIO_CHANNEL_READ_FLAG_MSG_PEEK, errp);
> > > +
> > > + if (len == QIO_CHANNEL_ERR_BLOCK) {
> > > + if (qemu_in_coroutine()) {
> > > + /* 1ms sleep. */
> > > + qemu_co_sleep_ns(QEMU_CLOCK_REALTIME, 1000000);
> > > + } else {
> > > + qio_channel_wait(ioc, G_IO_IN);
> > > + }
> > > + continue;
> > > + }
> > > + if (len == 0) {
> > > + error_setg(errp,
> > > + "Unexpected end-of-file on channel");
> > > + return -1;
> > > + }
> > > + if (len < 0) {
> > > + return -1;
> > > + }
> > > + }
> > This busy waits when len > 0 and < buflen
> >
> >
> > With regards,
> > Daniel
>
> Sorry, Daniel, may be i misunderstood something from earlier
> discussions. I thought we discussed we may not prevent it from
> looping multiple times but we can qemu_co_sleep_ns after every
> retry to deal with busy wait?
You're only calling qemu_co_sleep_ns when you get ERR_BLOCK
though. That will happen the first time when 0 bytes are
pending. Once 2 bytes arrive and we're waiting for 2 more,
this code will busy wait instead of calling qemu_co_sleep_ns
again, because len==2 in that case.
With regards,
Daniel
--
|: https://berrange.com -o- https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org -o- https://fstop138.berrange.com :|
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^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH v4 2/2] migration: check magic value for deciding the mapping of channels
2022-11-23 15:58 ` manish.mishra
@ 2022-11-23 16:27 ` Peter Xu
2022-11-23 16:33 ` manish.mishra
0 siblings, 1 reply; 11+ messages in thread
From: Peter Xu @ 2022-11-23 16:27 UTC (permalink / raw)
To: manish.mishra
Cc: qemu-devel, berrange, prerna.saxena, quintela, dgilbert, lsoaresp
On Wed, Nov 23, 2022 at 09:28:14PM +0530, manish.mishra wrote:
>
> On 23/11/22 9:22 pm, Peter Xu wrote:
> > On Wed, Nov 23, 2022 at 03:05:27PM +0000, manish.mishra wrote:
> > > +int migration_channel_read_peek(QIOChannel *ioc,
> > > + const char *buf,
> > > + const size_t buflen,
> > > + Error **errp)
> > > +{
> > > + ssize_t len = 0;
> > > + struct iovec iov = { .iov_base = (char *)buf, .iov_len = buflen };
> > > +
> > > + while (len < buflen) {
> > > + len = qio_channel_readv_full(ioc, &iov, 1, NULL,
> > > + NULL, QIO_CHANNEL_READ_FLAG_MSG_PEEK, errp);
> > > +
> > > + if (len == QIO_CHANNEL_ERR_BLOCK) {
> > This needs to take care of partial len too?
>
>
> sorry Peter, I did not quite understand it. Can you please give some more details.
As Daniel pointed out, I think if we peek partially it'll go into a loop.
Since we shouldn't read 0 anyway here, maybe you can directly write it as:
while (true) {
len = read();
if (len <= 0 && len != QIO_CHANNEL_ERR_BLOCK) {
error_setg(...);
return -1;
}
if (len == buflen) {
break;
}
/* For either partial peek or QIO_CHANNEL_ERR_BLOCK, retry with timeout */
sleep();
}
>
> >
> > > + if (qemu_in_coroutine()) {
> > > + /* 1ms sleep. */
> > > + qemu_co_sleep_ns(QEMU_CLOCK_REALTIME, 1000000);
> > > + } else {
> > > + qio_channel_wait(ioc, G_IO_IN);
> > > + }
> > > + continue;
> > > + }
> > > + if (len == 0) {
> > > + error_setg(errp,
> > > + "Unexpected end-of-file on channel");
> > > + return -1;
> > > + }
> > > + if (len < 0) {
> > > + return -1;
> > > + }
> > > + }
> > > +
> > > + return 0;
> > > +}
>
> Thanks
>
> Manish Mishra
>
--
Peter Xu
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH v4 2/2] migration: check magic value for deciding the mapping of channels
2022-11-23 16:27 ` Peter Xu
@ 2022-11-23 16:33 ` manish.mishra
0 siblings, 0 replies; 11+ messages in thread
From: manish.mishra @ 2022-11-23 16:33 UTC (permalink / raw)
To: Peter Xu
Cc: qemu-devel, berrange, prerna.saxena, quintela, dgilbert, lsoaresp
On 23/11/22 9:57 pm, Peter Xu wrote:
> On Wed, Nov 23, 2022 at 09:28:14PM +0530, manish.mishra wrote:
>> On 23/11/22 9:22 pm, Peter Xu wrote:
>>> On Wed, Nov 23, 2022 at 03:05:27PM +0000, manish.mishra wrote:
>>>> +int migration_channel_read_peek(QIOChannel *ioc,
>>>> + const char *buf,
>>>> + const size_t buflen,
>>>> + Error **errp)
>>>> +{
>>>> + ssize_t len = 0;
>>>> + struct iovec iov = { .iov_base = (char *)buf, .iov_len = buflen };
>>>> +
>>>> + while (len < buflen) {
>>>> + len = qio_channel_readv_full(ioc, &iov, 1, NULL,
>>>> + NULL, QIO_CHANNEL_READ_FLAG_MSG_PEEK, errp);
>>>> +
>>>> + if (len == QIO_CHANNEL_ERR_BLOCK) {
>>> This needs to take care of partial len too?
>>
>> sorry Peter, I did not quite understand it. Can you please give some more details.
> As Daniel pointed out, I think if we peek partially it'll go into a loop.
> Since we shouldn't read 0 anyway here, maybe you can directly write it as:
>
> while (true) {
> len = read();
> if (len <= 0 && len != QIO_CHANNEL_ERR_BLOCK) {
> error_setg(...);
> return -1;
> }
> if (len == buflen) {
> break;
> }
> /* For either partial peek or QIO_CHANNEL_ERR_BLOCK, retry with timeout */
> sleep();
> }
Yes, got it, sorry, will update it.
Thanks
Manish Mishra
>>>> + if (qemu_in_coroutine()) {
>>>> + /* 1ms sleep. */
>>>> + qemu_co_sleep_ns(QEMU_CLOCK_REALTIME, 1000000);
>>>> + } else {
>>>> + qio_channel_wait(ioc, G_IO_IN);
>>>> + }
>>>> + continue;
>>>> + }
>>>> + if (len == 0) {
>>>> + error_setg(errp,
>>>> + "Unexpected end-of-file on channel");
>>>> + return -1;
>>>> + }
>>>> + if (len < 0) {
>>>> + return -1;
>>>> + }
>>>> + }
>>>> +
>>>> + return 0;
>>>> +}
>> Thanks
>>
>> Manish Mishra
>>
^ permalink raw reply [flat|nested] 11+ messages in thread
end of thread, other threads:[~2022-11-23 16:33 UTC | newest]
Thread overview: 11+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-11-23 15:05 [PATCH v4 0/2] migration: check magic value for deciding the mapping of channels manish.mishra
2022-11-23 15:05 ` [PATCH v4 1/2] io: Add support for MSG_PEEK for socket channel manish.mishra
2022-11-23 15:42 ` Daniel P. Berrangé
2022-11-23 15:05 ` [PATCH v4 2/2] migration: check magic value for deciding the mapping of channels manish.mishra
2022-11-23 15:52 ` Peter Xu
2022-11-23 15:58 ` manish.mishra
2022-11-23 16:27 ` Peter Xu
2022-11-23 16:33 ` manish.mishra
2022-11-23 15:58 ` Daniel P. Berrangé
2022-11-23 16:04 ` manish.mishra
2022-11-23 16:19 ` Daniel P. Berrangé
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