| Message ID | 1457714282-6981-11-git-send-email-berrange@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
* Daniel P. Berrange (berrange@redhat.com) wrote: > Currently if an application initiates an outgoing migration, > it may or may not, get an error reported back on failure. If > the error occurs synchronously to the 'migrate' command > execution, the client app will see the error message. This > is the case for DNS lookup failures. If the error occurs > asynchronously to the monitor command though, the error > will be thrown away and the client left guessing about > what went wrong. This is the case for failure to connect > to the TCP server (eg due to wrong port, or firewall > rules, or other similar errors). > > In the future we'll be adding more scope for errors to > happen asynchronously with the TLS protocol handshake. > TLS errors are hard to diagnose even when they are well > reported, so discarding errors entirely will make it > impossible to debug TLS connection problems. > > Management apps which do migration are already using > 'query-migrate' / 'info migrate' to check up on progress > of background migration operations and to see their end > status. This is a fine place to also include the error > message when things go wrong. > > This patch thus adds an 'error-desc' field to the > MigrationInfo struct, which will be populated when > the 'status' is set to 'failed': > > (qemu) migrate -d tcp:localhost:9001 > (qemu) info migrate > capabilities: xbzrle: off rdma-pin-all: off auto-converge: off zero-blocks: off compress: off events: off x-postcopy-ram: off > Migration status: failed (Error connecting to socket: Connection refused) > total time: 0 milliseconds > > In the HMP, when doing non-detached migration, it is > also possible to display this error message directly > to the app. > > (qemu) migrate tcp:localhost:9001 > Error connecting to socket: Connection refused > > Or with QMP > > { > "execute": "query-migrate", > "arguments": {} > } > { > "return": { > "status": "failed", > "error-desc": "address resolution failed for myhost:9000: No address associated with hostname" > } > } > > Signed-off-by: Daniel P. Berrange <berrange@redhat.com> > --- > hmp.c | 13 ++++++++++++- > include/migration/migration.h | 5 ++++- > include/qapi/error.h | 2 +- > migration/migration.c | 15 ++++++++++++--- > migration/rdma.c | 10 +++------- > migration/tcp.c | 2 +- > migration/unix.c | 2 +- > qapi-schema.json | 7 ++++++- > trace-events | 2 +- > util/error.c | 2 +- > 10 files changed, 42 insertions(+), 18 deletions(-) > > diff --git a/hmp.c b/hmp.c > index 5b6084a..7126f17 100644 > --- a/hmp.c > +++ b/hmp.c > @@ -34,6 +34,7 @@ > #include "ui/console.h" > #include "block/qapi.h" > #include "qemu-io.h" > +#include "qemu/error-report.h" > > #ifdef CONFIG_SPICE > #include <spice/enums.h> > @@ -167,8 +168,15 @@ void hmp_info_migrate(Monitor *mon, const QDict *qdict) > } > > if (info->has_status) { > - monitor_printf(mon, "Migration status: %s\n", > + monitor_printf(mon, "Migration status: %s", > MigrationStatus_lookup[info->status]); > + if (info->status == MIGRATION_STATUS_FAILED && > + info->has_error_desc) { > + monitor_printf(mon, " (%s)\n", info->error_desc); > + } else { > + monitor_printf(mon, "\n"); > + } > + > monitor_printf(mon, "total time: %" PRIu64 " milliseconds\n", > info->total_time); > if (info->has_expected_downtime) { > @@ -1532,6 +1540,9 @@ static void hmp_migrate_status_cb(void *opaque) > if (status->is_block_migration) { > monitor_printf(status->mon, "\n"); > } > + if (info->has_error_desc) { > + error_report("%s", info->error_desc); > + } > monitor_resume(status->mon); > timer_del(status->timer); > g_free(status); > diff --git a/include/migration/migration.h b/include/migration/migration.h > index e335380..46c1bbe 100644 > --- a/include/migration/migration.h > +++ b/include/migration/migration.h > @@ -171,6 +171,9 @@ struct MigrationState > QSIMPLEQ_HEAD(src_page_requests, MigrationSrcPageRequest) src_page_requests; > /* The RAMBlock used in the last src_page_request */ > RAMBlock *last_req_rb; > + > + /* The last error that occurred */ > + Error *error; Note that's now 'first error', but other than that comment: Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com> When you merge this, what will happen with existing libvirt; at the moment I think something tries to extract the error message out of the qemu log - but I don't think this ends up in any log unless something does the query-migrate/info migrate; will that happen now, or does it mean we lose diagnostics until libvirt learns about it? Dave > }; > > void migrate_set_state(int *state, int old_state, int new_state); > @@ -207,7 +210,7 @@ void rdma_start_outgoing_migration(void *opaque, const char *host_port, Error ** > > void rdma_start_incoming_migration(const char *host_port, Error **errp); > > -void migrate_fd_error(MigrationState *s); > +void migrate_fd_error(MigrationState *s, const Error *error); > > void migrate_fd_connect(MigrationState *s); > > diff --git a/include/qapi/error.h b/include/qapi/error.h > index 02e9dd2..c7e2869 100644 > --- a/include/qapi/error.h > +++ b/include/qapi/error.h > @@ -139,7 +139,7 @@ typedef enum ErrorClass { > /* > * Get @err's human-readable error message. > */ > -const char *error_get_pretty(Error *err); > +const char *error_get_pretty(const Error *err); > > /* > * Get @err's error class. > diff --git a/migration/migration.c b/migration/migration.c > index a4edbe5..6b2e128 100644 > --- a/migration/migration.c > +++ b/migration/migration.c > @@ -691,6 +691,10 @@ MigrationInfo *qmp_query_migrate(Error **errp) > break; > case MIGRATION_STATUS_FAILED: > info->has_status = true; > + if (s->error) { > + info->has_error_desc = true; > + info->error_desc = g_strdup(error_get_pretty(s->error)); > + } > break; > case MIGRATION_STATUS_CANCELLED: > info->has_status = true; > @@ -863,12 +867,15 @@ static void migrate_fd_cleanup(void *opaque) > notifier_list_notify(&migration_state_notifiers, s); > } > > -void migrate_fd_error(MigrationState *s) > +void migrate_fd_error(MigrationState *s, const Error *error) > { > - trace_migrate_fd_error(); > + trace_migrate_fd_error(error ? error_get_pretty(error) : ""); > assert(s->to_dst_file == NULL); > migrate_set_state(&s->state, MIGRATION_STATUS_SETUP, > MIGRATION_STATUS_FAILED); > + if (!s->error) { > + s->error = error_copy(error); > + } > notifier_list_notify(&migration_state_notifiers, s); > } > > @@ -967,6 +974,8 @@ MigrationState *migrate_init(const MigrationParams *params) > s->postcopy_after_devices = false; > s->migration_thread_running = false; > s->last_req_rb = NULL; > + error_free(s->error); > + s->error = NULL; > > migrate_set_state(&s->state, MIGRATION_STATUS_NONE, MIGRATION_STATUS_SETUP); > > @@ -1067,7 +1076,7 @@ void qmp_migrate(const char *uri, bool has_blk, bool blk, > } > > if (local_err) { > - migrate_fd_error(s); > + migrate_fd_error(s, local_err); > error_propagate(errp, local_err); > return; > } > diff --git a/migration/rdma.c b/migration/rdma.c > index 187fc1c..cd33d90 100644 > --- a/migration/rdma.c > +++ b/migration/rdma.c > @@ -3487,16 +3487,14 @@ void rdma_start_outgoing_migration(void *opaque, > const char *host_port, Error **errp) > { > MigrationState *s = opaque; > - Error *local_err = NULL, **temp = &local_err; > - RDMAContext *rdma = qemu_rdma_data_init(host_port, &local_err); > + RDMAContext *rdma = qemu_rdma_data_init(host_port, errp); > int ret = 0; > > if (rdma == NULL) { > - ERROR(temp, "Failed to initialize RDMA data structures! %d", ret); > goto err; > } > > - ret = qemu_rdma_source_init(rdma, &local_err, > + ret = qemu_rdma_source_init(rdma, errp, > s->enabled_capabilities[MIGRATION_CAPABILITY_RDMA_PIN_ALL]); > > if (ret) { > @@ -3504,7 +3502,7 @@ void rdma_start_outgoing_migration(void *opaque, > } > > trace_rdma_start_outgoing_migration_after_rdma_source_init(); > - ret = qemu_rdma_connect(rdma, &local_err); > + ret = qemu_rdma_connect(rdma, errp); > > if (ret) { > goto err; > @@ -3516,7 +3514,5 @@ void rdma_start_outgoing_migration(void *opaque, > migrate_fd_connect(s); > return; > err: > - error_propagate(errp, local_err); > g_free(rdma); > - migrate_fd_error(s); > } > diff --git a/migration/tcp.c b/migration/tcp.c > index e888a4e..48904e0 100644 > --- a/migration/tcp.c > +++ b/migration/tcp.c > @@ -40,7 +40,7 @@ static void tcp_wait_for_connect(int fd, Error *err, void *opaque) > if (fd < 0) { > DPRINTF("migrate connect error: %s\n", error_get_pretty(err)); > s->to_dst_file = NULL; > - migrate_fd_error(s); > + migrate_fd_error(s, err); > } else { > DPRINTF("migrate connect success\n"); > s->to_dst_file = qemu_fopen_socket(fd, "wb"); > diff --git a/migration/unix.c b/migration/unix.c > index d9aac36..b3537fd 100644 > --- a/migration/unix.c > +++ b/migration/unix.c > @@ -40,7 +40,7 @@ static void unix_wait_for_connect(int fd, Error *err, void *opaque) > if (fd < 0) { > DPRINTF("migrate connect error: %s\n", error_get_pretty(err)); > s->to_dst_file = NULL; > - migrate_fd_error(s); > + migrate_fd_error(s, err); > } else { > DPRINTF("migrate connect success\n"); > s->to_dst_file = qemu_fopen_socket(fd, "wb"); > diff --git a/qapi-schema.json b/qapi-schema.json > index 362c9d8..2fd6166 100644 > --- a/qapi-schema.json > +++ b/qapi-schema.json > @@ -484,6 +484,10 @@ > # throttled during auto-converge. This is only present when auto-converge > # has started throttling guest cpus. (Since 2.5) > # > +# @error-desc: #optional the human readable error description string, when > +# @status is 'failed'. Clients should not attempt to parse the > +# error strings. (Since 2.6) > +# > # Since: 0.14.0 > ## > { 'struct': 'MigrationInfo', > @@ -494,7 +498,8 @@ > '*expected-downtime': 'int', > '*downtime': 'int', > '*setup-time': 'int', > - '*x-cpu-throttle-percentage': 'int'} } > + '*x-cpu-throttle-percentage': 'int', > + '*error-desc': 'str'} } > > ## > # @query-migrate > diff --git a/trace-events b/trace-events > index 6fba6cc..8e626ab 100644 > --- a/trace-events > +++ b/trace-events > @@ -1483,7 +1483,7 @@ await_return_path_close_on_source_close(void) "" > await_return_path_close_on_source_joining(void) "" > migrate_set_state(int new_state) "new state %d" > migrate_fd_cleanup(void) "" > -migrate_fd_error(void) "" > +migrate_fd_error(const char *error_desc) "error=%s" > migrate_fd_cancel(void) "" > migrate_handle_rp_req_pages(const char *rbname, size_t start, size_t len) "in %s at %zx len %zx" > migrate_pending(uint64_t size, uint64_t max, uint64_t post, uint64_t nonpost) "pending size %" PRIu64 " max %" PRIu64 " (post=%" PRIu64 " nonpost=%" PRIu64 ")" > diff --git a/util/error.c b/util/error.c > index 471b8b3..f134a6d 100644 > --- a/util/error.c > +++ b/util/error.c > @@ -218,7 +218,7 @@ ErrorClass error_get_class(const Error *err) > return err->err_class; > } > > -const char *error_get_pretty(Error *err) > +const char *error_get_pretty(const Error *err) > { > return err->msg; > } > -- > 2.5.0 > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
On Mon, Mar 14, 2016 at 07:57:25PM +0000, Dr. David Alan Gilbert wrote: > * Daniel P. Berrange (berrange@redhat.com) wrote: > > Currently if an application initiates an outgoing migration, > > it may or may not, get an error reported back on failure. If > > the error occurs synchronously to the 'migrate' command > > execution, the client app will see the error message. This > > is the case for DNS lookup failures. If the error occurs > > asynchronously to the monitor command though, the error > > will be thrown away and the client left guessing about > > what went wrong. This is the case for failure to connect > > to the TCP server (eg due to wrong port, or firewall > > rules, or other similar errors). > > > > In the future we'll be adding more scope for errors to > > happen asynchronously with the TLS protocol handshake. > > TLS errors are hard to diagnose even when they are well > > reported, so discarding errors entirely will make it > > impossible to debug TLS connection problems. > > > > Management apps which do migration are already using > > 'query-migrate' / 'info migrate' to check up on progress > > of background migration operations and to see their end > > status. This is a fine place to also include the error > > message when things go wrong. > > > > This patch thus adds an 'error-desc' field to the > > MigrationInfo struct, which will be populated when > > the 'status' is set to 'failed': > > > > (qemu) migrate -d tcp:localhost:9001 > > (qemu) info migrate > > capabilities: xbzrle: off rdma-pin-all: off auto-converge: off zero-blocks: off compress: off events: off x-postcopy-ram: off > > Migration status: failed (Error connecting to socket: Connection refused) > > total time: 0 milliseconds > > > > In the HMP, when doing non-detached migration, it is > > also possible to display this error message directly > > to the app. > > > > (qemu) migrate tcp:localhost:9001 > > Error connecting to socket: Connection refused > > > > Or with QMP > > > > { > > "execute": "query-migrate", > > "arguments": {} > > } > > { > > "return": { > > "status": "failed", > > "error-desc": "address resolution failed for myhost:9000: No address associated with hostname" > > } > > } > > > > Signed-off-by: Daniel P. Berrange <berrange@redhat.com> > > --- > > hmp.c | 13 ++++++++++++- > > include/migration/migration.h | 5 ++++- > > include/qapi/error.h | 2 +- > > migration/migration.c | 15 ++++++++++++--- > > migration/rdma.c | 10 +++------- > > migration/tcp.c | 2 +- > > migration/unix.c | 2 +- > > qapi-schema.json | 7 ++++++- > > trace-events | 2 +- > > util/error.c | 2 +- > > 10 files changed, 42 insertions(+), 18 deletions(-) > > > > diff --git a/hmp.c b/hmp.c > > index 5b6084a..7126f17 100644 > > --- a/hmp.c > > +++ b/hmp.c > > @@ -34,6 +34,7 @@ > > #include "ui/console.h" > > #include "block/qapi.h" > > #include "qemu-io.h" > > +#include "qemu/error-report.h" > > > > #ifdef CONFIG_SPICE > > #include <spice/enums.h> > > @@ -167,8 +168,15 @@ void hmp_info_migrate(Monitor *mon, const QDict *qdict) > > } > > > > if (info->has_status) { > > - monitor_printf(mon, "Migration status: %s\n", > > + monitor_printf(mon, "Migration status: %s", > > MigrationStatus_lookup[info->status]); > > + if (info->status == MIGRATION_STATUS_FAILED && > > + info->has_error_desc) { > > + monitor_printf(mon, " (%s)\n", info->error_desc); > > + } else { > > + monitor_printf(mon, "\n"); > > + } > > + > > monitor_printf(mon, "total time: %" PRIu64 " milliseconds\n", > > info->total_time); > > if (info->has_expected_downtime) { > > @@ -1532,6 +1540,9 @@ static void hmp_migrate_status_cb(void *opaque) > > if (status->is_block_migration) { > > monitor_printf(status->mon, "\n"); > > } > > + if (info->has_error_desc) { > > + error_report("%s", info->error_desc); > > + } > > monitor_resume(status->mon); > > timer_del(status->timer); > > g_free(status); > > diff --git a/include/migration/migration.h b/include/migration/migration.h > > index e335380..46c1bbe 100644 > > --- a/include/migration/migration.h > > +++ b/include/migration/migration.h > > @@ -171,6 +171,9 @@ struct MigrationState > > QSIMPLEQ_HEAD(src_page_requests, MigrationSrcPageRequest) src_page_requests; > > /* The RAMBlock used in the last src_page_request */ > > RAMBlock *last_req_rb; > > + > > + /* The last error that occurred */ > > + Error *error; > > Note that's now 'first error', but other than that comment: > > Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com> > > When you merge this, what will happen with existing libvirt; at the > moment I think something tries to extract the error message out > of the qemu log - but I don't think this ends up in any log > unless something does the query-migrate/info migrate; will that > happen now, or does it mean we lose diagnostics until libvirt learns > about it? I've not removed any lines which printed to stderr, so libvirt should be no worse off than today. Regards, Daniel
diff --git a/hmp.c b/hmp.c index 5b6084a..7126f17 100644 --- a/hmp.c +++ b/hmp.c @@ -34,6 +34,7 @@ #include "ui/console.h" #include "block/qapi.h" #include "qemu-io.h" +#include "qemu/error-report.h" #ifdef CONFIG_SPICE #include <spice/enums.h> @@ -167,8 +168,15 @@ void hmp_info_migrate(Monitor *mon, const QDict *qdict) } if (info->has_status) { - monitor_printf(mon, "Migration status: %s\n", + monitor_printf(mon, "Migration status: %s", MigrationStatus_lookup[info->status]); + if (info->status == MIGRATION_STATUS_FAILED && + info->has_error_desc) { + monitor_printf(mon, " (%s)\n", info->error_desc); + } else { + monitor_printf(mon, "\n"); + } + monitor_printf(mon, "total time: %" PRIu64 " milliseconds\n", info->total_time); if (info->has_expected_downtime) { @@ -1532,6 +1540,9 @@ static void hmp_migrate_status_cb(void *opaque) if (status->is_block_migration) { monitor_printf(status->mon, "\n"); } + if (info->has_error_desc) { + error_report("%s", info->error_desc); + } monitor_resume(status->mon); timer_del(status->timer); g_free(status); diff --git a/include/migration/migration.h b/include/migration/migration.h index e335380..46c1bbe 100644 --- a/include/migration/migration.h +++ b/include/migration/migration.h @@ -171,6 +171,9 @@ struct MigrationState QSIMPLEQ_HEAD(src_page_requests, MigrationSrcPageRequest) src_page_requests; /* The RAMBlock used in the last src_page_request */ RAMBlock *last_req_rb; + + /* The last error that occurred */ + Error *error; }; void migrate_set_state(int *state, int old_state, int new_state); @@ -207,7 +210,7 @@ void rdma_start_outgoing_migration(void *opaque, const char *host_port, Error ** void rdma_start_incoming_migration(const char *host_port, Error **errp); -void migrate_fd_error(MigrationState *s); +void migrate_fd_error(MigrationState *s, const Error *error); void migrate_fd_connect(MigrationState *s); diff --git a/include/qapi/error.h b/include/qapi/error.h index 02e9dd2..c7e2869 100644 --- a/include/qapi/error.h +++ b/include/qapi/error.h @@ -139,7 +139,7 @@ typedef enum ErrorClass { /* * Get @err's human-readable error message. */ -const char *error_get_pretty(Error *err); +const char *error_get_pretty(const Error *err); /* * Get @err's error class. diff --git a/migration/migration.c b/migration/migration.c index a4edbe5..6b2e128 100644 --- a/migration/migration.c +++ b/migration/migration.c @@ -691,6 +691,10 @@ MigrationInfo *qmp_query_migrate(Error **errp) break; case MIGRATION_STATUS_FAILED: info->has_status = true; + if (s->error) { + info->has_error_desc = true; + info->error_desc = g_strdup(error_get_pretty(s->error)); + } break; case MIGRATION_STATUS_CANCELLED: info->has_status = true; @@ -863,12 +867,15 @@ static void migrate_fd_cleanup(void *opaque) notifier_list_notify(&migration_state_notifiers, s); } -void migrate_fd_error(MigrationState *s) +void migrate_fd_error(MigrationState *s, const Error *error) { - trace_migrate_fd_error(); + trace_migrate_fd_error(error ? error_get_pretty(error) : ""); assert(s->to_dst_file == NULL); migrate_set_state(&s->state, MIGRATION_STATUS_SETUP, MIGRATION_STATUS_FAILED); + if (!s->error) { + s->error = error_copy(error); + } notifier_list_notify(&migration_state_notifiers, s); } @@ -967,6 +974,8 @@ MigrationState *migrate_init(const MigrationParams *params) s->postcopy_after_devices = false; s->migration_thread_running = false; s->last_req_rb = NULL; + error_free(s->error); + s->error = NULL; migrate_set_state(&s->state, MIGRATION_STATUS_NONE, MIGRATION_STATUS_SETUP); @@ -1067,7 +1076,7 @@ void qmp_migrate(const char *uri, bool has_blk, bool blk, } if (local_err) { - migrate_fd_error(s); + migrate_fd_error(s, local_err); error_propagate(errp, local_err); return; } diff --git a/migration/rdma.c b/migration/rdma.c index 187fc1c..cd33d90 100644 --- a/migration/rdma.c +++ b/migration/rdma.c @@ -3487,16 +3487,14 @@ void rdma_start_outgoing_migration(void *opaque, const char *host_port, Error **errp) { MigrationState *s = opaque; - Error *local_err = NULL, **temp = &local_err; - RDMAContext *rdma = qemu_rdma_data_init(host_port, &local_err); + RDMAContext *rdma = qemu_rdma_data_init(host_port, errp); int ret = 0; if (rdma == NULL) { - ERROR(temp, "Failed to initialize RDMA data structures! %d", ret); goto err; } - ret = qemu_rdma_source_init(rdma, &local_err, + ret = qemu_rdma_source_init(rdma, errp, s->enabled_capabilities[MIGRATION_CAPABILITY_RDMA_PIN_ALL]); if (ret) { @@ -3504,7 +3502,7 @@ void rdma_start_outgoing_migration(void *opaque, } trace_rdma_start_outgoing_migration_after_rdma_source_init(); - ret = qemu_rdma_connect(rdma, &local_err); + ret = qemu_rdma_connect(rdma, errp); if (ret) { goto err; @@ -3516,7 +3514,5 @@ void rdma_start_outgoing_migration(void *opaque, migrate_fd_connect(s); return; err: - error_propagate(errp, local_err); g_free(rdma); - migrate_fd_error(s); } diff --git a/migration/tcp.c b/migration/tcp.c index e888a4e..48904e0 100644 --- a/migration/tcp.c +++ b/migration/tcp.c @@ -40,7 +40,7 @@ static void tcp_wait_for_connect(int fd, Error *err, void *opaque) if (fd < 0) { DPRINTF("migrate connect error: %s\n", error_get_pretty(err)); s->to_dst_file = NULL; - migrate_fd_error(s); + migrate_fd_error(s, err); } else { DPRINTF("migrate connect success\n"); s->to_dst_file = qemu_fopen_socket(fd, "wb"); diff --git a/migration/unix.c b/migration/unix.c index d9aac36..b3537fd 100644 --- a/migration/unix.c +++ b/migration/unix.c @@ -40,7 +40,7 @@ static void unix_wait_for_connect(int fd, Error *err, void *opaque) if (fd < 0) { DPRINTF("migrate connect error: %s\n", error_get_pretty(err)); s->to_dst_file = NULL; - migrate_fd_error(s); + migrate_fd_error(s, err); } else { DPRINTF("migrate connect success\n"); s->to_dst_file = qemu_fopen_socket(fd, "wb"); diff --git a/qapi-schema.json b/qapi-schema.json index 362c9d8..2fd6166 100644 --- a/qapi-schema.json +++ b/qapi-schema.json @@ -484,6 +484,10 @@ # throttled during auto-converge. This is only present when auto-converge # has started throttling guest cpus. (Since 2.5) # +# @error-desc: #optional the human readable error description string, when +# @status is 'failed'. Clients should not attempt to parse the +# error strings. (Since 2.6) +# # Since: 0.14.0 ## { 'struct': 'MigrationInfo', @@ -494,7 +498,8 @@ '*expected-downtime': 'int', '*downtime': 'int', '*setup-time': 'int', - '*x-cpu-throttle-percentage': 'int'} } + '*x-cpu-throttle-percentage': 'int', + '*error-desc': 'str'} } ## # @query-migrate diff --git a/trace-events b/trace-events index 6fba6cc..8e626ab 100644 --- a/trace-events +++ b/trace-events @@ -1483,7 +1483,7 @@ await_return_path_close_on_source_close(void) "" await_return_path_close_on_source_joining(void) "" migrate_set_state(int new_state) "new state %d" migrate_fd_cleanup(void) "" -migrate_fd_error(void) "" +migrate_fd_error(const char *error_desc) "error=%s" migrate_fd_cancel(void) "" migrate_handle_rp_req_pages(const char *rbname, size_t start, size_t len) "in %s at %zx len %zx" migrate_pending(uint64_t size, uint64_t max, uint64_t post, uint64_t nonpost) "pending size %" PRIu64 " max %" PRIu64 " (post=%" PRIu64 " nonpost=%" PRIu64 ")" diff --git a/util/error.c b/util/error.c index 471b8b3..f134a6d 100644 --- a/util/error.c +++ b/util/error.c @@ -218,7 +218,7 @@ ErrorClass error_get_class(const Error *err) return err->err_class; } -const char *error_get_pretty(Error *err) +const char *error_get_pretty(const Error *err) { return err->msg; }
Currently if an application initiates an outgoing migration, it may or may not, get an error reported back on failure. If the error occurs synchronously to the 'migrate' command execution, the client app will see the error message. This is the case for DNS lookup failures. If the error occurs asynchronously to the monitor command though, the error will be thrown away and the client left guessing about what went wrong. This is the case for failure to connect to the TCP server (eg due to wrong port, or firewall rules, or other similar errors). In the future we'll be adding more scope for errors to happen asynchronously with the TLS protocol handshake. TLS errors are hard to diagnose even when they are well reported, so discarding errors entirely will make it impossible to debug TLS connection problems. Management apps which do migration are already using 'query-migrate' / 'info migrate' to check up on progress of background migration operations and to see their end status. This is a fine place to also include the error message when things go wrong. This patch thus adds an 'error-desc' field to the MigrationInfo struct, which will be populated when the 'status' is set to 'failed': (qemu) migrate -d tcp:localhost:9001 (qemu) info migrate capabilities: xbzrle: off rdma-pin-all: off auto-converge: off zero-blocks: off compress: off events: off x-postcopy-ram: off Migration status: failed (Error connecting to socket: Connection refused) total time: 0 milliseconds In the HMP, when doing non-detached migration, it is also possible to display this error message directly to the app. (qemu) migrate tcp:localhost:9001 Error connecting to socket: Connection refused Or with QMP { "execute": "query-migrate", "arguments": {} } { "return": { "status": "failed", "error-desc": "address resolution failed for myhost:9000: No address associated with hostname" } } Signed-off-by: Daniel P. Berrange <berrange@redhat.com> --- hmp.c | 13 ++++++++++++- include/migration/migration.h | 5 ++++- include/qapi/error.h | 2 +- migration/migration.c | 15 ++++++++++++--- migration/rdma.c | 10 +++------- migration/tcp.c | 2 +- migration/unix.c | 2 +- qapi-schema.json | 7 ++++++- trace-events | 2 +- util/error.c | 2 +- 10 files changed, 42 insertions(+), 18 deletions(-)