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migration: Refactor error handling in source return path

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rp_state.error was a boolean used to show error happened in return path
thread.  That's not only duplicating error reporting (migrate_set_error),
but also not good enough in that we only do error_report() and set it to
true, we never can keep a history of the exact error and show it in
query-migrate.

To make this better, a few things done:

  - Use error_setg() rather than error_report() across the whole lifecycle
    of return path thread, keeping the error in an Error*.

  - With above, no need to have mark_source_rp_bad(), remove it, alongside
    with rp_state.error itself.

  - Use migrate_set_error() to apply that captured error to the global
    migration object when error occured in this thread.

  - Do the same when detected qemufile error in source return path

We need to re-export qemu_file_get_error_obj() to do the last one.

Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Message-ID: <20231017202633.296756-2-peterx@redhat.com>
This commit is contained in:
Peter Xu 2023-10-17 16:26:29 -04:00 committed by Juan Quintela
parent e7b428d6bc
commit 7aa6070d09
7 changed files with 80 additions and 95 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

121
migration/migration.c
View File

@ -99,7 +99,7 @@ static int migration_maybe_pause(MigrationState *s,
int *current_active_state,
int new_state);
static void migrate_fd_cancel(MigrationState *s);
static int close_return_path_on_source(MigrationState *s);
static bool close_return_path_on_source(MigrationState *s);
static void migration_downtime_start(MigrationState *s)
{
@ -1475,7 +1475,6 @@ int migrate_init(MigrationState *s, Error **errp)
s->to_dst_file = NULL;
s->state = MIGRATION_STATUS_NONE;
s->rp_state.from_dst_file = NULL;
s->rp_state.error = false;
s->mbps = 0.0;
s->pages_per_second = 0.0;
s->downtime = 0;
@ -1883,16 +1882,6 @@ void qmp_migrate_continue(MigrationStatus state, Error **errp)
qemu_sem_post(&s->pause_sem);
}
/* migration thread support */
/*
* Something bad happened to the RP stream, mark an error
* The caller shall print or trace something to indicate why
*/
static void mark_source_rp_bad(MigrationState *s)
{
s->rp_state.error = true;
}
void migration_rp_wait(MigrationState *s)
{
qemu_sem_wait(&s->rp_state.rp_sem);
@ -1923,8 +1912,9 @@ static struct rp_cmd_args {
* We're allowed to send more than requested (e.g. to round to our page size)
* and we don't need to send pages that have already been sent.
*/
static void migrate_handle_rp_req_pages(MigrationState *ms, const char* rbname,
ram_addr_t start, size_t len)
static void
migrate_handle_rp_req_pages(MigrationState *ms, const char* rbname,
ram_addr_t start, size_t len, Error **errp)
{
long our_host_ps = qemu_real_host_page_size();
@ -1936,37 +1926,36 @@ static void migrate_handle_rp_req_pages(MigrationState *ms, const char* rbname,
*/
if (!QEMU_IS_ALIGNED(start, our_host_ps) ||
!QEMU_IS_ALIGNED(len, our_host_ps)) {
error_report("%s: Misaligned page request, start: " RAM_ADDR_FMT
" len: %zd", __func__, start, len);
mark_source_rp_bad(ms);
error_setg(errp, "MIG_RP_MSG_REQ_PAGES: Misaligned page request, start:"
RAM_ADDR_FMT " len: %zd", start, len);
return;
}
if (ram_save_queue_pages(rbname, start, len)) {
mark_source_rp_bad(ms);
}
ram_save_queue_pages(rbname, start, len, errp);
}
static int migrate_handle_rp_recv_bitmap(MigrationState *s, char *block_name)
static int migrate_handle_rp_recv_bitmap(MigrationState *s, char *block_name,
Error **errp)
{
RAMBlock *block = qemu_ram_block_by_name(block_name);
if (!block) {
error_report("%s: invalid block name '%s'", __func__, block_name);
error_setg(errp, "MIG_RP_MSG_RECV_BITMAP has invalid block name '%s'",
block_name);
return -EINVAL;
}
/* Fetch the received bitmap and refresh the dirty bitmap */
return ram_dirty_bitmap_reload(s, block);
return ram_dirty_bitmap_reload(s, block, errp);
}
static int migrate_handle_rp_resume_ack(MigrationState *s, uint32_t value)
static int migrate_handle_rp_resume_ack(MigrationState *s,
uint32_t value, Error **errp)
{
trace_source_return_path_thread_resume_ack(value);
if (value != MIGRATION_RESUME_ACK_VALUE) {
error_report("%s: illegal resume_ack value %"PRIu32,
__func__, value);
error_setg(errp, "illegal resume_ack value %"PRIu32, value);
return -1;
}
@ -2025,48 +2014,46 @@ static void *source_return_path_thread(void *opaque)
uint32_t tmp32, sibling_error;
ram_addr_t start = 0; /* =0 to silence warning */
size_t len = 0, expected_len;
Error *err = NULL;
int res;
trace_source_return_path_thread_entry();
rcu_register_thread();
while (!ms->rp_state.error && !qemu_file_get_error(rp) &&
migration_is_setup_or_active(ms->state)) {
while (migration_is_setup_or_active(ms->state)) {
trace_source_return_path_thread_loop_top();
header_type = qemu_get_be16(rp);
header_len = qemu_get_be16(rp);
if (qemu_file_get_error(rp)) {
mark_source_rp_bad(ms);
qemu_file_get_error_obj(rp, &err);
goto out;
}
if (header_type >= MIG_RP_MSG_MAX ||
header_type == MIG_RP_MSG_INVALID) {
error_report("RP: Received invalid message 0x%04x length 0x%04x",
header_type, header_len);
mark_source_rp_bad(ms);
error_setg(&err, "Received invalid message 0x%04x length 0x%04x",
header_type, header_len);
goto out;
}
if ((rp_cmd_args[header_type].len != -1 &&
header_len != rp_cmd_args[header_type].len) ||
header_len > sizeof(buf)) {
error_report("RP: Received '%s' message (0x%04x) with"
"incorrect length %d expecting %zu",
rp_cmd_args[header_type].name, header_type, header_len,
(size_t)rp_cmd_args[header_type].len);
mark_source_rp_bad(ms);
error_setg(&err, "Received '%s' message (0x%04x) with"
"incorrect length %d expecting %zu",
rp_cmd_args[header_type].name, header_type, header_len,
(size_t)rp_cmd_args[header_type].len);
goto out;
}
/* We know we've got a valid header by this point */
res = qemu_get_buffer(rp, buf, header_len);
if (res != header_len) {
error_report("RP: Failed reading data for message 0x%04x"
" read %d expected %d",
header_type, res, header_len);
mark_source_rp_bad(ms);
error_setg(&err, "Failed reading data for message 0x%04x"
" read %d expected %d",
header_type, res, header_len);
goto out;
}
@ -2076,8 +2063,7 @@ static void *source_return_path_thread(void *opaque)
sibling_error = ldl_be_p(buf);
trace_source_return_path_thread_shut(sibling_error);
if (sibling_error) {
error_report("RP: Sibling indicated error %d", sibling_error);
mark_source_rp_bad(ms);
error_setg(&err, "Sibling indicated error %d", sibling_error);
}
/*
* We'll let the main thread deal with closing the RP
@ -2095,7 +2081,10 @@ static void *source_return_path_thread(void *opaque)
case MIG_RP_MSG_REQ_PAGES:
start = ldq_be_p(buf);
len = ldl_be_p(buf + 8);
migrate_handle_rp_req_pages(ms, NULL, start, len);
migrate_handle_rp_req_pages(ms, NULL, start, len, &err);
if (err) {
goto out;
}
break;
case MIG_RP_MSG_REQ_PAGES_ID:
@ -2110,32 +2099,32 @@ static void *source_return_path_thread(void *opaque)
expected_len += tmp32;
}
if (header_len != expected_len) {
error_report("RP: Req_Page_id with length %d expecting %zd",
header_len, expected_len);
mark_source_rp_bad(ms);
error_setg(&err, "Req_Page_id with length %d expecting %zd",
header_len, expected_len);
goto out;
}
migrate_handle_rp_req_pages(ms, (char *)&buf[13], start, len,
&err);
if (err) {
goto out;
}
migrate_handle_rp_req_pages(ms, (char *)&buf[13], start, len);
break;
case MIG_RP_MSG_RECV_BITMAP:
if (header_len < 1) {
error_report("%s: missing block name", __func__);
mark_source_rp_bad(ms);
error_setg(&err, "MIG_RP_MSG_RECV_BITMAP missing block name");
goto out;
}
/* Format: len (1B) + idstr (<255B). This ends the idstr. */
buf[buf[0] + 1] = '\0';
if (migrate_handle_rp_recv_bitmap(ms, (char *)(buf + 1))) {
mark_source_rp_bad(ms);
if (migrate_handle_rp_recv_bitmap(ms, (char *)(buf + 1), &err)) {
goto out;
}
break;
case MIG_RP_MSG_RESUME_ACK:
tmp32 = ldl_be_p(buf);
if (migrate_handle_rp_resume_ack(ms, tmp32)) {
mark_source_rp_bad(ms);
if (migrate_handle_rp_resume_ack(ms, tmp32, &err)) {
goto out;
}
break;
@ -2151,13 +2140,15 @@ static void *source_return_path_thread(void *opaque)
}
out:
if (qemu_file_get_error(rp)) {
if (err) {
migrate_set_error(ms, err);
error_free(err);
trace_source_return_path_thread_bad_end();
mark_source_rp_bad(ms);
}
trace_source_return_path_thread_end();
rcu_unregister_thread();
return NULL;
}
@ -2179,12 +2170,11 @@ static int open_return_path_on_source(MigrationState *ms)
return 0;
}
static int close_return_path_on_source(MigrationState *ms)
/* Return true if error detected, or false otherwise */
static bool close_return_path_on_source(MigrationState *ms)
{
int ret;
if (!ms->rp_state.rp_thread_created) {
return 0;
return false;
}
trace_migration_return_path_end_before();
@ -2202,18 +2192,13 @@ static int close_return_path_on_source(MigrationState *ms)
}
}
trace_await_return_path_close_on_source_joining();
qemu_thread_join(&ms->rp_state.rp_thread);
ms->rp_state.rp_thread_created = false;
trace_await_return_path_close_on_source_close();
ret = ms->rp_state.error;
ms->rp_state.error = false;
migration_release_dst_files(ms);
trace_migration_return_path_end_after();
trace_migration_return_path_end_after(ret);
return ret;
/* Return path will persist the error in MigrationState when quit */
return migrate_has_error(ms);
}
static inline void

1
migration/migration.h
View File

@ -308,7 +308,6 @@ struct MigrationState {
/* Protected by qemu_file_lock */
QEMUFile *from_dst_file;
QemuThread rp_thread;
bool error;
/*
* We can also check non-zero of rp_thread, but there's no "official"
* way to do this, so this bool makes it slightly more elegant.

2
migration/qemu-file.c
View File

@ -137,7 +137,7 @@ QEMUFile *qemu_file_new_input(QIOChannel *ioc)
*
* If errp is specified, a verbose error message will be copied over.
*/
static int qemu_file_get_error_obj(QEMUFile *f, Error **errp)
int qemu_file_get_error_obj(QEMUFile *f, Error **errp)
{
if (!f->last_error) {
return 0;

1
migration/qemu-file.h
View File

@ -68,6 +68,7 @@ int coroutine_mixed_fn qemu_peek_byte(QEMUFile *f, int offset);
void qemu_file_skip(QEMUFile *f, int size);
int qemu_file_get_error_obj_any(QEMUFile *f1, QEMUFile *f2, Error **errp);
void qemu_file_set_error_obj(QEMUFile *f, int ret, Error *err);
int qemu_file_get_error_obj(QEMUFile *f, Error **errp);
void qemu_file_set_error(QEMUFile *f, int ret);
int qemu_file_shutdown(QEMUFile *f);
QEMUFile *qemu_file_get_return_path(QEMUFile *f);

41
migration/ram.c
View File

@ -1898,7 +1898,8 @@ static void migration_page_queue_free(RAMState *rs)
* @start: starting address from the start of the RAMBlock
* @len: length (in bytes) to send
*/
int ram_save_queue_pages(const char *rbname, ram_addr_t start, ram_addr_t len)
int ram_save_queue_pages(const char *rbname, ram_addr_t start, ram_addr_t len,
Error **errp)
{
RAMBlock *ramblock;
RAMState *rs = ram_state;
@ -1915,7 +1916,7 @@ int ram_save_queue_pages(const char *rbname, ram_addr_t start, ram_addr_t len)
* Shouldn't happen, we can't reuse the last RAMBlock if
* it's the 1st request.
*/
error_report("ram_save_queue_pages no previous block");
error_setg(errp, "MIG_RP_MSG_REQ_PAGES has no previous block");
return -1;
}
} else {
@ -1923,16 +1924,17 @@ int ram_save_queue_pages(const char *rbname, ram_addr_t start, ram_addr_t len)
if (!ramblock) {
/* We shouldn't be asked for a non-existent RAMBlock */
error_report("ram_save_queue_pages no block '%s'", rbname);
error_setg(errp, "MIG_RP_MSG_REQ_PAGES has no block '%s'", rbname);
return -1;
}
rs->last_req_rb = ramblock;
}
trace_ram_save_queue_pages(ramblock->idstr, start, len);
if (!offset_in_ramblock(ramblock, start + len - 1)) {
error_report("%s request overrun start=" RAM_ADDR_FMT " len="
RAM_ADDR_FMT " blocklen=" RAM_ADDR_FMT,
__func__, start, len, ramblock->used_length);
error_setg(errp, "MIG_RP_MSG_REQ_PAGES request overrun, "
"start=" RAM_ADDR_FMT " len="
RAM_ADDR_FMT " blocklen=" RAM_ADDR_FMT,
start, len, ramblock->used_length);
return -1;
}
@ -1964,9 +1966,9 @@ int ram_save_queue_pages(const char *rbname, ram_addr_t start, ram_addr_t len)
assert(len % page_size == 0);
while (len) {
if (ram_save_host_page_urgent(pss)) {
error_report("%s: ram_save_host_page_urgent() failed: "
"ramblock=%s, start_addr=0x"RAM_ADDR_FMT,
__func__, ramblock->idstr, start);
error_setg(errp, "ram_save_host_page_urgent() failed: "
"ramblock=%s, start_addr=0x"RAM_ADDR_FMT,
ramblock->idstr, start);
ret = -1;
break;
}
@ -4110,7 +4112,7 @@ static int ram_dirty_bitmap_sync_all(MigrationState *s, RAMState *rs)
* This is only used when the postcopy migration is paused but wants
* to resume from a middle point.
*/
int ram_dirty_bitmap_reload(MigrationState *s, RAMBlock *block)
int ram_dirty_bitmap_reload(MigrationState *s, RAMBlock *block, Error **errp)
{
int ret = -EINVAL;
/* from_dst_file is always valid because we're within rp_thread */
@ -4124,8 +4126,8 @@ int ram_dirty_bitmap_reload(MigrationState *s, RAMBlock *block)
trace_ram_dirty_bitmap_reload_begin(block->idstr);
if (s->state != MIGRATION_STATUS_POSTCOPY_RECOVER) {
error_report("%s: incorrect state %s", __func__,
MigrationStatus_str(s->state));
error_setg(errp, "Reload bitmap in incorrect state %s",
MigrationStatus_str(s->state));
return -EINVAL;
}
@ -4142,9 +4144,8 @@ int ram_dirty_bitmap_reload(MigrationState *s, RAMBlock *block)
/* The size of the bitmap should match with our ramblock */
if (size != local_size) {
error_report("%s: ramblock '%s' bitmap size mismatch "
"(0x%"PRIx64" != 0x%"PRIx64")", __func__,
block->idstr, size, local_size);
error_setg(errp, "ramblock '%s' bitmap size mismatch (0x%"PRIx64
" != 0x%"PRIx64")", block->idstr, size, local_size);
return -EINVAL;
}
@ -4153,15 +4154,15 @@ int ram_dirty_bitmap_reload(MigrationState *s, RAMBlock *block)
ret = qemu_file_get_error(file);
if (ret || size != local_size) {
error_report("%s: read bitmap failed for ramblock '%s': %d"
" (size 0x%"PRIx64", got: 0x%"PRIx64")",
__func__, block->idstr, ret, local_size, size);
error_setg(errp, "read bitmap failed for ramblock '%s': %d"
" (size 0x%"PRIx64", got: 0x%"PRIx64")",
block->idstr, ret, local_size, size);
return -EIO;
}
if (end_mark != RAMBLOCK_RECV_BITMAP_ENDING) {
error_report("%s: ramblock '%s' end mark incorrect: 0x%"PRIx64,
__func__, block->idstr, end_mark);
error_setg(errp, "ramblock '%s' end mark incorrect: 0x%"PRIx64,
block->idstr, end_mark);
return -EINVAL;
}

5
migration/ram.h
View File

@ -50,7 +50,8 @@ uint64_t ram_bytes_total(void);
void mig_throttle_counter_reset(void);
uint64_t ram_pagesize_summary(void);
int ram_save_queue_pages(const char *rbname, ram_addr_t start, ram_addr_t len);
int ram_save_queue_pages(const char *rbname, ram_addr_t start, ram_addr_t len,
Error **errp);
void ram_postcopy_migrated_memory_release(MigrationState *ms);
/* For outgoing discard bitmap */
void ram_postcopy_send_discard_bitmap(MigrationState *ms);
@ -70,7 +71,7 @@ void ramblock_recv_bitmap_set(RAMBlock *rb, void *host_addr);
void ramblock_recv_bitmap_set_range(RAMBlock *rb, void *host_addr, size_t nr);
int64_t ramblock_recv_bitmap_send(QEMUFile *file,
const char *block_name);
int ram_dirty_bitmap_reload(MigrationState *s, RAMBlock *rb);
int ram_dirty_bitmap_reload(MigrationState *s, RAMBlock *rb, Error **errp);
bool ramblock_page_is_discarded(RAMBlock *rb, ram_addr_t start);
void postcopy_preempt_shutdown_file(MigrationState *s);
void *postcopy_preempt_thread(void *opaque);

4
migration/trace-events
View File

@ -150,8 +150,6 @@ multifd_tls_outgoing_handshake_complete(void *ioc) "ioc=%p"
multifd_set_outgoing_channel(void *ioc, const char *ioctype, const char *hostname) "ioc=%p ioctype=%s hostname=%s"
# migration.c
await_return_path_close_on_source_close(void) ""
await_return_path_close_on_source_joining(void) ""
migrate_set_state(const char *new_state) "new state %s"
migrate_fd_cleanup(void) ""
migrate_fd_error(const char *error_desc) "error=%s"
@ -168,7 +166,7 @@ migration_completion_postcopy_end_after_complete(void) ""
migration_rate_limit_pre(int ms) "%d ms"
migration_rate_limit_post(int urgent) "urgent: %d"
migration_return_path_end_before(void) ""
migration_return_path_end_after(int rp_error) "%d"
migration_return_path_end_after(void) ""
migration_thread_after_loop(void) ""
migration_thread_file_err(void) ""
migration_thread_setup_complete(void) ""