On Thu, Oct 05, 2023 at 08:11:33AM +0200, Philippe Mathieu-Daudé wrote:
> Hi Peter,
>
> On 5/10/23 00:02, Peter Xu wrote:
> > 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*.
> >
> > - Use migrate_set_error() to apply that captured error to the global
> > migration object when error occured in this thread.
> >
> > - With above, no need to have mark_source_rp_bad(), remove it, alongside
> > with rp_state.error itself.
> >
> > Signed-off-by: Peter Xu <pet...@redhat.com>
> > ---
> > migration/migration.h | 1 -
> > migration/ram.h | 5 +-
> > migration/migration.c | 123 ++++++++++++++++++-----------------------
> > migration/ram.c | 41 +++++++-------
> > migration/trace-events | 4 +-
> > 5 files changed, 79 insertions(+), 95 deletions(-)
>
>
> > -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 */
>
>
> > @@ -4193,16 +4194,16 @@ 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);
> > ret = -EIO;
> > goto out;
> > }
> > 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);
> > ret = -EINVAL;
> > goto out;
> > }
>
> This function returns -EIO/-EINVAL errors, propagated to its 2 callers
> - migrate_handle_rp_recv_bitmap()
> - migrate_handle_rp_resume_ack()
It was only called in migrate_handle_rp_recv_bitmap(), but I think I see
what you meant..
> which are only used in source_return_path_thread() where the return
> value is only checked as boolean.
>
> Could we simplify them returning a boolean (which is the pattern with
> functions taking an Error** as last parameter)?
Yes, with errp passed in, the "int" retcode is slightly duplicated. I can
add one more patch on top of this as further cleanup, as below.
Thanks,
===8<===
>From b1052befd72beb129012afddf5647339fe4e257c Mon Sep 17 00:00:00 2001
From: Peter Xu <pet...@redhat.com>
Date: Thu, 5 Oct 2023 12:03:44 -0400
Subject: [PATCH] migration: Change ram_dirty_bitmap_reload() retval to bool
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Now we have a Error** passed into the return path thread stack, which is
even clearer than an int retval. Change ram_dirty_bitmap_reload() and the
callers to use a bool instead to replace errnos.
Suggested-by: Philippe Mathieu-Daudé <phi...@linaro.org>
Signed-off-by: Peter Xu <pet...@redhat.com>
---
migration/ram.h | 2 +-
migration/migration.c | 18 +++++++++---------
migration/ram.c | 24 +++++++++++-------------
3 files changed, 21 insertions(+), 23 deletions(-)
diff --git a/migration/ram.h b/migration/ram.h
index 14ed666d58..af0290f8ab 100644
--- a/migration/ram.h
+++ b/migration/ram.h
@@ -72,7 +72,7 @@ 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, Error **errp);
+bool 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);
diff --git a/migration/migration.c b/migration/migration.c
index 1a7f214fcf..e7375810be 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -1837,29 +1837,29 @@ static void migrate_handle_rp_req_pages(MigrationState
*ms, const char* rbname,
ram_save_queue_pages(rbname, start, len, errp);
}
-static int migrate_handle_rp_recv_bitmap(MigrationState *s, char *block_name,
- Error **errp)
+static bool migrate_handle_rp_recv_bitmap(MigrationState *s, char *block_name,
+ Error **errp)
{
RAMBlock *block = qemu_ram_block_by_name(block_name);
if (!block) {
error_setg(errp, "MIG_RP_MSG_RECV_BITMAP has invalid block name '%s'",
block_name);
- return -EINVAL;
+ return false;
}
/* Fetch the received bitmap and refresh the dirty bitmap */
return ram_dirty_bitmap_reload(s, block, errp);
}
-static int migrate_handle_rp_resume_ack(MigrationState *s,
- uint32_t value, Error **errp)
+static bool 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_setg(errp, "illegal resume_ack value %"PRIu32, value);
- return -1;
+ return false;
}
/* Now both sides are active. */
@@ -1869,7 +1869,7 @@ static int migrate_handle_rp_resume_ack(MigrationState *s,
/* Notify send thread that time to continue send pages */
migration_rp_kick(s);
- return 0;
+ return true;
}
/*
@@ -2021,14 +2021,14 @@ static void *source_return_path_thread(void *opaque)
}
/* Format: len (1B) + idstr (<255B). This ends the idstr. */
buf[buf[0] + 1] = '\0';
- if (migrate_handle_rp_recv_bitmap(ms, (char *)(buf + 1), &err)) {
+ 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, &err)) {
+ if (!migrate_handle_rp_resume_ack(ms, tmp32, &err)) {
goto out;
}
break;
diff --git a/migration/ram.c b/migration/ram.c
index 2565f53f5c..982fbbeee1 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -4157,23 +4157,25 @@ static int ram_dirty_bitmap_sync_all(MigrationState *s,
RAMState *rs)
* Read the received bitmap, revert it as the initial dirty bitmap.
* This is only used when the postcopy migration is paused but wants
* to resume from a middle point.
+ *
+ * Returns true if succeeded, false for errors.
*/
-int ram_dirty_bitmap_reload(MigrationState *s, RAMBlock *block, Error **errp)
+bool 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 */
QEMUFile *file = s->rp_state.from_dst_file;
unsigned long *le_bitmap, nbits = block->used_length >> TARGET_PAGE_BITS;
uint64_t local_size = DIV_ROUND_UP(nbits, 8);
uint64_t size, end_mark;
RAMState *rs = ram_state;
+ bool result = false;
trace_ram_dirty_bitmap_reload_begin(block->idstr);
if (s->state != MIGRATION_STATUS_POSTCOPY_RECOVER) {
error_setg(errp, "Reload bitmap in incorrect state %s",
MigrationStatus_str(s->state));
- return -EINVAL;
+ return false;
}
/*
@@ -4191,26 +4193,22 @@ int ram_dirty_bitmap_reload(MigrationState *s, RAMBlock
*block, Error **errp)
if (size != local_size) {
error_setg(errp, "ramblock '%s' bitmap size mismatch (0x%"PRIx64
" != 0x%"PRIx64")", block->idstr, size, local_size);
- ret = -EINVAL;
goto out;
}
size = qemu_get_buffer(file, (uint8_t *)le_bitmap, local_size);
end_mark = qemu_get_be64(file);
- ret = qemu_file_get_error(file);
- if (ret || size != local_size) {
- error_setg(errp, "read bitmap failed for ramblock '%s': %d"
- " (size 0x%"PRIx64", got: 0x%"PRIx64")",
- block->idstr, ret, local_size, size);
- ret = -EIO;
+ if (qemu_file_get_error(file) || size != local_size) {
+ error_setg(errp, "read bitmap failed for ramblock '%s': "
+ "(size 0x%"PRIx64", got: 0x%"PRIx64")",
+ block->idstr, local_size, size);
goto out;
}
if (end_mark != RAMBLOCK_RECV_BITMAP_ENDING) {
error_setg(errp, "ramblock '%s' end mark incorrect: 0x%"PRIx64,
block->idstr, end_mark);
- ret = -EINVAL;
goto out;
}
@@ -4243,10 +4241,10 @@ int ram_dirty_bitmap_reload(MigrationState *s, RAMBlock
*block, Error **errp)
*/
migration_rp_kick(s);
- ret = 0;
+ result = true;
out:
g_free(le_bitmap);
- return ret;
+ return result;
}
static int ram_resume_prepare(MigrationState *s, void *opaque)
--
2.41.0
--
Peter Xu
