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envelope-from=farosas@suse.de; helo=smtp-out1.suse.de X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, SPF_HELO_NONE=0.001, T_SPF_TEMPERROR=0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Peter Xu writes: > On Mon, Jun 30, 2025 at 04:59:03PM -0300, Fabiano Rosas wrote: >> Convert the code in migrate_params_test_apply() from an open-coded >> copy of every migration parameter to a copy using visitors. The >> current code has conditionals for each parameter's has_* field, which >> is exactly what the visitors do. >> >> This hides the details of QAPI from the migration code and avoids the >> need to update migrate_params_test_apply() every time a new migration >> parameter is added. Both were very confusing and while the visitor >> code can become a bit involved, there is no need for new contributors >> to ever touch it. >> >> Change the name of the function to a more direct reference of what it >> does: merging the user params with the temporary copy. >> >> Move the QAPI_CLONE_MEMBERS into the caller, so QAPI_CLONE can be used >> and there's no need to allocate memory in the migration >> code. Similarly, turn 'tmp' into a pointer so the proper qapi_free_ >> routine can be used. >> >> An extra call to migrate_mark_all_params_present() is now needed >> because the visitors update the has_ field for non-present fields, but >> we actually want them all set so migrate_params_apply() can copy all >> of them. >> >> Signed-off-by: Fabiano Rosas >> --- >> migration/options.c | 157 +++++++++++++++----------------------------- >> 1 file changed, 54 insertions(+), 103 deletions(-) >> >> diff --git a/migration/options.c b/migration/options.c >> index 6619b5f21a..695bec5b8f 100644 >> --- a/migration/options.c >> +++ b/migration/options.c >> @@ -20,6 +20,10 @@ >> #include "qapi/qapi-commands-migration.h" >> #include "qapi/qapi-visit-migration.h" >> #include "qapi/qmp/qerror.h" >> +#include "qapi/qobject-input-visitor.h" >> +#include "qapi/qobject-output-visitor.h" >> +#include "qapi/visitor.h" >> +#include "qobject/qdict.h" >> #include "qobject/qnull.h" >> #include "system/runstate.h" >> #include "migration/colo.h" >> @@ -1223,120 +1227,63 @@ bool migrate_params_check(MigrationParameters *params, Error **errp) >> return true; >> } >> >> -static void migrate_params_test_apply(MigrationParameters *params, >> - MigrationParameters *dest) >> +static bool migrate_params_merge(MigrationParameters *dst, >> + MigrationParameters *src, Error **errp) >> { >> - MigrationState *s = migrate_get_current(); >> + QObject *ret_out = NULL; >> + Visitor *v; >> + bool ok; >> >> - QAPI_CLONE_MEMBERS(MigrationParameters, dest, &s->parameters); >> - >> - if (params->has_throttle_trigger_threshold) { >> - dest->throttle_trigger_threshold = params->throttle_trigger_threshold; >> - } >> - >> - if (params->has_cpu_throttle_initial) { >> - dest->cpu_throttle_initial = params->cpu_throttle_initial; >> - } >> - >> - if (params->has_cpu_throttle_increment) { >> - dest->cpu_throttle_increment = params->cpu_throttle_increment; >> + /* free memory from pointers that are about to be assigned */ >> + if (src->has_block_bitmap_mapping) { >> + qapi_free_BitmapMigrationNodeAliasList(dst->block_bitmap_mapping); > > There're quite a few similar cases like this one in this series (including > the rest below parameters below), where we free stuff but keep the dangling > pointer around for a while (..hopefully!).. > > Should we still try to reset the pointers? Am I the only one that is > nervous with it? > Yeah, no worries, I can clear them all just to be sure. >> } >> >> - if (params->has_cpu_throttle_tailslow) { >> - dest->cpu_throttle_tailslow = params->cpu_throttle_tailslow; >> + if (src->tls_creds) { >> + qapi_free_StrOrNull(dst->tls_creds); >> } >> >> - if (params->tls_creds) { >> - qapi_free_StrOrNull(dest->tls_creds); >> - dest->tls_creds = QAPI_CLONE(StrOrNull, params->tls_creds); >> + if (src->tls_hostname) { >> + qapi_free_StrOrNull(dst->tls_hostname); >> } >> >> - if (params->tls_hostname) { >> - qapi_free_StrOrNull(dest->tls_hostname); >> - dest->tls_hostname = QAPI_CLONE(StrOrNull, params->tls_hostname); >> + if (src->tls_authz) { >> + qapi_free_StrOrNull(dst->tls_authz); >> } >> >> - if (params->tls_authz) { >> - qapi_free_StrOrNull(dest->tls_authz); >> - dest->tls_authz = QAPI_CLONE(StrOrNull, params->tls_authz); >> + /* read in from src */ >> + v = qobject_output_visitor_new(&ret_out); >> + ok = visit_type_MigrationParameters(v, NULL, &src, errp); >> + if (!ok) { >> + goto out; >> } >> + visit_complete(v, &ret_out); >> + visit_free(v); >> >> - if (params->has_max_bandwidth) { >> - dest->max_bandwidth = params->max_bandwidth; >> + /* >> + * Write to dst but leave existing fields intact (except for has_* >> + * which will be updated according to their presence in src). >> + */ >> + v = qobject_input_visitor_new(ret_out); >> + ok = visit_start_struct(v, NULL, NULL, 0, errp); >> + if (!ok) { >> + goto out; >> } >> - >> - if (params->has_avail_switchover_bandwidth) { >> - dest->avail_switchover_bandwidth = params->avail_switchover_bandwidth; >> + ok = visit_type_MigrationParameters_members(v, dst, errp); >> + if (!ok) { >> + goto out; >> } >> - >> - if (params->has_downtime_limit) { >> - dest->downtime_limit = params->downtime_limit; >> + ok = visit_check_struct(v, errp); >> + visit_end_struct(v, NULL); >> + if (!ok) { >> + goto out; >> } >> >> - if (params->has_x_checkpoint_delay) { >> - dest->x_checkpoint_delay = params->x_checkpoint_delay; >> - } >> +out: >> + visit_free(v); >> + qobject_unref(ret_out); > > IIUC this is essential the trick we used to play before QAPI_CLONE, before > commit a15fcc3cf69e. > > https://lore.kernel.org/all/1465490926-28625-15-git-send-email-eblake@redhat.com/ > > Yes, looks similar.. > > QAPI_CLONE_MEMBERS() will copy everything, which we do not want here. We > only want to copy where has_* is set. So it's indeed a sligntly different > request versus the current clone API. > > IIUC that can be implemented using a similar qapi clone visitor, however > instead of g_memdup() on the structs/lists first (or in the case of > QAPI_CLONE_MEMBERS, we did *dst=*src), we lazy copy all the fields. > > I wished this is a generic API we could use. I think it means we'll > maintain this ourselves. Maybe it's OK. > I'm not sure how easy it is to provide a generic API for this. I don't think there's much space for this code to change anyway, so is fine to keep it in migration. I'll try to implement a QAPI_CLONE_PRESENT_MEMBERS, let's see. >> >> - if (params->has_multifd_channels) { >> - dest->multifd_channels = params->multifd_channels; >> - } >> - if (params->has_multifd_compression) { >> - dest->multifd_compression = params->multifd_compression; >> - } >> - if (params->has_multifd_qatzip_level) { >> - dest->multifd_qatzip_level = params->multifd_qatzip_level; >> - } >> - if (params->has_multifd_zlib_level) { >> - dest->multifd_zlib_level = params->multifd_zlib_level; >> - } >> - if (params->has_multifd_zstd_level) { >> - dest->multifd_zstd_level = params->multifd_zstd_level; >> - } >> - if (params->has_xbzrle_cache_size) { >> - dest->xbzrle_cache_size = params->xbzrle_cache_size; >> - } >> - if (params->has_max_postcopy_bandwidth) { >> - dest->max_postcopy_bandwidth = params->max_postcopy_bandwidth; >> - } >> - if (params->has_max_cpu_throttle) { >> - dest->max_cpu_throttle = params->max_cpu_throttle; >> - } >> - if (params->has_announce_initial) { >> - dest->announce_initial = params->announce_initial; >> - } >> - if (params->has_announce_max) { >> - dest->announce_max = params->announce_max; >> - } >> - if (params->has_announce_rounds) { >> - dest->announce_rounds = params->announce_rounds; >> - } >> - if (params->has_announce_step) { >> - dest->announce_step = params->announce_step; >> - } >> - >> - if (params->has_block_bitmap_mapping) { >> - dest->block_bitmap_mapping = params->block_bitmap_mapping; >> - } >> - >> - if (params->has_x_vcpu_dirty_limit_period) { >> - dest->x_vcpu_dirty_limit_period = >> - params->x_vcpu_dirty_limit_period; >> - } >> - if (params->has_vcpu_dirty_limit) { >> - dest->vcpu_dirty_limit = params->vcpu_dirty_limit; >> - } >> - >> - if (params->has_mode) { >> - dest->mode = params->mode; >> - } >> - >> - if (params->has_zero_page_detection) { >> - dest->zero_page_detection = params->zero_page_detection; >> - } >> - >> - if (params->has_direct_io) { >> - dest->direct_io = params->direct_io; >> - } >> + return ok; >> } >> >> static void migrate_params_apply(MigrationParameters *params) >> @@ -1353,7 +1300,9 @@ static void migrate_params_apply(MigrationParameters *params) >> >> void qmp_migrate_set_parameters(MigrationParameters *params, Error **errp) >> { >> - MigrationParameters tmp; >> + MigrationState *s = migrate_get_current(); >> + g_autoptr(MigrationParameters) tmp = QAPI_CLONE(MigrationParameters, >> + &s->parameters); >> >> /* >> * Convert QTYPE_QNULL and NULL to the empty string (""). Even >> @@ -1367,7 +1316,9 @@ void qmp_migrate_set_parameters(MigrationParameters *params, Error **errp) >> tls_opt_to_str(¶ms->tls_hostname); >> tls_opt_to_str(¶ms->tls_authz); >> >> - migrate_params_test_apply(params, &tmp); >> + if (!migrate_params_merge(tmp, params, errp)) { >> + return; >> + } >> >> /* >> * Mark block_bitmap_mapping as present now while we have the >> @@ -1377,10 +1328,10 @@ void qmp_migrate_set_parameters(MigrationParameters *params, Error **errp) >> migrate_get_current()->has_block_bitmap_mapping = true; >> } >> >> - if (migrate_params_check(&tmp, errp)) { >> - migrate_params_apply(&tmp); >> + if (migrate_params_check(tmp, errp)) { >> + /* mark all present, so they're all copied */ >> + migrate_mark_all_params_present(tmp); > > Ah, I just asked a question in the previous patch on what happens if some > of the fields will be present. Looks like this line is the answer? > Yes, it's either here, or via migrate_param_init(). > This isn't very obvious. Maybe some comment in migrate_params_apply() > would slightly help (which mentions it must be used when all parameters are > set)? Or some way to assert it? > Yep, I'll add more safeguards. >> + migrate_params_apply(tmp); >> migrate_post_update_params(params, errp); >> } >> - >> - migrate_tls_opts_free(&tmp); >> } >> -- >> 2.35.3 >>