Re: [PATCH V1 01/32] savevm: add vmstate handler iterators

From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
To: Steve Sistare <steven.sistare@oracle.com>
Cc: "Daniel P. Berrange" <berrange@redhat.com>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	"Alex Bennée" <alex.bennee@linaro.org>,
	"Juan Quintela" <quintela@redhat.com>,
	qemu-devel@nongnu.org, "Markus Armbruster" <armbru@redhat.com>,
	"Alex Williamson" <alex.williamson@redhat.com>,
	"Stefan Hajnoczi" <stefanha@redhat.com>,
	"Marc-André Lureau" <marcandre.lureau@redhat.com>,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	"Philippe Mathieu-Daudé" <philmd@redhat.com>
Subject: Re: [PATCH V1 01/32] savevm: add vmstate handler iterators
Date: Fri, 11 Sep 2020 17:24:41 +0100	[thread overview]
Message-ID: <20200911162441.GJ3310@work-vm> (raw)
In-Reply-To: <1596122076-341293-2-git-send-email-steven.sistare@oracle.com>

Apologies for taking a while to get around to this, 

* Steve Sistare (steven.sistare@oracle.com) wrote:
> Provide the SAVEVM_FOREACH and SAVEVM_FORALL macros to loop over all save
> VM state handlers.  The former will filter handlers based on the operation
> in the later patch "savevm: VM handlers mode mask".  The latter loops over
> all handlers.
> 
> No functional change.
> 
> Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
> ---
>  migration/savevm.c | 57 ++++++++++++++++++++++++++++++++++++------------------
>  1 file changed, 38 insertions(+), 19 deletions(-)
> 
> diff --git a/migration/savevm.c b/migration/savevm.c
> index 45c9dd9..a07fcad 100644
> --- a/migration/savevm.c
> +++ b/migration/savevm.c
> @@ -266,6 +266,25 @@ static SaveState savevm_state = {
>      .global_section_id = 0,
>  };
>  
> +/*
> + * The FOREACH macros will filter handlers based on the current operation when
> + * additional conditions are added in a subsequent patch.
> + */
> +
> +#define SAVEVM_FOREACH(se, entry)                                    \
> +    QTAILQ_FOREACH(se, &savevm_state.handlers, entry)                \
> +
> +#define SAVEVM_FOREACH_SAFE(se, entry, new_se)                       \
> +    QTAILQ_FOREACH_SAFE(se, &savevm_state.handlers, entry, new_se)   \
> +
> +/* The FORALL macros unconditionally loop over all handlers. */
> +
> +#define SAVEVM_FORALL(se, entry)                                     \
> +    QTAILQ_FOREACH(se, &savevm_state.handlers, entry)
> +
> +#define SAVEVM_FORALL_SAFE(se, entry, new_se)                        \
> +    QTAILQ_FOREACH_SAFE(se, &savevm_state.handlers, entry, new_se)
> +

OK, can I ask you to merge this with the next patch but to spin it the
other way, so that we have:

  SAVEVM_FOR(se, entry, mask)

and the places you use SAVEVM_FORALL_SAFE would become

  SAVEVM_FOR(se, entry, VMS_MODE_ALL)

I'm thinking at some point in the future we could merge a bunch of the
other flag checks in there.

Dave

>  static bool should_validate_capability(int capability)
>  {
>      assert(capability >= 0 && capability < MIGRATION_CAPABILITY__MAX);
> @@ -673,7 +692,7 @@ static uint32_t calculate_new_instance_id(const char *idstr)
>      SaveStateEntry *se;
>      uint32_t instance_id = 0;
>  
> -    QTAILQ_FOREACH(se, &savevm_state.handlers, entry) {
> +    SAVEVM_FORALL(se, entry) {
>          if (strcmp(idstr, se->idstr) == 0
>              && instance_id <= se->instance_id) {
>              instance_id = se->instance_id + 1;
> @@ -689,7 +708,7 @@ static int calculate_compat_instance_id(const char *idstr)
>      SaveStateEntry *se;
>      int instance_id = 0;
>  
> -    QTAILQ_FOREACH(se, &savevm_state.handlers, entry) {
> +    SAVEVM_FORALL(se, entry) {
>          if (!se->compat) {
>              continue;
>          }
> @@ -803,7 +822,7 @@ void unregister_savevm(VMStateIf *obj, const char *idstr, void *opaque)
>      }
>      pstrcat(id, sizeof(id), idstr);
>  
> -    QTAILQ_FOREACH_SAFE(se, &savevm_state.handlers, entry, new_se) {
> +    SAVEVM_FORALL_SAFE(se, entry, new_se) {
>          if (strcmp(se->idstr, id) == 0 && se->opaque == opaque) {
>              savevm_state_handler_remove(se);
>              g_free(se->compat);
> @@ -867,7 +886,7 @@ void vmstate_unregister(VMStateIf *obj, const VMStateDescription *vmsd,
>  {
>      SaveStateEntry *se, *new_se;
>  
> -    QTAILQ_FOREACH_SAFE(se, &savevm_state.handlers, entry, new_se) {
> +    SAVEVM_FORALL_SAFE(se, entry, new_se) {
>          if (se->vmsd == vmsd && se->opaque == opaque) {
>              savevm_state_handler_remove(se);
>              g_free(se->compat);
> @@ -1119,7 +1138,7 @@ bool qemu_savevm_state_blocked(Error **errp)
>  {
>      SaveStateEntry *se;
>  
> -    QTAILQ_FOREACH(se, &savevm_state.handlers, entry) {
> +    SAVEVM_FORALL(se, entry) {
>          if (se->vmsd && se->vmsd->unmigratable) {
>              error_setg(errp, "State blocked by non-migratable device '%s'",
>                         se->idstr);
> @@ -1145,7 +1164,7 @@ bool qemu_savevm_state_guest_unplug_pending(void)
>  {
>      SaveStateEntry *se;
>  
> -    QTAILQ_FOREACH(se, &savevm_state.handlers, entry) {
> +    SAVEVM_FOREACH(se, entry) {
>          if (se->vmsd && se->vmsd->dev_unplug_pending &&
>              se->vmsd->dev_unplug_pending(se->opaque)) {
>              return true;
> @@ -1162,7 +1181,7 @@ void qemu_savevm_state_setup(QEMUFile *f)
>      int ret;
>  
>      trace_savevm_state_setup();
> -    QTAILQ_FOREACH(se, &savevm_state.handlers, entry) {
> +    SAVEVM_FOREACH(se, entry) {
>          if (!se->ops || !se->ops->save_setup) {
>              continue;
>          }
> @@ -1193,7 +1212,7 @@ int qemu_savevm_state_resume_prepare(MigrationState *s)
>  
>      trace_savevm_state_resume_prepare();
>  
> -    QTAILQ_FOREACH(se, &savevm_state.handlers, entry) {
> +    SAVEVM_FOREACH(se, entry) {
>          if (!se->ops || !se->ops->resume_prepare) {
>              continue;
>          }
> @@ -1223,7 +1242,7 @@ int qemu_savevm_state_iterate(QEMUFile *f, bool postcopy)
>      int ret = 1;
>  
>      trace_savevm_state_iterate();
> -    QTAILQ_FOREACH(se, &savevm_state.handlers, entry) {
> +    SAVEVM_FOREACH(se, entry) {
>          if (!se->ops || !se->ops->save_live_iterate) {
>              continue;
>          }
> @@ -1291,7 +1310,7 @@ void qemu_savevm_state_complete_postcopy(QEMUFile *f)
>      SaveStateEntry *se;
>      int ret;
>  
> -    QTAILQ_FOREACH(se, &savevm_state.handlers, entry) {
> +    SAVEVM_FOREACH(se, entry) {
>          if (!se->ops || !se->ops->save_live_complete_postcopy) {
>              continue;
>          }
> @@ -1324,7 +1343,7 @@ int qemu_savevm_state_complete_precopy_iterable(QEMUFile *f, bool in_postcopy)
>      SaveStateEntry *se;
>      int ret;
>  
> -    QTAILQ_FOREACH(se, &savevm_state.handlers, entry) {
> +    SAVEVM_FOREACH(se, entry) {
>          if (!se->ops ||
>              (in_postcopy && se->ops->has_postcopy &&
>               se->ops->has_postcopy(se->opaque)) ||
> @@ -1366,7 +1385,7 @@ int qemu_savevm_state_complete_precopy_non_iterable(QEMUFile *f,
>      vmdesc = qjson_new();
>      json_prop_int(vmdesc, "page_size", qemu_target_page_size());
>      json_start_array(vmdesc, "devices");
> -    QTAILQ_FOREACH(se, &savevm_state.handlers, entry) {
> +    SAVEVM_FOREACH(se, entry) {
>  
>          if ((!se->ops || !se->ops->save_state) && !se->vmsd) {
>              continue;
> @@ -1476,7 +1495,7 @@ void qemu_savevm_state_pending(QEMUFile *f, uint64_t threshold_size,
>      *res_postcopy_only = 0;
>  
>  
> -    QTAILQ_FOREACH(se, &savevm_state.handlers, entry) {
> +    SAVEVM_FOREACH(se, entry) {
>          if (!se->ops || !se->ops->save_live_pending) {
>              continue;
>          }
> @@ -1501,7 +1520,7 @@ void qemu_savevm_state_cleanup(void)
>      }
>  
>      trace_savevm_state_cleanup();
> -    QTAILQ_FOREACH(se, &savevm_state.handlers, entry) {
> +    SAVEVM_FOREACH(se, entry) {
>          if (se->ops && se->ops->save_cleanup) {
>              se->ops->save_cleanup(se->opaque);
>          }
> @@ -1580,7 +1599,7 @@ int qemu_save_device_state(QEMUFile *f)
>      }
>      cpu_synchronize_all_states();
>  
> -    QTAILQ_FOREACH(se, &savevm_state.handlers, entry) {
> +    SAVEVM_FOREACH(se, entry) {
>          int ret;
>  
>          if (se->is_ram) {
> @@ -1612,7 +1631,7 @@ static SaveStateEntry *find_se(const char *idstr, uint32_t instance_id)
>  {
>      SaveStateEntry *se;
>  
> -    QTAILQ_FOREACH(se, &savevm_state.handlers, entry) {
> +    SAVEVM_FORALL(se, entry) {
>          if (!strcmp(se->idstr, idstr) &&
>              (instance_id == se->instance_id ||
>               instance_id == se->alias_id))
> @@ -2334,7 +2353,7 @@ qemu_loadvm_section_part_end(QEMUFile *f, MigrationIncomingState *mis)
>      }
>  
>      trace_qemu_loadvm_state_section_partend(section_id);
> -    QTAILQ_FOREACH(se, &savevm_state.handlers, entry) {
> +    SAVEVM_FOREACH(se, entry) {
>          if (se->load_section_id == section_id) {
>              break;
>          }
> @@ -2400,7 +2419,7 @@ static int qemu_loadvm_state_setup(QEMUFile *f)
>      int ret;
>  
>      trace_loadvm_state_setup();
> -    QTAILQ_FOREACH(se, &savevm_state.handlers, entry) {
> +    SAVEVM_FOREACH(se, entry) {
>          if (!se->ops || !se->ops->load_setup) {
>              continue;
>          }
> @@ -2425,7 +2444,7 @@ void qemu_loadvm_state_cleanup(void)
>      SaveStateEntry *se;
>  
>      trace_loadvm_state_cleanup();
> -    QTAILQ_FOREACH(se, &savevm_state.handlers, entry) {
> +    SAVEVM_FOREACH(se, entry) {
>          if (se->ops && se->ops->load_cleanup) {
>              se->ops->load_cleanup(se->opaque);
>          }
> -- 
> 1.8.3.1
> 
-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK