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Re: [Qemu-devel] [PATCH 6/6] migration: Pass Error ** argument to {save,
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] [PATCH 6/6] migration: Pass Error ** argument to {save, load}_vmstate |
Date: |
Fri, 28 Apr 2017 17:13:48 +0100 |
User-agent: |
Mutt/1.8.0 (2017-02-23) |
* Markus Armbruster (address@hidden) wrote:
> "Dr. David Alan Gilbert" <address@hidden> writes:
>
> > * Juan Quintela (address@hidden) wrote:
> >> This way we use the "normal" way of printing errors for hmp commands.
> >>
> >> --
> >> Paolo suggestion
> >>
> >> Signed-off-by: Juan Quintela <address@hidden>
> >
> > <snip>
> >
> >> +int save_vmstate(const char *name, Error **errp)
> >> {
> >> BlockDriverState *bs, *bs1;
> >> QEMUSnapshotInfo sn1, *sn = &sn1, old_sn1, *old_sn = &old_sn1;
> >> @@ -2076,29 +2076,27 @@ int save_vmstate(const char *name)
> >> uint64_t vm_state_size;
> >> qemu_timeval tv;
> >> struct tm tm;
> >> - Error *local_err = NULL;
> >> AioContext *aio_context;
> >>
> >> if (!bdrv_all_can_snapshot(&bs)) {
> >> - error_report("Device '%s' is writable but does not support
> >> snapshots",
> >> - bdrv_get_device_name(bs));
> >> + error_setg(errp, "Device '%s' is writable but does not support "
> >> + "snapshots", bdrv_get_device_name(bs));
> >> return ret;
> >> }
> >>
> >> /* Delete old snapshots of the same name */
> >> if (name) {
> >> - ret = bdrv_all_delete_snapshot(name, &bs1, &local_err);
> >> + ret = bdrv_all_delete_snapshot(name, &bs1, errp);
> >> if (ret < 0) {
> >> - error_reportf_err(local_err,
> >> - "Error while deleting snapshot on device
> >> '%s': ",
> >> - bdrv_get_device_name(bs1));
> >> + error_prepend(errp, "Error while deleting snapshot on device "
> >> + "'%s': ", bdrv_get_device_name(bs1));
> >
> > I thought the rule was that you had to use a local_err and use
> > error_propagate?
> > (I hate that rule)
>
> Quote qapi/error.h:
>
> * Receive an error and pass it on to the caller:
> * Error *err = NULL;
> * foo(arg, &err);
> * if (err) {
> * handle the error...
> * error_propagate(errp, err);
> * }
> * where Error **errp is a parameter, by convention the last one.
> *
> * Do *not* "optimize" this to
> * foo(arg, errp);
> * if (*errp) { // WRONG!
> * handle the error...
> * }
> * because errp may be NULL!
> *
> * But when all you do with the error is pass it on, please use
> * foo(arg, errp);
> * for readability.
>
> Neglects to mention you can error_prepend() and still avoid
> error_propagate(), but the comment is long enough as it is.
Ah ok, that does make life easier.
> >> return ret;
> >> }
> >> }
> >>
> >> bs = bdrv_all_find_vmstate_bs();
> >> if (bs == NULL) {
> >> - error_report("No block device can accept snapshots");
> >> + error_setg(errp, "No block device can accept snapshots");
> >> return ret;
> >> }
> >> aio_context = bdrv_get_aio_context(bs);
> >> @@ -2107,7 +2105,7 @@ int save_vmstate(const char *name)
> >>
> >> ret = global_state_store();
> >> if (ret) {
> >> - error_report("Error saving global state");
> >> + error_setg(errp, "Error saving global state");
> >> return ret;
> >> }
> >> vm_stop(RUN_STATE_SAVE_VM);
> >> @@ -2139,21 +2137,20 @@ int save_vmstate(const char *name)
> >> /* save the VM state */
> >> f = qemu_fopen_bdrv(bs, 1);
> >> if (!f) {
> >> - error_report("Could not open VM state file");
> >> + error_setg(errp, "Could not open VM state file");
> >> goto the_end;
> >> }
> >> - ret = qemu_savevm_state(f, &local_err);
> >> + ret = qemu_savevm_state(f, errp);
> >> vm_state_size = qemu_ftell(f);
> >> qemu_fclose(f);
> >> if (ret < 0) {
> >> - error_report_err(local_err);
> >> goto the_end;
> >> }
> >>
> >> ret = bdrv_all_create_snapshot(sn, bs, vm_state_size, &bs);
> >> if (ret < 0) {
> >> - error_report("Error while creating snapshot on '%s'",
> >> - bdrv_get_device_name(bs));
> >> + error_setg(errp, "Error while creating snapshot on '%s'",
> >> + bdrv_get_device_name(bs));
> >> goto the_end;
> >> }
> >>
> >> @@ -2226,7 +2223,7 @@ void qmp_xen_load_devices_state(const char
> >> *filename, Error **errp)
> >> migration_incoming_state_destroy();
> >> }
> >>
> >> -int load_vmstate(const char *name)
> >> +int load_vmstate(const char *name, Error **errp)
> >> {
> >> BlockDriverState *bs, *bs_vm_state;
> >> QEMUSnapshotInfo sn;
> >> @@ -2236,20 +2233,22 @@ int load_vmstate(const char *name)
> >> MigrationIncomingState *mis = migration_incoming_get_current();
> >>
> >> if (!bdrv_all_can_snapshot(&bs)) {
> >> - error_report("Device '%s' is writable but does not support
> >> snapshots",
> >> - bdrv_get_device_name(bs));
> >> + error_setg(errp,
> >> + "Device '%s' is writable but does not support
> >> snapshots",
> >> + bdrv_get_device_name(bs));
> >> return -ENOTSUP;
> >> }
> >> ret = bdrv_all_find_snapshot(name, &bs);
> >> if (ret < 0) {
> >> - error_report("Device '%s' does not have the requested snapshot
> >> '%s'",
> >> - bdrv_get_device_name(bs), name);
> >> + error_setg(errp,
> >> + "Device '%s' does not have the requested snapshot
> >> '%s'",
> >> + bdrv_get_device_name(bs), name);
> >> return ret;
> >> }
> >>
> >> bs_vm_state = bdrv_all_find_vmstate_bs();
> >> if (!bs_vm_state) {
> >> - error_report("No block device supports snapshots");
> >> + error_setg(errp, "No block device supports snapshots");
> >> return -ENOTSUP;
> >> }
> >> aio_context = bdrv_get_aio_context(bs_vm_state);
> >> @@ -2261,8 +2260,8 @@ int load_vmstate(const char *name)
> >> if (ret < 0) {
> >> return ret;
> >> } else if (sn.vm_state_size == 0) {
> >> - error_report("This is a disk-only snapshot. Revert to it offline "
> >> - "using qemu-img.");
> >> + error_setg(errp, "This is a disk-only snapshot. Revert to it "
> >> + " offline using qemu-img");
> >> return -EINVAL;
> >> }
> >>
> >> @@ -2271,7 +2270,7 @@ int load_vmstate(const char *name)
> >>
> >> ret = bdrv_all_goto_snapshot(name, &bs);
> >> if (ret < 0) {
> >> - error_report("Error %d while activating snapshot '%s' on '%s'",
> >> + error_setg(errp, "Error %d while activating snapshot '%s' on
> >> '%s'",
> >> ret, name, bdrv_get_device_name(bs));
> >> return ret;
> >> }
> >> @@ -2279,7 +2278,7 @@ int load_vmstate(const char *name)
> >> /* restore the VM state */
> >> f = qemu_fopen_bdrv(bs_vm_state, 0);
> >> if (!f) {
> >> - error_report("Could not open VM state file");
> >> + error_setg(errp, "Could not open VM state file");
> >> return -EINVAL;
> >> }
> >>
> >> @@ -2293,7 +2292,7 @@ int load_vmstate(const char *name)
> >>
> >> migration_incoming_state_destroy();
> >> if (ret < 0) {
> >> - error_report("Error %d while loading VM state", ret);
> >> + error_setg(errp, "Error %d while loading VM state", ret);
> >> return ret;
> >> }
> >>
> >> diff --git a/replay/replay-snapshot.c b/replay/replay-snapshot.c
> >> index 8cced46..fdc4353 100644
> >> --- a/replay/replay-snapshot.c
> >> +++ b/replay/replay-snapshot.c
> >> @@ -62,14 +62,16 @@ void replay_vmstate_register(void)
> >>
> >> void replay_vmstate_init(void)
> >> {
> >> + Error *err = NULL;
> >> +
> >> if (replay_snapshot) {
> >> if (replay_mode == REPLAY_MODE_RECORD) {
> >> - if (save_vmstate(replay_snapshot) != 0) {
> >> + if (save_vmstate(replay_snapshot, &err) != 0) {
> >> error_report("Could not create snapshot for icount
> >> record");
> >> exit(1);
> >> }
> >> } else if (replay_mode == REPLAY_MODE_PLAY) {
> >> - if (load_vmstate(replay_snapshot) != 0) {
> >> + if (load_vmstate(replay_snapshot, &err) != 0) {
> >> error_report("Could not load snapshot for icount replay");
> >> exit(1);
> >> }
> >
> > How do either of the contents of the 'err' get reported - they're not
> > printed at all are they?
> > (I don't like error_abort, I'd rather see the other message as well).
>
> I guess you mean &error_fatal.
>
> Consider error_report_err().
Yes, thanks.
Dave
> >
> > Dave
> >
> >> diff --git a/vl.c b/vl.c
> >> index 0b4ed52..8b3ec2e 100644
> >> --- a/vl.c
> >> +++ b/vl.c
> >> @@ -4681,7 +4681,9 @@ int main(int argc, char **argv, char **envp)
> >> if (replay_mode != REPLAY_MODE_NONE) {
> >> replay_vmstate_init();
> >> } else if (loadvm) {
> >> - if (load_vmstate(loadvm) < 0) {
> >> + Error *local_err = NULL;
> >> + if (load_vmstate(loadvm, &local_err) < 0) {
> >> + error_report_err(local_err);
> >> autostart = 0;
> >> }
> >> }
> >> --
> >> 2.9.3
> >>
> >>
> > --
> > Dr. David Alan Gilbert / address@hidden / Manchester, UK
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
Re: [Qemu-devel] [PATCH 0/6] Move snapshots commands to hmp, Dr. David Alan Gilbert, 2017/04/28