On Tue, Mar 10, 2015 at 02:34:03PM +0000, Dr. David Alan Gilbert wrote: > * David Gibson (david@gibson.dropbear.id.au) wrote: > > On Wed, Feb 25, 2015 at 04:51:34PM +0000, Dr. David Alan Gilbert (git) wrote: > > > From: "Dr. David Alan Gilbert" > > > > > > Add migrate_send_rp_message to send a message from destination to source along the return path. > > > (It uses a mutex to let it be called from multiple threads) > > > Add migrate_send_rp_shut to send a 'shut' message to indicate > > > the destination is finished with the RP. > > > Add migrate_send_rp_ack to send a 'PONG' message in response to a PING > > > Use it in the CMD_PING handler > > > > > > Signed-off-by: Dr. David Alan Gilbert > > > --- > > > include/migration/migration.h | 17 ++++++++++++++++ > > > migration/migration.c | 45 +++++++++++++++++++++++++++++++++++++++++++ > > > savevm.c | 2 +- > > > trace-events | 1 + > > > 4 files changed, 64 insertions(+), 1 deletion(-) > > > > > > diff --git a/include/migration/migration.h b/include/migration/migration.h > > > index c514dd4..6775747 100644 > > > --- a/include/migration/migration.h > > > +++ b/include/migration/migration.h > > > @@ -41,6 +41,13 @@ struct MigrationParams { > > > bool shared; > > > }; > > > > > > +/* Commands sent on the return path from destination to source*/ > > > +enum mig_rpcomm_cmd { > > > > "command" doesn't seem like quite the right description for these rp > > messages. > > Would you prefer 'message' ? Perhaps "message type" to distinguish from the the blob including both tag and data. > > > + MIG_RP_CMD_INVALID = 0, /* Must be 0 */ > > > + MIG_RP_CMD_SHUT, /* sibling will not send any more RP messages */ > > > + MIG_RP_CMD_PONG, /* Response to a PING; data (seq: be32 ) */ > > > +}; > > > + > > > typedef struct MigrationState MigrationState; > > > > > > /* State for the incoming migration */ > > > @@ -48,6 +55,7 @@ struct MigrationIncomingState { > > > QEMUFile *file; > > > > > > QEMUFile *return_path; > > > + QemuMutex rp_mutex; /* We send replies from multiple threads */ > > > }; > > > > > > MigrationIncomingState *migration_incoming_get_current(void); > > > @@ -169,6 +177,15 @@ int64_t migrate_xbzrle_cache_size(void); > > > > > > int64_t xbzrle_cache_resize(int64_t new_size); > > > > > > +/* Sending on the return path - generic and then for each message type */ > > > +void migrate_send_rp_message(MigrationIncomingState *mis, > > > + enum mig_rpcomm_cmd cmd, > > > + uint16_t len, uint8_t *data); > > > +void migrate_send_rp_shut(MigrationIncomingState *mis, > > > + uint32_t value); > > > +void migrate_send_rp_pong(MigrationIncomingState *mis, > > > + uint32_t value); > > > + > > > void ram_control_before_iterate(QEMUFile *f, uint64_t flags); > > > void ram_control_after_iterate(QEMUFile *f, uint64_t flags); > > > void ram_control_load_hook(QEMUFile *f, uint64_t flags); > > > diff --git a/migration/migration.c b/migration/migration.c > > > index a36ea65..80d234c 100644 > > > --- a/migration/migration.c > > > +++ b/migration/migration.c > > > @@ -78,6 +78,7 @@ MigrationIncomingState *migration_incoming_state_new(QEMUFile* f) > > > { > > > mis_current = g_malloc0(sizeof(MigrationIncomingState)); > > > mis_current->file = f; > > > + qemu_mutex_init(&mis_current->rp_mutex); > > > > > > return mis_current; > > > } > > > @@ -88,6 +89,50 @@ void migration_incoming_state_destroy(void) > > > mis_current = NULL; > > > } > > > > > > +/* > > > + * Send a message on the return channel back to the source > > > + * of the migration. > > > + */ > > > +void migrate_send_rp_message(MigrationIncomingState *mis, > > > + enum mig_rpcomm_cmd cmd, > > > + uint16_t len, uint8_t *data) > > > > Using (void *) for data would avoid casts in a bunch of the callers. > > Fixed; thanks. > > > > +{ > > > + trace_migrate_send_rp_message((int)cmd, len); > > > + qemu_mutex_lock(&mis->rp_mutex); > > > + qemu_put_be16(mis->return_path, (unsigned int)cmd); > > > + qemu_put_be16(mis->return_path, len); > > > + qemu_put_buffer(mis->return_path, data, len); > > > + qemu_fflush(mis->return_path); > > > + qemu_mutex_unlock(&mis->rp_mutex); > > > +} > > > + > > > +/* > > > + * Send a 'SHUT' message on the return channel with the given value > > > + * to indicate that we've finished with the RP. None-0 value indicates > > > + * error. > > > + */ > > > +void migrate_send_rp_shut(MigrationIncomingState *mis, > > > + uint32_t value) > > > +{ > > > + uint32_t buf; > > > + > > > + buf = cpu_to_be32(value); > > > + migrate_send_rp_message(mis, MIG_RP_CMD_SHUT, 4, (uint8_t *)&buf); > > > > ^ sizeof(buf) > > would be safer > > Done. > > > > +} > > > + > > > +/* > > > + * Send a 'PONG' message on the return channel with the given value > > > + * (normally in response to a 'PING') > > > + */ > > > +void migrate_send_rp_pong(MigrationIncomingState *mis, > > > + uint32_t value) > > > +{ > > > + uint32_t buf; > > > + > > > + buf = cpu_to_be32(value); > > > + migrate_send_rp_message(mis, MIG_RP_CMD_PONG, 4, (uint8_t *)&buf); > > > > It occurs to me that you could define PONG as returning the whole > > buffer that PING sends, instead of just 4-bytes. Might allow for some > > more testing of variable sized messages. > > Yes; although it would complicate things a lot if I made it fully generic > because I'd have to worry about allocating a buffer etc and I'm not > making vast use of the 4 bytes I've already got. Couldn't migrate_send_rp_pong just take a buf pointer and length, then you can point that directly at the buffer in the ping message you've received. -- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson