For each kdbus domain, we maintain an ID-counter to guarantee unique IDs across all objects. We also used to use it for message IDs. However, this requires touching a shared cacheline on each message transaction, even though we never guaranteed global ordering across buses, anyway.
Introduce a separate counter which is used solely for message IDs. Semantics stay the same, but it no longer relates to IDs across buses. Reviewed-by: Daniel Mack <dan...@zonque.org> Signed-off-by: David Herrmann <dh.herrm...@gmail.com> --- ipc/kdbus/bus.h | 2 ++ ipc/kdbus/message.c | 2 +- 2 files changed, 3 insertions(+), 1 deletion(-) diff --git a/ipc/kdbus/bus.h b/ipc/kdbus/bus.h index 238986e..8c2acae 100644 --- a/ipc/kdbus/bus.h +++ b/ipc/kdbus/bus.h @@ -44,6 +44,7 @@ struct kdbus_user; * @domain: Domain of this bus * @creator: Creator of the bus * @creator_meta: Meta information about the bus creator + * @last_message_id: Last used message id * @policy_db: Policy database for this bus * @name_registry: Name registry of this bus * @conn_rwlock: Read/Write lock for all lists of child connections @@ -67,6 +68,7 @@ struct kdbus_bus { struct kdbus_meta_proc *creator_meta; /* protected by own locks */ + atomic64_t last_message_id; struct kdbus_policy_db policy_db; struct kdbus_name_registry *name_registry; diff --git a/ipc/kdbus/message.c b/ipc/kdbus/message.c index 432dba4..ae565cd 100644 --- a/ipc/kdbus/message.c +++ b/ipc/kdbus/message.c @@ -671,7 +671,7 @@ static struct kdbus_staging *kdbus_staging_new(struct kdbus_bus *bus, if (!staging) return ERR_PTR(-ENOMEM); - staging->msg_seqnum = atomic64_inc_return(&bus->domain->last_id); + staging->msg_seqnum = atomic64_inc_return(&bus->last_message_id); staging->n_parts = 0; /* we reserve n_parts, but don't enforce them */ staging->parts = (void *)(staging + 1); -- 2.5.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/