net: mctp: Use hashtable for binds

Ensure that a specific EID (remote or local) bind will match in
preference to a MCTP_ADDR_ANY bind.

This adds infrastructure for binding a socket to receive messages from a
specific remote peer address, a future commit will expose an API for
this.

Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
Link: https://patch.msgid.link/20250710-mctp-bind-v4-5-8ec2f6460c56@codeconstruct.com.au
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

1 files changed, 16 insertions, 4 deletions

diff --git a/include/net/netns/mctp.h b/include/net/netns/mctp.h
index 1db8f9aaddb4..89555f90b97b 100644
--- a/include/net/netns/mctp.h
+++ b/include/net/netns/mctp.h
@@ -6,19 +6,25 @@
 #ifndef __NETNS_MCTP_H__
 #define __NETNS_MCTP_H__
 
+#include <linux/hash.h>
+#include <linux/hashtable.h>
 #include <linux/mutex.h>
 #include <linux/types.h>
 
+#define MCTP_BINDS_BITS 7
+
 struct netns_mctp {
 	/* Only updated under RTNL, entries freed via RCU */
 	struct list_head routes;
 
-	/* Bound sockets: list of sockets bound by type.
-	 * This list is updated from non-atomic contexts (under bind_lock),
-	 * and read (under rcu) in packet rx
+	/* Bound sockets: hash table of sockets, keyed by
+	 * (type, src_eid, dest_eid).
+	 * Specific src_eid/dest_eid entries also have an entry for
+	 * MCTP_ADDR_ANY. This list is updated from non-atomic contexts
+	 * (under bind_lock), and read (under rcu) in packet rx.
 	 */
 	struct mutex bind_lock;
-	struct hlist_head binds;
+	DECLARE_HASHTABLE(binds, MCTP_BINDS_BITS);
 
 	/* tag allocations. This list is read and updated from atomic contexts,
 	 * but elements are free()ed after a RCU grace-period
@@ -34,4 +40,10 @@ struct netns_mctp {
 	struct list_head neighbours;
 };
 
+static inline u32 mctp_bind_hash(u8 type, u8 local_addr, u8 peer_addr)
+{
+	return hash_32(type | (u32)local_addr << 8 | (u32)peer_addr << 16,
+		       MCTP_BINDS_BITS);
+}
+
 #endif /* __NETNS_MCTP_H__ */