Add an optional callback function that will be invoked when a per-CPU

queue was drained.  It will never fire for a directly dispatched packet.

You will most likely never want to use this for any ordinary netisr usage
and you will never blame netisr in case you try to use it and it does
not work as expected.

Reviewed by:	rwatson

3 files changed, 14 insertions, 1 deletions

diff --git a/share/man/man9/netisr.9 b/share/man/man9/netisr.9
index d54b6ff..b4062e0 100644
--- a/share/man/man9/netisr.9
+++ b/share/man/man9/netisr.9
@@ -27,7 +27,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd June 7, 2009
+.Dd June 14, 2009
 .Dt NETISR 9
 .Os
 .Sh NAME
@@ -137,6 +137,13 @@ Will be used only with
 Protocol function to determine what CPU a packet should be processed on.
 Will be used only with
 .Dv NETISR_POLICY_CPU .
+.It Vt netisr_drainedcpu_t Va nh_drainedcpu
+Optional callback function that will be invoked when a per-CPU queue
+was drained.
+It will never fire for directly dispatched packets.
+Unless fully understood, this special-purpose function should not be used.
+.\" In case you intend to use this please send 50 chocolate bars to each
+.\" of rwatson and bz and wait for an answer.
 .It Vt u_int Va nh_proto
 Protocol number used by both protocols to identify themselves to
 .Nm ,
diff --git a/sys/net/netisr.c b/sys/net/netisr.c
index da5dac4..5dc4c90 100644
--- a/sys/net/netisr.c
+++ b/sys/net/netisr.c
@@ -197,6 +197,7 @@ struct netisr_proto {
 	netisr_handler_t *np_handler;	/* Protocol handler. */
 	netisr_m2flow_t	*np_m2flow;	/* Query flow for untagged packet. */
 	netisr_m2cpuid_t *np_m2cpuid;	/* Query CPU to process packet on. */
+	netisr_drainedcpu_t *np_drainedcpu; /* Callback when drained a queue. */
 	u_int		 np_qlimit;	/* Maximum per-CPU queue depth. */
 	u_int		 np_policy;	/* Work placement policy. */
 };
@@ -380,6 +381,7 @@ netisr_register(const struct netisr_handler *nhp)
 	np[proto].np_handler = nhp->nh_handler;
 	np[proto].np_m2flow = nhp->nh_m2flow;
 	np[proto].np_m2cpuid = nhp->nh_m2cpuid;
+	np[proto].np_drainedcpu = nhp->nh_drainedcpu;
 	if (nhp->nh_qlimit == 0)
 		np[proto].np_qlimit = netisr_defaultqlimit;
 	else if (nhp->nh_qlimit > netisr_maxqlimit) {
@@ -705,6 +707,8 @@ netisr_process_workstream_proto(struct netisr_workstream *nwsp, u_int proto)
 	}
 	KASSERT(local_npw.nw_len == 0,
 	    ("%s(%u): len %u", __func__, proto, local_npw.nw_len));
+	if (np[proto].np_drainedcpu)
+		np[proto].np_drainedcpu(nwsp->nws_cpu);
 	NWS_LOCK(nwsp);
 	npwp->nw_handled += handled;
 	return (handled);
diff --git a/sys/net/netisr.h b/sys/net/netisr.h
index 5894d3d..ec7df3a 100644
--- a/sys/net/netisr.h
+++ b/sys/net/netisr.h
@@ -88,6 +88,7 @@ typedef void		 netisr_handler_t (struct mbuf *m);
 typedef struct mbuf	*netisr_m2cpuid_t(struct mbuf *m, uintptr_t source,
 			 u_int *cpuid);
 typedef	struct mbuf	*netisr_m2flow_t(struct mbuf *m, uintptr_t source);
+typedef void		 netisr_drainedcpu_t(u_int cpuid);
 
 #define	NETISR_POLICY_SOURCE	1	/* Maintain source ordering. */
 #define	NETISR_POLICY_FLOW	2	/* Maintain flow ordering. */
@@ -101,6 +102,7 @@ struct netisr_handler {
 	netisr_handler_t *nh_handler;	/* Protocol handler. */
 	netisr_m2flow_t	*nh_m2flow;	/* Query flow for untagged packet. */
 	netisr_m2cpuid_t *nh_m2cpuid;	/* Query CPU to process mbuf on. */
+	netisr_drainedcpu_t *nh_drainedcpu; /* Callback when drained a queue. */
 	u_int		 nh_proto;	/* Integer protocol ID. */
 	u_int		 nh_qlimit;	/* Maximum per-CPU queue depth. */
 	u_int		 nh_policy;	/* Work placement policy. */