This diff converts the SRP list to a SMR list in rtsock.c
SRP is a bit strange with how it works and the SMR code is a bit easier to
understand. Since we can sleep in the SMR_TAILQ_FOREACH() we need to grab
a refcount on the route pcb so that we can leave the SMR critical section
and then enter the SMR critical section at the end of the loop before
dropping the refcount again.
The diff does not immeditaly explode but I doubt we can exploit
parallelism in route_input() so this may fail at some later stage if it is
wrong.
Comments from the lock critics welcome
--
:wq Claudio
Index: sys/net/rtsock.c
===================================================================
RCS file: /cvs/src/sys/net/rtsock.c,v
retrieving revision 1.334
diff -u -p -r1.334 rtsock.c
--- sys/net/rtsock.c 28 Jun 2022 10:01:13 -0000 1.334
+++ sys/net/rtsock.c 30 Jun 2022 08:02:09 -0000
@@ -71,7 +71,7 @@
#include <sys/domain.h>
#include <sys/pool.h>
#include <sys/protosw.h>
-#include <sys/srp.h>
+#include <sys/smr.h>
#include <net/if.h>
#include <net/if_dl.h>
@@ -107,8 +107,6 @@ struct walkarg {
};
void route_prinit(void);
-void rcb_ref(void *, void *);
-void rcb_unref(void *, void *);
int route_output(struct mbuf *, struct socket *, struct sockaddr *,
struct mbuf *);
int route_ctloutput(int, struct socket *, int, int, struct mbuf *);
@@ -149,7 +147,7 @@ int rt_setsource(unsigned int, struct
struct rtpcb {
struct socket *rop_socket; /* [I] */
- SRPL_ENTRY(rtpcb) rop_list;
+ SMR_TAILQ_ENTRY(rtpcb) rop_list;
struct refcnt rop_refcnt;
struct timeout rop_timeout;
unsigned int rop_msgfilter; /* [s] */
@@ -162,8 +160,7 @@ struct rtpcb {
#define sotortpcb(so) ((struct rtpcb *)(so)->so_pcb)
struct rtptable {
- SRPL_HEAD(, rtpcb) rtp_list;
- struct srpl_rc rtp_rc;
+ SMR_TAILQ_HEAD(, rtpcb) rtp_list;
struct rwlock rtp_lk;
unsigned int rtp_count;
};
@@ -185,29 +182,12 @@ struct rtptable rtptable;
void
route_prinit(void)
{
- srpl_rc_init(&rtptable.rtp_rc, rcb_ref, rcb_unref, NULL);
rw_init(&rtptable.rtp_lk, "rtsock");
- SRPL_INIT(&rtptable.rtp_list);
+ SMR_TAILQ_INIT(&rtptable.rtp_list);
pool_init(&rtpcb_pool, sizeof(struct rtpcb), 0,
IPL_SOFTNET, PR_WAITOK, "rtpcb", NULL);
}
-void
-rcb_ref(void *null, void *v)
-{
- struct rtpcb *rop = v;
-
- refcnt_take(&rop->rop_refcnt);
-}
-
-void
-rcb_unref(void *null, void *v)
-{
- struct rtpcb *rop = v;
-
- refcnt_rele_wake(&rop->rop_refcnt);
-}
-
int
route_usrreq(struct socket *so, int req, struct mbuf *m, struct mbuf *nam,
struct mbuf *control, struct proc *p)
@@ -325,8 +305,7 @@ route_attach(struct socket *so, int prot
so->so_options |= SO_USELOOPBACK;
rw_enter(&rtptable.rtp_lk, RW_WRITE);
- SRPL_INSERT_HEAD_LOCKED(&rtptable.rtp_rc, &rtptable.rtp_list, rop,
- rop_list);
+ SMR_TAILQ_INSERT_HEAD_LOCKED(&rtptable.rtp_list, rop, rop_list);
rtptable.rtp_count++;
rw_exit(&rtptable.rtp_lk);
@@ -347,8 +326,7 @@ route_detach(struct socket *so)
rw_enter(&rtptable.rtp_lk, RW_WRITE);
rtptable.rtp_count--;
- SRPL_REMOVE_LOCKED(&rtptable.rtp_rc, &rtptable.rtp_list, rop, rtpcb,
- rop_list);
+ SMR_TAILQ_REMOVE_LOCKED(&rtptable.rtp_list, rop, rop_list);
rw_exit(&rtptable.rtp_lk);
sounlock(so);
@@ -356,6 +334,7 @@ route_detach(struct socket *so)
/* wait for all references to drop */
refcnt_finalize(&rop->rop_refcnt, "rtsockrefs");
timeout_del_barrier(&rop->rop_timeout);
+ smr_barrier();
solock(so);
@@ -501,7 +480,6 @@ route_input(struct mbuf *m0, struct sock
struct rtpcb *rop;
struct rt_msghdr *rtm;
struct mbuf *m = m0;
- struct srp_ref sr;
/* ensure that we can access the rtm_type via mtod() */
if (m->m_len < offsetof(struct rt_msghdr, rtm_type) + 1) {
@@ -509,7 +487,8 @@ route_input(struct mbuf *m0, struct sock
return;
}
- SRPL_FOREACH(rop, &sr, &rtptable.rtp_list, rop_list) {
+ smr_read_enter();
+ SMR_TAILQ_FOREACH(rop, &rtptable.rtp_list, rop_list) {
/*
* If route socket is bound to an address family only send
* messages that match the address family. Address family
@@ -519,7 +498,8 @@ route_input(struct mbuf *m0, struct sock
rop->rop_proto != sa_family)
continue;
-
+ refcnt_take(&rop->rop_refcnt);
+ smr_read_leave();
so = rop->rop_socket;
solock(so);
@@ -579,8 +559,10 @@ route_input(struct mbuf *m0, struct sock
rtm_sendup(so, m);
next:
sounlock(so);
+ smr_read_enter();
+ refcnt_rele_wake(&rop->rop_refcnt);
}
- SRPL_LEAVE(&sr);
+ smr_read_leave();
m_freem(m);
}
