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Code Issues Releases Activity

pfil(9) locking take 3: Switch to rmlock(9)

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This has the benefit that rmlocks have proper support for reader recursion
(in contrast to rwlock(9) which could potential lead to writer stravation).
It also means a significant performance gain, eventhough only visible in
microbenchmarks at the moment.

Discussed on:	-arch, -net
This commit is contained in:
Max Laier 2007-11-25 12:41:47 +00:00
parent 9c5ce94257
commit 1030a1a9cb
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=173904
2 changed files with 15 additions and 11 deletions
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11
sys/net/pfil.c
View File

@ -34,7 +34,7 @@
#include <sys/errno.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/rwlock.h>
#include <sys/rmlock.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/systm.h>
@ -66,11 +66,12 @@ int
pfil_run_hooks(struct pfil_head *ph, struct mbuf **mp, struct ifnet *ifp,
int dir, struct inpcb *inp)
{
struct rm_priotracker rmpt;
struct packet_filter_hook *pfh;
struct mbuf *m = *mp;
int rv = 0;
PFIL_RLOCK(ph);
PFIL_RLOCK(ph, &rmpt);
KASSERT(ph->ph_nhooks >= 0, ("Pfil hook count dropped < 0"));
for (pfh = pfil_hook_get(dir, ph); pfh != NULL;
pfh = TAILQ_NEXT(pfh, pfil_link)) {
@ -80,7 +81,7 @@ pfil_run_hooks(struct pfil_head *ph, struct mbuf **mp, struct ifnet *ifp,
break;
}
}
PFIL_RUNLOCK(ph);
PFIL_RUNLOCK(ph, &rmpt);
*mp = m;
return (rv);
@ -104,7 +105,7 @@ pfil_head_register(struct pfil_head *ph)
}
PFIL_LIST_UNLOCK();
rw_init(&ph->ph_mtx, "PFil hook read/write mutex");
PFIL_LOCK_INIT(ph);
PFIL_WLOCK(ph);
ph->ph_nhooks = 0;
@ -143,7 +144,7 @@ pfil_head_unregister(struct pfil_head *ph)
free(pfh, M_IFADDR);
TAILQ_FOREACH_SAFE(pfh, &ph->ph_out, pfil_link, pfnext)
free(pfh, M_IFADDR);
rw_destroy(&ph->ph_mtx);
PFIL_LOCK_DESTROY(ph);
return (0);
}

15
sys/net/pfil.h
View File

@ -37,7 +37,7 @@
#include <sys/_lock.h>
#include <sys/_mutex.h>
#include <sys/lock.h>
#include <sys/rwlock.h>
#include <sys/rmlock.h>
struct mbuf;
struct ifnet;
@ -69,7 +69,7 @@ struct pfil_head {
pfil_list_t ph_out;
int ph_type;
int ph_nhooks;
struct rwlock ph_mtx;
struct rmlock ph_lock;
union {
u_long phu_val;
void *phu_ptr;
@ -93,10 +93,13 @@ int pfil_head_unregister(struct pfil_head *);
struct pfil_head *pfil_head_get(int, u_long);
#define PFIL_HOOKED(p) ((p)->ph_nhooks > 0)
#define PFIL_RLOCK(p) rw_rlock(&(p)->ph_mtx)
#define PFIL_WLOCK(p) rw_wlock(&(p)->ph_mtx)
#define PFIL_RUNLOCK(p) rw_runlock(&(p)->ph_mtx)
#define PFIL_WUNLOCK(p) rw_wunlock(&(p)->ph_mtx)
#define PFIL_LOCK_INIT(p) \
rm_init(&(p)->ph_lock, "PFil hook read/write mutex", LO_RECURSABLE)
#define PFIL_LOCK_DESTROY(p) rm_destroy(&(p)->ph_lock)
#define PFIL_RLOCK(p, t) rm_rlock(&(p)->ph_lock, (t))
#define PFIL_WLOCK(p) rm_wlock(&(p)->ph_lock)
#define PFIL_RUNLOCK(p, t) rm_runlock(&(p)->ph_lock, (t))
#define PFIL_WUNLOCK(p) rm_wunlock(&(p)->ph_lock)
#define PFIL_LIST_LOCK() mtx_lock(&pfil_global_lock)
#define PFIL_LIST_UNLOCK() mtx_unlock(&pfil_global_lock)