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Make bpf MP-safe 

By the change, bpf_mtap can run without any locks as long as its bpf filter
doesn't match a target packet. Pushing data to a bpf buffer still needs
a lock. Removing the lock requires big changes and it's a future work.

Another known issue is that we need to remain some obsolete variables to
avoid breaking kvm(3) users such as netstat and fstat. One problem for
MP-ification is that in order to keep statistic counters of bpf_d we need
to use atomic operations for them. Once we retire the kvm(3) users, we
should make the counters per-CPU and remove the atomic operations.
This commit is contained in:
ozaki-r 2017-02-09 09:30:26 +00:00
parent 929132b4a7
commit f66c9ca3fd
3 changed files with 287 additions and 159 deletions
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409
sys/net/bpf.c
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File diff suppressed because it is too large Load Diff

21
sys/net/bpfdesc.h
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@ -1,4 +1,4 @@
/* $NetBSD: bpfdesc.h,v 1.43 2017/02/01 08:16:42 ozaki-r Exp $ */
/* $NetBSD: bpfdesc.h,v 1.44 2017/02/09 09:30:26 ozaki-r Exp $ */
/*
* Copyright (c) 1990, 1991, 1993
@ -49,8 +49,15 @@
#include <sys/pslist.h>
#include <sys/mutex.h>
#include <sys/condvar.h>
#include <sys/psref.h>
#endif
struct bpf_filter {
struct bpf_insn *bf_insn; /* filter code */
size_t bf_size;
bpfjit_func_t bf_jitcode; /* compiled filter program */
};
/*
* Descriptor associated with each open bpf file.
*/
@ -76,7 +83,12 @@ struct bpf_d {
struct bpf_if * bd_bif; /* interface descriptor */
u_long bd_rtout; /* Read timeout in 'ticks' */
struct bpf_insn *bd_filter; /* filter code */
/* DEPRECATED. Keep it to avoid breaking kvm(3) users */
struct bpf_insn *_bd_filter; /* filter code */
/*
* XXX we should make the counters per-CPU once we retire kvm(3) users
* that directly access them.
*/
u_long bd_rcount; /* number of packets received */
u_long bd_dcount; /* number of packets dropped */
u_long bd_ccount; /* number of packets captured */
@ -108,12 +120,14 @@ struct bpf_d {
#ifdef _LP64
int bd_compat32; /* 32-bit stream on LP64 system */
#endif
/* DEPRECATED. Keep it to avoid breaking kvm(3) users */
bpfjit_func_t bd_jitcode; /* compiled filter program */
size_t bd_filter_size;
struct bpf_filter *bd_filter;
#ifdef _KERNEL
struct pslist_entry bd_bif_dlist_entry; /* For bpf_if */
struct pslist_entry bd_bpf_dlist_entry; /* For the global list */
kmutex_t *bd_mtx;
kmutex_t *bd_buf_mtx;
kcondvar_t bd_cv;
#endif
};
@ -160,6 +174,7 @@ struct bpf_if {
#ifdef _KERNEL
struct pslist_entry bif_iflist_entry;
struct pslist_head bif_dlist_head;
struct psref_target bif_psref;
#endif
};

16
sys/net/if.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: if.c,v 1.375 2017/01/25 03:04:21 christos Exp $ */
/* $NetBSD: if.c,v 1.376 2017/02/09 09:30:26 ozaki-r Exp $ */
/*-
* Copyright (c) 1999, 2000, 2001, 2008 The NetBSD Foundation, Inc.
@ -90,7 +90,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: if.c,v 1.375 2017/01/25 03:04:21 christos Exp $");
__KERNEL_RCSID(0, "$NetBSD: if.c,v 1.376 2017/02/09 09:30:26 ozaki-r Exp $");
#if defined(_KERNEL_OPT)
#include "opt_inet.h"
@ -774,13 +774,7 @@ if_percpuq_softint(void *arg)
while ((m = if_percpuq_dequeue(ipq)) != NULL) {
ifp->if_ipackets++;
#ifndef NET_MPSAFE
KERNEL_LOCK(1, NULL);
#endif
bpf_mtap(ifp, m);
#ifndef NET_MPSAFE
KERNEL_UNLOCK_ONE(NULL);
#endif
ifp->_if_input(ifp, m);
}
@ -1072,13 +1066,7 @@ if_input(struct ifnet *ifp, struct mbuf *m)
KASSERT(!cpu_intr_p());
ifp->if_ipackets++;
#ifndef NET_MPSAFE
KERNEL_LOCK(1, NULL);
#endif
bpf_mtap(ifp, m);
#ifndef NET_MPSAFE
KERNEL_UNLOCK_ONE(NULL);
#endif
ifp->_if_input(ifp, m);
}