- Improve BPF locking model.

Interface locks and descriptor locks are converted from mutex(9) to rwlock(9).
This greately improves performance: in most common case we need to acquire 1
reader lock instead of 2 mutexes.

- Remove filter(descriptor) (reader) lock in bpf_mtap[2]
This was suggested by glebius@. We protect filter by requesting interface
writer lock on filter change.

- Cover struct bpf_if under BPF_INTERNAL define. This permits including bpf.h
without including rwlock stuff. However, this is is temporary solution,
struct bpf_if should be made opaque for any external caller.

Found by:       Dmitrij Tejblum <tejblum@yandex-team.ru>
Sponsored by:   Yandex LLC

Reviewed by:    glebius (previous version)
Reviewed by:    silence on -net@
Approved by:    (mentor)

MFC after:      3 weeks

1 files changed, 3 insertions, 3 deletions

diff --git a/sys/net/bpf_buffer.c b/sys/net/bpf_buffer.c
index d338fca..869e70b 100644
--- a/sys/net/bpf_buffer.c
+++ b/sys/net/bpf_buffer.c
@@ -184,9 +184,9 @@ bpf_buffer_ioctl_sblen(struct bpf_d *d, u_int *i)
 {
 	u_int size;
 
-	BPFD_LOCK(d);
+	BPFD_WLOCK(d);
 	if (d->bd_bif != NULL) {
-		BPFD_UNLOCK(d);
+		BPFD_WUNLOCK(d);
 		return (EINVAL);
 	}
 	size = *i;
@@ -195,7 +195,7 @@ bpf_buffer_ioctl_sblen(struct bpf_d *d, u_int *i)
 	else if (size < BPF_MINBUFSIZE)
 		*i = size = BPF_MINBUFSIZE;
 	d->bd_bufsize = size;
-	BPFD_UNLOCK(d);
+	BPFD_WUNLOCK(d);
 	return (0);
 }