Introduce fd_iterfile() a new helper function to iterate over `filehead'.

This turns `filehead' into a local variable, that will make it easier
to protect it.

ok visa@

4 files changed, 31 insertions, 22 deletions

diff --git a/sys/kern/kern_descrip.c b/sys/kern/kern_descrip.c
index 863ee824c19..100d86f4c49 100644
--- a/sys/kern/kern_descrip.c
+++ b/sys/kern/kern_descrip.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: kern_descrip.c,v 1.151 2018/04/18 09:59:09 mpi Exp $	*/
+/*	$OpenBSD: kern_descrip.c,v 1.152 2018/04/25 10:29:16 mpi Exp $	*/
 /*	$NetBSD: kern_descrip.c,v 1.42 1996/03/30 22:24:38 christos Exp $	*/
 
 /*
@@ -180,6 +180,28 @@ fd_unused(struct filedesc *fdp, int fd)
 }
 
 struct file *
+fd_iterfile(struct file *fp, struct proc *p)
+{
+	struct file *nfp;
+
+	if (fp == NULL)
+		nfp = LIST_FIRST(&filehead);
+	else
+		nfp = LIST_NEXT(fp, f_list);
+
+	/* don't FREF when f_count == 0 to avoid race in fdrop() */
+	while (nfp != NULL && nfp->f_count == 0)
+		nfp = LIST_NEXT(nfp, f_list);
+	if (nfp != NULL)
+		FREF(nfp);
+
+	if (fp != NULL)
+		FRELE(fp, p);
+
+	return nfp;
+}
+
+struct file *
 fd_getfile(struct filedesc *fdp, int fd)
 {
 	struct file *fp;
diff --git a/sys/kern/kern_sysctl.c b/sys/kern/kern_sysctl.c
index c98f9d53d72..8299f50be6a 100644
--- a/sys/kern/kern_sysctl.c
+++ b/sys/kern/kern_sysctl.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: kern_sysctl.c,v 1.332 2018/02/19 08:59:52 mpi Exp $	*/
+/*	$OpenBSD: kern_sysctl.c,v 1.333 2018/04/25 10:29:16 mpi Exp $	*/
 /*	$NetBSD: kern_sysctl.c,v 1.17 1996/05/20 17:49:05 mrg Exp $	*/
 
 /*-
@@ -1250,7 +1250,7 @@ sysctl_file(int *name, u_int namelen, char *where, size_t *sizep,
 {
 	struct kinfo_file *kf;
 	struct filedesc *fdp;
-	struct file *fp, *nfp;
+	struct file *fp;
 	struct process *pr;
 	size_t buflen, elem_size, elem_count, outsize;
 	char *dp = where;
@@ -1318,14 +1318,8 @@ sysctl_file(int *name, u_int namelen, char *where, size_t *sizep,
 #endif
 			NET_UNLOCK();
 		}
-		fp = LIST_FIRST(&filehead);
-		/* don't FREF when f_count == 0 to avoid race in fdrop() */
-		while (fp != NULL && fp->f_count == 0)
-			fp = LIST_NEXT(fp, f_list);
-		if (fp == NULL)
-			break;
-		FREF(fp);
-		do {
+		fp = NULL;
+		while ((fp = fd_iterfile(fp, p)) != NULL) {
 			if (fp->f_count > 1 && /* 0, +1 for our FREF() */
 			    FILE_IS_USABLE(fp) &&
 			    (arg == 0 || fp->f_type == arg)) {
@@ -1339,14 +1333,7 @@ sysctl_file(int *name, u_int namelen, char *where, size_t *sizep,
 				if (!skip)
 					FILLIT(fp, NULL, 0, NULL, NULL);
 			}
-			nfp = LIST_NEXT(fp, f_list);
-			while (nfp != NULL && nfp->f_count == 0)
-				nfp = LIST_NEXT(nfp, f_list);
-			if (nfp != NULL)
-				FREF(nfp);
-			FRELE(fp, p);
-			fp = nfp;
-		} while (fp != NULL);
+		}
 		break;
 	case KERN_FILE_BYPID:
 		/* A arg of -1 indicates all processes */
diff --git a/sys/sys/file.h b/sys/sys/file.h
index ef27cd5cc15..62985415f8f 100644
--- a/sys/sys/file.h
+++ b/sys/sys/file.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: file.h,v 1.40 2018/02/10 05:24:23 deraadt Exp $	*/
+/*	$OpenBSD: file.h,v 1.41 2018/04/25 10:29:16 mpi Exp $	*/
 /*	$NetBSD: file.h,v 1.11 1995/03/26 20:24:13 jtc Exp $	*/
 
 /*
@@ -106,7 +106,6 @@ struct file {
 int	fdrop(struct file *, struct proc *);
 
 LIST_HEAD(filelist, file);
-extern struct filelist filehead;	/* head of list of open files */
 extern int maxfiles;			/* kernel limit on number of open files */
 extern int numfiles;			/* actual number of open files */
 extern struct fileops vnops;		/* vnode operations for files */
diff --git a/sys/sys/filedesc.h b/sys/sys/filedesc.h
index 8fd0dc38efc..39486fafd60 100644
--- a/sys/sys/filedesc.h
+++ b/sys/sys/filedesc.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: filedesc.h,v 1.34 2017/02/11 19:51:06 guenther Exp $	*/
+/*	$OpenBSD: filedesc.h,v 1.35 2018/04/25 10:29:17 mpi Exp $	*/
 /*	$NetBSD: filedesc.h,v 1.14 1996/04/09 20:55:28 cgd Exp $	*/
 
 /*
@@ -133,6 +133,7 @@ void	fdfree(struct proc *p);
 int	fdrelease(struct proc *p, int);
 void	fdremove(struct filedesc *, int);
 void	fdcloseexec(struct proc *);
+struct file *fd_iterfile(struct file *, struct proc *);
 struct file *fd_getfile(struct filedesc *, int);
 struct file *fd_getfile_mode(struct filedesc *, int, int);