Clean up the fifo_open() implementation:

        Restructure the error handling portion of the resource allocation
        code to eliminate duplicated code.

        Test for the O_NONBLOCK && fi_readers == 0 case before incrementing
        fi_writers and modifying the the socket flag to avoid having to
        undo these operations in this error case.

        Restructure and simplify the code that handles blocking opens.

There should be no change to functionality.

1 files changed, 30 insertions, 45 deletions

diff --git a/sys/fs/fifofs/fifo_vnops.c b/sys/fs/fifofs/fifo_vnops.c
index ef448f7..95c8a9e 100644
--- a/sys/fs/fifofs/fifo_vnops.c
+++ b/sys/fs/fifofs/fifo_vnops.c
@@ -172,40 +172,33 @@ fifo_open(ap)
 	struct vnode *vp = ap->a_vp;
 	struct fifoinfo *fip;
 	struct thread *td = ap->a_td;
+	struct ucred *cred = ap->a_cred;
 	struct socket *rso, *wso;
 	int error;
 
 	if ((fip = vp->v_fifoinfo) == NULL) {
 		MALLOC(fip, struct fifoinfo *, sizeof(*fip), M_VNODE, M_WAITOK);
-		vp->v_fifoinfo = fip;
-		error = socreate(AF_LOCAL, &rso, SOCK_STREAM, 0,
-		    ap->a_td->td_ucred, ap->a_td);
-		if (error) {
-			free(fip, M_VNODE);
-			vp->v_fifoinfo = NULL;
-			return (error);
-		}
+		error = socreate(AF_LOCAL, &rso, SOCK_STREAM, 0, cred, td);
+		if (error)
+			goto fail1;
 		fip->fi_readsock = rso;
-		error = socreate(AF_LOCAL, &wso, SOCK_STREAM, 0,
-		    ap->a_td->td_ucred, ap->a_td);
-		if (error) {
-			(void)soclose(rso);
-			free(fip, M_VNODE);
-			vp->v_fifoinfo = NULL;
-			return (error);
-		}
+		error = socreate(AF_LOCAL, &wso, SOCK_STREAM, 0, cred, td);
+		if (error)
+			goto fail2;
 		fip->fi_writesock = wso;
 		error = unp_connect2(wso, rso);
 		if (error) {
 			(void)soclose(wso);
+fail2:
 			(void)soclose(rso);
+fail1:
 			free(fip, M_VNODE);
-			vp->v_fifoinfo = NULL;
 			return (error);
 		}
 		fip->fi_readers = fip->fi_writers = 0;
 		wso->so_snd.sb_lowat = PIPE_BUF;
 		rso->so_state |= SS_CANTRCVMORE;
+		vp->v_fifoinfo = fip;
 	}
 
 	/*
@@ -233,6 +226,10 @@ fifo_open(ap)
 		}
 	}
 	if (ap->a_mode & FWRITE) {
+		if ((ap->a_mode & O_NONBLOCK) && fip->fi_readers == 0) {
+			VI_UNLOCK(vp);
+			return (ENXIO);
+		}
 		fip->fi_writers++;
 		if (fip->fi_writers == 1) {
 			fip->fi_readsock->so_state &= ~SS_CANTRCVMORE;
@@ -244,8 +241,8 @@ fifo_open(ap)
 			}
 		}
 	}
-	if ((ap->a_mode & FREAD) && (ap->a_mode & O_NONBLOCK) == 0) {
-		if (fip->fi_writers == 0) {
+	if ((ap->a_mode & O_NONBLOCK) == 0) {
+		if ((ap->a_mode & FREAD) && fip->fi_writers == 0) {
 			VOP_UNLOCK(vp, 0, td);
 			error = msleep(&fip->fi_readers, VI_MTX(vp),
 			    PCATCH | PSOCK, "fifoor", 0);
@@ -263,36 +260,24 @@ fifo_open(ap)
 			 * that we must wait for.
 			 */
 		}
-	}
-	if (ap->a_mode & FWRITE) {
-		if (ap->a_mode & O_NONBLOCK) {
-			if (fip->fi_readers == 0) {
-				VI_UNLOCK(vp);
+		if ((ap->a_mode & FWRITE) && fip->fi_readers == 0) {
+			VOP_UNLOCK(vp, 0, td);
+			error = msleep(&fip->fi_writers, VI_MTX(vp),
+			    PCATCH | PSOCK, "fifoow", 0);
+			vn_lock(vp,
+			    LK_EXCLUSIVE | LK_RETRY | LK_INTERLOCK, td);
+			if (error) {
 				fip->fi_writers--;
 				if (fip->fi_writers == 0)
 					socantrcvmore(fip->fi_readsock);
-				return (ENXIO);
-			}
-		} else {
-			if (fip->fi_readers == 0) {
-				VOP_UNLOCK(vp, 0, td);
-				error = msleep(&fip->fi_writers, VI_MTX(vp),
-				    PCATCH | PSOCK, "fifoow", 0);
-				vn_lock(vp,
-				    LK_EXCLUSIVE | LK_RETRY | LK_INTERLOCK, td);
-				if (error) {
-					fip->fi_writers--;
-					if (fip->fi_writers == 0)
-						socantrcvmore(fip->fi_readsock);
-					return (error);
-				}
-				/*
-				 * We must have got woken up because we had
-				 * a reader.  That (and not still having one)
-				 * is the condition that we must wait for.
-				 */
-				return (0);
+				return (error);
 			}
+			/*
+			 * We must have got woken up because we had
+			 * a reader.  That (and not still having one)
+			 * is the condition that we must wait for.
+			 */
+			return (0);
 		}
 	}
 	VI_UNLOCK(vp);