linux-kernel - [PATCH 2/9] um/drivers/vector_user: Less checks in user_init_raw

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Date:   Sun, 11 Mar 2018 16:17:12 +0100
From:   SF Markus Elfring <elfring@...rs.sourceforge.net>
To:     user-mode-linux-devel@...ts.sourceforge.net,
        Anton Ivanov <anton.ivanov@...bridgegreys.com>,
        Jeff Dike <jdike@...toit.com>,
        Richard Weinberger <richard@....at>
Cc:     user-mode-linux-user@...ts.sourceforge.net,
        kernel-janitors@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH 2/9] um/drivers/vector_user: Less checks in
 user_init_raw_fds() after error detection

From: Markus Elfring <elfring@...rs.sourceforge.net>
Date: Sun, 11 Mar 2018 11:40:14 +0100

Up to two checks could be repeated by the user_init_raw_fds() function
during error handling even if the relevant properties can be determined
for the involved variables before by source code analysis.

* Adjust jump targets so that an extra check can be omitted at the end.

* Delete an initialisation for the local variable "rxfd"
  which became unnecessary with this refactoring.

Signed-off-by: Markus Elfring <elfring@...rs.sourceforge.net>
---
 arch/um/drivers/vector_user.c | 61 ++++++++++++++++++++-----------------------
 1 file changed, 28 insertions(+), 33 deletions(-)

diff --git a/arch/um/drivers/vector_user.c b/arch/um/drivers/vector_user.c
index d6a6207d4061..037cd85ee424 100644
--- a/arch/um/drivers/vector_user.c
+++ b/arch/um/drivers/vector_user.c
@@ -207,54 +207,46 @@ static struct vector_fds *user_init_tap_fds(struct arglist *ifspec)
 static struct vector_fds *user_init_raw_fds(struct arglist *ifspec)
 {
 	struct ifreq ifr;
-	int rxfd = -1, txfd = -1;
+	int rxfd, txfd = -1;
 	struct sockaddr_ll sock;
-	int err = -ENOMEM;
-	char *iface;
 	struct vector_fds *result;
 	int optval = 1;
+	int err;
+	char *iface = uml_vector_fetch_arg(ifspec, TOKEN_IFNAME);
 
-
-	iface = uml_vector_fetch_arg(ifspec, TOKEN_IFNAME);
-	if (iface == NULL)
-		goto cleanup;
+	if (!iface) {
+		err = -ENOMEM;
+		goto report_failure;
+	}
 
 	rxfd = socket(AF_PACKET, SOCK_RAW, ETH_P_ALL);
-	if (rxfd == -1) {
-		err = -errno;
-		goto cleanup;
-	}
+	if (rxfd == -1)
+		goto set_error_code;
+
 	txfd = socket(AF_PACKET, SOCK_RAW, 0); /* Turn off RX on this fd */
-	if (txfd == -1) {
-		err = -errno;
-		goto cleanup;
-	}
+	if (txfd == -1)
+		goto set_error_code;
+
 	memset(&ifr, 0, sizeof(ifr));
 	strncpy((char *)&ifr.ifr_name, iface, sizeof(ifr.ifr_name) - 1);
-	if (ioctl(rxfd, SIOCGIFINDEX, (void *) &ifr) < 0) {
-		err = -errno;
-		goto cleanup;
-	}
+	if (ioctl(rxfd, SIOCGIFINDEX, (void *) &ifr) < 0)
+		goto set_error_code;
 
 	sock.sll_family = AF_PACKET;
 	sock.sll_protocol = htons(ETH_P_ALL);
 	sock.sll_ifindex = ifr.ifr_ifindex;
 
-	if (bind(rxfd,
-		(struct sockaddr *) &sock, sizeof(struct sockaddr_ll)) < 0) {
-		err = -errno;
-		goto cleanup;
-	}
+	if (bind(rxfd, (struct sockaddr *)&sock, sizeof(struct sockaddr_ll))
+	    < 0)
+		goto set_error_code;
 
 	sock.sll_family = AF_PACKET;
 	sock.sll_protocol = htons(ETH_P_IP);
 	sock.sll_ifindex = ifr.ifr_ifindex;
 
-	if (bind(txfd,
-		(struct sockaddr *) &sock, sizeof(struct sockaddr_ll)) < 0) {
-		err = -errno;
-		goto cleanup;
-	}
+	if (bind(txfd, (struct sockaddr *)&sock, sizeof(struct sockaddr_ll))
+	    < 0)
+		goto set_error_code;
 
 	if (setsockopt(txfd,
 		SOL_PACKET, PACKET_QDISC_BYPASS,
@@ -270,12 +262,15 @@ static struct vector_fds *user_init_raw_fds(struct arglist *ifspec)
 		result->remote_addr_size = 0;
 	}
 	return result;
-cleanup:
-	printk(UM_KERN_ERR "user_init_raw: init failed, error %d", err);
-	if (rxfd >= 0)
-		os_close_file(rxfd);
+
+set_error_code:
+	err = -errno;
+	os_close_file(rxfd);
+
 	if (txfd >= 0)
 		os_close_file(txfd);
+report_failure:
+	printk(UM_KERN_ERR "%s: init failed: %d", __func__, err);
 	return NULL;
 }
 
-- 
2.16.2