[PATCH 2/9] um/drivers/vector_user: Less checks in user_init_raw_fds() after error detection

[SF Markus Elfring]

From: Markus Elfring <elfr...@users.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 <elfr...@users.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