[PATCH 8/9] um/drivers/vector_user: Less checks in user_init_tap_fds() after error detection

[SF Markus Elfring]

From: Markus Elfring <elfr...@users.sourceforge.net>
Date: Sun, 11 Mar 2018 15:43:31 +0100

Three checks could be repeated by the user_init_tap_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.

* Delete three sanity checks and an initialisation (for the local
  variable "result") which became unnecessary with this refactoring.

Signed-off-by: Markus Elfring <elfr...@users.sourceforge.net>
---
 arch/um/drivers/vector_user.c | 31 +++++++++++++++----------------
 1 file changed, 15 insertions(+), 16 deletions(-)

diff --git a/arch/um/drivers/vector_user.c b/arch/um/drivers/vector_user.c
index 5e78723c34d4..bd625034a0f0 100644
--- a/arch/um/drivers/vector_user.c
+++ b/arch/um/drivers/vector_user.c
@@ -123,18 +123,18 @@ static struct vector_fds *user_init_tap_fds(struct 
arglist *ifspec)
        struct sockaddr_ll sock;
        int err = -ENOMEM, offload;
        char *iface;
-       struct vector_fds *result = NULL;
+       struct vector_fds *result;
 
        iface = uml_vector_fetch_arg(ifspec, TOKEN_IFNAME);
        if (iface == NULL) {
                printk(UM_KERN_ERR "uml_tap: failed to parse interface spec\n");
-               goto tap_cleanup;
+               goto report_failure;
        }
 
        result = uml_kmalloc(sizeof(struct vector_fds), UM_GFP_KERNEL);
        if (result == NULL) {
                printk(UM_KERN_ERR "uml_tap: failed to allocate file 
descriptors\n");
-               goto tap_cleanup;
+               goto report_failure;
        }
        result->rx_fd = -1;
        result->tx_fd = -1;
@@ -146,7 +146,7 @@ static struct vector_fds *user_init_tap_fds(struct arglist 
*ifspec)
        fd = open(PATH_NET_TUN, O_RDWR);
        if (fd < 0) {
                printk(UM_KERN_ERR "uml_tap: failed to open tun device\n");
-               goto tap_cleanup;
+               goto free_result;
        }
        result->tx_fd = fd;
        memset(&ifr, 0, sizeof(ifr));
@@ -156,7 +156,7 @@ static struct vector_fds *user_init_tap_fds(struct arglist 
*ifspec)
        err = ioctl(fd, TUNSETIFF, (void *) &ifr);
        if (err != 0) {
                printk(UM_KERN_ERR "uml_tap: failed to select tap interface\n");
-               goto tap_cleanup;
+               goto close_tx_fd;
        }
 
        offload = TUN_F_CSUM | TUN_F_TSO4 | TUN_F_TSO6;
@@ -168,7 +168,7 @@ static struct vector_fds *user_init_tap_fds(struct arglist 
*ifspec)
        if (fd == -1) {
                printk(UM_KERN_ERR
                        "uml_tap: failed to create socket: %i\n", -errno);
-               goto tap_cleanup;
+               goto close_tx_fd;
        }
        result->rx_fd = fd;
        memset(&ifr, 0, sizeof(ifr));
@@ -176,7 +176,7 @@ static struct vector_fds *user_init_tap_fds(struct arglist 
*ifspec)
        if (ioctl(fd, SIOCGIFINDEX, (void *) &ifr) < 0) {
                printk(UM_KERN_ERR
                        "uml_tap: failed to set interface: %i\n", -errno);
-               goto tap_cleanup;
+               goto close_rx_fd;
        }
 
        sock.sll_family = AF_PACKET;
@@ -188,18 +188,17 @@ static struct vector_fds *user_init_tap_fds(struct 
arglist *ifspec)
                printk(UM_KERN_ERR
                        "user_init_tap: failed to bind raw pair, err %d\n",
                                -errno);
-               goto tap_cleanup;
+               goto close_rx_fd;
        }
        return result;
-tap_cleanup:
-       if (result != NULL) {
-               if (result->rx_fd >= 0)
-                       os_close_file(result->rx_fd);
-               if (result->tx_fd >= 0)
-                       os_close_file(result->tx_fd);
-               kfree(result);
-       }
 
+close_rx_fd:
+       os_close_file(result->rx_fd);
+close_tx_fd:
+       os_close_file(result->tx_fd);
+free_result:
+       kfree(result);
+report_failure:
        printk(UM_KERN_ERR "%s: init failed: %d", __func__, err);
        return NULL;
 }
-- 
2.16.2