printk: Clean up do_syslog() error handling

The error variable in do_syslog() is preemptively set to the error code
before the error condition is checked, and then set to 0 if the error
condition is not encountered. This is not necessary, as it is likely
simpler to return immediately upon encountering the error condition. A
redundant set of the error variable to 0 is also removed.

This patch has been build-tested on x86_64, but not tested for
functionality.

Link: http://lkml.kernel.org/r/20170730033636.GA935@vostro
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Nikitas Angelinas <nikitas.angelinas@gmail.com>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 87f1a8f..cfd9ab1 100644 (file)
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -1435,7 +1435,7 @@ int do_syslog(int type, char __user *buf, int len, int source)
 
        error = check_syslog_permissions(type, source);
        if (error)
-               goto out;
+               return error;
 
        switch (type) {
        case SYSLOG_ACTION_CLOSE:       /* Close log */
@@ -1443,20 +1443,16 @@ int do_syslog(int type, char __user *buf, int len, int source)
        case SYSLOG_ACTION_OPEN:        /* Open log */
                break;
        case SYSLOG_ACTION_READ:        /* Read from log */
-               error = -EINVAL;
                if (!buf || len < 0)
-                       goto out;
-               error = 0;
+                       return -EINVAL;
                if (!len)
-                       goto out;
-               if (!access_ok(VERIFY_WRITE, buf, len)) {
-                       error = -EFAULT;
-                       goto out;
-               }
+                       return 0;
+               if (!access_ok(VERIFY_WRITE, buf, len))
+                       return -EFAULT;
                error = wait_event_interruptible(log_wait,
                                                 syslog_seq != log_next_seq);
                if (error)
-                       goto out;
+                       return error;
                error = syslog_print(buf, len);
                break;
        /* Read/clear last kernel messages */
@@ -1465,16 +1461,12 @@ int do_syslog(int type, char __user *buf, int len, int source)
                /* FALL THRU */
        /* Read last kernel messages */
        case SYSLOG_ACTION_READ_ALL:
-               error = -EINVAL;
                if (!buf || len < 0)
-                       goto out;
-               error = 0;
+                       return -EINVAL;
                if (!len)
-                       goto out;
-               if (!access_ok(VERIFY_WRITE, buf, len)) {
-                       error = -EFAULT;
-                       goto out;
-               }
+                       return 0;
+               if (!access_ok(VERIFY_WRITE, buf, len))
+                       return -EFAULT;
                error = syslog_print_all(buf, len, clear);
                break;
        /* Clear ring buffer */
@@ -1496,15 +1488,13 @@ int do_syslog(int type, char __user *buf, int len, int source)
                break;
        /* Set level of messages printed to console */
        case SYSLOG_ACTION_CONSOLE_LEVEL:
-               error = -EINVAL;
                if (len < 1 || len > 8)
-                       goto out;
+                       return -EINVAL;
                if (len < minimum_console_loglevel)
                        len = minimum_console_loglevel;
                console_loglevel = len;
                /* Implicitly re-enable logging to console */
                saved_console_loglevel = LOGLEVEL_DEFAULT;
-               error = 0;
                break;
        /* Number of chars in the log buffer */
        case SYSLOG_ACTION_SIZE_UNREAD:
@@ -1526,7 +1516,6 @@ int do_syslog(int type, char __user *buf, int len, int source)
                        u64 seq = syslog_seq;
                        u32 idx = syslog_idx;
 
-                       error = 0;
                        while (seq < log_next_seq) {
                                struct printk_log *msg = log_from_idx(idx);
 
@@ -1546,7 +1535,7 @@ int do_syslog(int type, char __user *buf, int len, int source)
                error = -EINVAL;
                break;
        }
-out:
+
        return error;
 }