printk: Remove unnecessary kmalloc() from syslog during clear

When the request is only for clearing logs, there is no need for
allocation/deallocation. Only the indexes need to be reset and returned.
Rest of the patch is mostly made up of changes because of indention.

Link: http://lkml.kernel.org/r/20180620135951epcas5p3bd2a8f25ec689ca333bce861b527dba2~54wyKcT0_3155531555epcas5p3y@epcas5p3.samsung.com
Cc: linux-kernel@vger.kernel.org
Cc: pankaj.m@samsung.com
Cc: a.sahrawat@samsung.com
Signed-off-by: Namit Gupta <gupta.namit@samsung.com>
Signed-off-by: Himanshu Maithani <himanshu.m@samsung.com>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>

1 files changed, 58 insertions, 51 deletions

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 3999c295d6f7..16b02cc51a14 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -1352,71 +1352,78 @@ static int syslog_print_all(char __user *buf, int size, bool clear)
 {
         char *text;
         int len = 0;
+        u64 next_seq;
+        u64 seq;
+        u32 idx;
+
+        if (!buf) {
+                if (clear) {
+                        logbuf_lock_irq();
+                        clear_seq = log_next_seq;
+                        clear_idx = log_next_idx;
+                        logbuf_unlock_irq();
+                }
+                return 0;
+        }
 
         text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL);
         if (!text)
                 return -ENOMEM;
 
         logbuf_lock_irq();
-        if (buf) {
-                u64 next_seq;
-                u64 seq;
-                u32 idx;
+        /*
+         * Find first record that fits, including all following records,
+         * into the user-provided buffer for this dump.
+         */
+        seq = clear_seq;
+        idx = clear_idx;
+        while (seq < log_next_seq) {
+                struct printk_log *msg = log_from_idx(idx);
 
-                /*
-                 * Find first record that fits, including all following records,
-                 * into the user-provided buffer for this dump.
-                 */
-                seq = clear_seq;
-                idx = clear_idx;
-                while (seq < log_next_seq) {
-                        struct printk_log *msg = log_from_idx(idx);
-
-                        len += msg_print_text(msg, true, NULL, 0);
-                        idx = log_next(idx);
-                        seq++;
-                }
+                len += msg_print_text(msg, true, NULL, 0);
+                idx = log_next(idx);
+                seq++;
+        }
 
-                /* move first record forward until length fits into the buffer */
-                seq = clear_seq;
-                idx = clear_idx;
-                while (len > size && seq < log_next_seq) {
-                        struct printk_log *msg = log_from_idx(idx);
+        /* move first record forward until length fits into the buffer */
+        seq = clear_seq;
+        idx = clear_idx;
+        while (len > size && seq < log_next_seq) {
+                struct printk_log *msg = log_from_idx(idx);
 
-                        len -= msg_print_text(msg, true, NULL, 0);
-                        idx = log_next(idx);
-                        seq++;
-                }
+                len -= msg_print_text(msg, true, NULL, 0);
+                idx = log_next(idx);
+                seq++;
+        }
 
-                /* last message fitting into this dump */
-                next_seq = log_next_seq;
+        /* last message fitting into this dump */
+        next_seq = log_next_seq;
 
-                len = 0;
-                while (len >= 0 && seq < next_seq) {
-                        struct printk_log *msg = log_from_idx(idx);
-                        int textlen;
+        len = 0;
+        while (len >= 0 && seq < next_seq) {
+                struct printk_log *msg = log_from_idx(idx);
+                int textlen;
 
-                        textlen = msg_print_text(msg, true, text,
-                                                 LOG_LINE_MAX + PREFIX_MAX);
-                        if (textlen < 0) {
-                                len = textlen;
-                                break;
-                        }
-                        idx = log_next(idx);
-                        seq++;
+                textlen = msg_print_text(msg, true, text,
+                                         LOG_LINE_MAX + PREFIX_MAX);
+                if (textlen < 0) {
+                        len = textlen;
+                        break;
+                }
+                idx = log_next(idx);
+                seq++;
 
-                        logbuf_unlock_irq();
-                        if (copy_to_user(buf + len, text, textlen))
-                                len = -EFAULT;
-                        else
-                                len += textlen;
-                        logbuf_lock_irq();
+                logbuf_unlock_irq();
+                if (copy_to_user(buf + len, text, textlen))
+                        len = -EFAULT;
+                else
+                        len += textlen;
+                logbuf_lock_irq();
 
-                        if (seq < log_first_seq) {
-                                /* messages are gone, move to next one */
-                                seq = log_first_seq;
-                                idx = log_first_idx;
-                        }
+                if (seq < log_first_seq) {
+                        /* messages are gone, move to next one */
+                        seq = log_first_seq;
+                        idx = log_first_idx;
                 }
         }