1 files changed, 13 insertions, 8 deletions

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 1f3ec2afa511..25edd5cc5935 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1662,7 +1662,7 @@ ftrace_regex_open(struct inode *inode, struct file *file, int enable)
 
         mutex_lock(&ftrace_regex_lock);
         if ((file->f_mode & FMODE_WRITE) &&
-            !(file->f_flags & O_APPEND))
+            (file->f_flags & O_TRUNC))
                 ftrace_filter_reset(enable);
 
         if (file->f_mode & FMODE_READ) {
@@ -2278,7 +2278,11 @@ ftrace_regex_write(struct file *file, const char __user *ubuf,
         read++;
         cnt--;
 
-        if (!(iter->flags & ~FTRACE_ITER_CONT)) {
+        /*
+         * If the parser haven't finished with the last write,
+         * continue reading the user input without skipping spaces.
+         */
+        if (!(iter->flags & FTRACE_ITER_CONT)) {
                 /* skip white space */
                 while (cnt && isspace(ch)) {
                         ret = get_user(ch, ubuf++);
@@ -2288,8 +2292,9 @@ ftrace_regex_write(struct file *file, const char __user *ubuf,
                         cnt--;
                 }
 
+                /* only spaces were written */
                 if (isspace(ch)) {
-                        file->f_pos += read;
+                        *ppos += read;
                         ret = read;
                         goto out;
                 }
@@ -2319,12 +2324,12 @@ ftrace_regex_write(struct file *file, const char __user *ubuf,
                 if (ret)
                         goto out;
                 iter->buffer_idx = 0;
-        } else
+        } else {
                 iter->flags |= FTRACE_ITER_CONT;
+                iter->buffer[iter->buffer_idx++] = ch;
+        }
 
-
-        file->f_pos += read;
-
+        *ppos += read;
         ret = read;
  out:
         mutex_unlock(&ftrace_regex_lock);
@@ -2577,7 +2582,7 @@ ftrace_graph_open(struct inode *inode, struct file *file)
 
         mutex_lock(&graph_lock);
         if ((file->f_mode & FMODE_WRITE) &&
-            !(file->f_flags & O_APPEND)) {
+            (file->f_flags & O_TRUNC)) {
                 ftrace_graph_count = 0;
                 memset(ftrace_graph_funcs, 0, sizeof(ftrace_graph_funcs));
         }