tracing: Use strim() to remove whitespace instead of doing it manually

The tracing_set_trace_write() function just removes the trailing whitespace
from the user supplied tracer name, but the leading whitespace should also
be removed.

In addition, if the user supplied tracer name contains only a few
whitespace characters, the first one will not be removed using the current
method, which results it a single whitespace character left in the buf.

To fix all of these issues, we use strim() to correctly remove both the
leading and trailing whitespace.

Link: https://lkml.kernel.org/r/20220121095623.1826679-1-ytcoode@gmail.com
Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 087740f..498ae22 100644 (file)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -6461,7 +6461,7 @@ tracing_set_trace_write(struct file *filp, const char __user *ubuf,
 {
        struct trace_array *tr = filp->private_data;
        char buf[MAX_TRACER_SIZE+1];
-       int i;
+       char *name;
        size_t ret;
        int err;
 
@@ -6475,11 +6475,9 @@ tracing_set_trace_write(struct file *filp, const char __user *ubuf,
 
        buf[cnt] = 0;
 
-       /* strip ending whitespace. */
-       for (i = cnt - 1; i > 0 && isspace(buf[i]); i--)
-               buf[i] = 0;
+       name = strim(buf);
 
-       err = tracing_set_tracer(tr, buf);
+       err = tracing_set_tracer(tr, name);
        if (err)
                return err;