[PATCH 09/14] tracing/string: Create and use __free(argv_free) in trace_dynevent.c

[Steven Rostedt]

From: Steven Rostedt <rost...@goodmis.org>

The function dyn_event_release() uses argv_split() which must be freed via
argv_free(). It contains several error paths that do a goto out to call
argv_free() for cleanup. This makes the code complex and error prone.

Create a new __free() directive __free(argv_free) that will call
argv_free() for data allocated with argv_split(), and use it in the
dyn_event_release() function.

Cc: Kees Cook <k...@kernel.org>
Cc: Andy Shevchenko <a...@kernel.org>
Cc: linux-harden...@vger.kernel.org
Signed-off-by: Steven Rostedt (Google) <rost...@goodmis.org>
---
 include/linux/string.h        |  3 +++
 kernel/trace/trace_dynevent.c | 23 +++++++----------------
 2 files changed, 10 insertions(+), 16 deletions(-)

diff --git a/include/linux/string.h b/include/linux/string.h
index 493ac4862c77..c995f973a59a 100644
--- a/include/linux/string.h
+++ b/include/linux/string.h
@@ -10,6 +10,7 @@
 #include <linux/err.h>         /* for ERR_PTR() */
 #include <linux/errno.h>       /* for E2BIG */
 #include <linux/overflow.h>    /* for check_mul_overflow() */
+#include <linux/cleanup.h>     /* for DEFINE_FREE() */
 #include <linux/stdarg.h>
 #include <uapi/linux/string.h>
 
@@ -312,6 +313,8 @@ extern void *kmemdup_array(const void *src, size_t count, 
size_t element_size, g
 extern char **argv_split(gfp_t gfp, const char *str, int *argcp);
 extern void argv_free(char **argv);
 
+DEFINE_FREE(argv_free, char **, if (!IS_ERR_OR_NULL(_T)) argv_free(_T))
+
 /* lib/cmdline.c */
 extern int get_option(char **str, int *pint);
 extern char *get_options(const char *str, int nints, int *ints);
diff --git a/kernel/trace/trace_dynevent.c b/kernel/trace/trace_dynevent.c
index 4376887e0d8a..a322e4f249a5 100644
--- a/kernel/trace/trace_dynevent.c
+++ b/kernel/trace/trace_dynevent.c
@@ -74,24 +74,19 @@ int dyn_event_release(const char *raw_command, struct 
dyn_event_operations *type
        struct dyn_event *pos, *n;
        char *system = NULL, *event, *p;
        int argc, ret = -ENOENT;
-       char **argv;
+       char **argv __free(argv_free) = argv_split(GFP_KERNEL, raw_command, 
&argc);
 
-       argv = argv_split(GFP_KERNEL, raw_command, &argc);
        if (!argv)
                return -ENOMEM;
 
        if (argv[0][0] == '-') {
-               if (argv[0][1] != ':') {
-                       ret = -EINVAL;
-                       goto out;
-               }
+               if (argv[0][1] != ':')
+                       return -EINVAL;
                event = &argv[0][2];
        } else {
                event = strchr(argv[0], ':');
-               if (!event) {
-                       ret = -EINVAL;
-                       goto out;
-               }
+               if (!event)
+                       return -EINVAL;
                event++;
        }
 
@@ -101,10 +96,8 @@ int dyn_event_release(const char *raw_command, struct 
dyn_event_operations *type
                event = p + 1;
                *p = '\0';
        }
-       if (!system && event[0] == '\0') {
-               ret = -EINVAL;
-               goto out;
-       }
+       if (!system && event[0] == '\0')
+               return -EINVAL;
 
        mutex_lock(&event_mutex);
        for_each_dyn_event_safe(pos, n) {
@@ -120,8 +113,6 @@ int dyn_event_release(const char *raw_command, struct 
dyn_event_operations *type
        }
        tracing_reset_all_online_cpus();
        mutex_unlock(&event_mutex);
-out:
-       argv_free(argv);
        return ret;
 }
 
-- 
2.45.2