ftrace: add ftrace warn on to disable ftrace

Add ftrace warn on to disable ftrace as well as report a warning.

[ Thanks to Andrew Morton for suggesting using the WARN_ON return value ]

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 93245ae046e1b41d57ea5ac96323f8c8db3bdd22..b08996ca561ddaab57397fe3e3806739f0e71a5d 100644 (file)
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -32,6 +32,18 @@
 
 #include "trace.h"
 
+#define FTRACE_WARN_ON(cond)                   \
+       do {                                    \
+               if (WARN_ON(cond))              \
+                       ftrace_kill();          \
+       } while (0)
+
+#define FTRACE_WARN_ON_ONCE(cond)              \
+       do {                                    \
+               if (WARN_ON_ONCE(cond))         \
+                       ftrace_kill();          \
+       } while (0)
+
 /* ftrace_enabled is a method to turn ftrace on or off */
 int ftrace_enabled __read_mostly;
 static int last_ftrace_enabled;
@@ -363,10 +375,8 @@ static struct dyn_ftrace *ftrace_alloc_dyn_node(unsigned long ip)
                rec = ftrace_free_records;
 
                if (unlikely(!(rec->flags & FTRACE_FL_FREE))) {
-                       WARN_ON_ONCE(1);
+                       FTRACE_WARN_ON_ONCE(1);
                        ftrace_free_records = NULL;
-                       ftrace_disabled = 1;
-                       ftrace_enabled = 0;
                        return NULL;
                }
 
@@ -415,7 +425,7 @@ ftrace_record_ip(unsigned long ip)
 
        key = hash_long(ip, FTRACE_HASHBITS);
 
-       WARN_ON_ONCE(key >= FTRACE_HASHSIZE);
+       FTRACE_WARN_ON_ONCE(key >= FTRACE_HASHSIZE);
 
        if (ftrace_ip_in_hash(ip, key))
                goto out;
@@ -607,12 +617,12 @@ ftrace_code_disable(struct dyn_ftrace *rec)
        if (ret) {
                switch (ret) {
                case -EFAULT:
-                       WARN_ON_ONCE(1);
+                       FTRACE_WARN_ON_ONCE(1);
                        pr_info("ftrace faulted on modifying ");
                        print_ip_sym(ip);
                        break;
                case -EINVAL:
-                       WARN_ON_ONCE(1);
+                       FTRACE_WARN_ON_ONCE(1);
                        pr_info("ftrace failed to modify ");
                        print_ip_sym(ip);
                        print_ip_ins(" expected: ", call);
@@ -621,12 +631,12 @@ ftrace_code_disable(struct dyn_ftrace *rec)
                        printk(KERN_CONT "\n");
                        break;
                case -EPERM:
-                       WARN_ON_ONCE(1);
+                       FTRACE_WARN_ON_ONCE(1);
                        pr_info("ftrace faulted on writing ");
                        print_ip_sym(ip);
                        break;
                default:
-                       WARN_ON_ONCE(1);
+                       FTRACE_WARN_ON_ONCE(1);
                        pr_info("ftrace faulted on unknown error ");
                        print_ip_sym(ip);
                }
@@ -1722,8 +1732,7 @@ static int ftraced(void *ignore)
                                        ftrace_update_cnt != 1 ? "s" : "",
                                        ftrace_update_tot_cnt,
                                        usecs, usecs != 1 ? "s" : "");
-                               ftrace_disabled = 1;
-                               WARN_ON_ONCE(1);
+                               FTRACE_WARN_ON_ONCE(1);
                        }
                }
                mutex_unlock(&ftraced_lock);