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>

1 files changed, 19 insertions, 10 deletions

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 93245ae046e1..b08996ca561d 100644
--- 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);