ftrace: convert ftrace_lock from a spinlock to mutex

Impact: clean up

The older versions of ftrace required doing the ftrace list
search under atomic context. Now all the calls are in non-atomic
context. There is no reason to keep the ftrace_lock as a spinlock.

This patch converts it to a mutex.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>

1 files changed, 19 insertions, 32 deletions

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 45a44c402566..4771732037ee 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -61,7 +61,7 @@ int function_trace_stop;
  */
 static int ftrace_disabled __read_mostly;
 
-static DEFINE_SPINLOCK(ftrace_lock);
+static DEFINE_MUTEX(ftrace_lock);
 static DEFINE_MUTEX(ftrace_sysctl_lock);
 static DEFINE_MUTEX(ftrace_start_lock);
 
@@ -134,8 +134,7 @@ static void ftrace_test_stop_func(unsigned long ip, unsigned long parent_ip)
 
 static int __register_ftrace_function(struct ftrace_ops *ops)
 {
-        /* should not be called from interrupt context */
-        spin_lock(&ftrace_lock);
+        mutex_lock(&ftrace_lock);
 
         ops->next = ftrace_list;
         /*
@@ -172,7 +171,7 @@ static int __register_ftrace_function(struct ftrace_ops *ops)
 #endif
         }
 
-        spin_unlock(&ftrace_lock);
+        mutex_unlock(&ftrace_lock);
 
         return 0;
 }
@@ -182,8 +181,7 @@ static int __unregister_ftrace_function(struct ftrace_ops *ops)
         struct ftrace_ops **p;
         int ret = 0;
 
-        /* should not be called from interrupt context */
-        spin_lock(&ftrace_lock);
+        mutex_lock(&ftrace_lock);
 
         /*
          * If we are removing the last function, then simply point
@@ -224,7 +222,7 @@ static int __unregister_ftrace_function(struct ftrace_ops *ops)
         }
 
  out:
-        spin_unlock(&ftrace_lock);
+        mutex_unlock(&ftrace_lock);
 
         return ret;
 }
@@ -233,8 +231,7 @@ static void ftrace_update_pid_func(void)
 {
         ftrace_func_t func;
 
-        /* should not be called from interrupt context */
-        spin_lock(&ftrace_lock);
+        mutex_lock(&ftrace_lock);
 
         if (ftrace_trace_function == ftrace_stub)
                 goto out;
@@ -256,7 +253,7 @@ static void ftrace_update_pid_func(void)
 #endif
 
  out:
-        spin_unlock(&ftrace_lock);
+        mutex_unlock(&ftrace_lock);
 }
 
 #ifdef CONFIG_DYNAMIC_FTRACE
@@ -358,15 +355,12 @@ void ftrace_release(void *start, unsigned long size)
         if (ftrace_disabled || !start)
                 return;
 
-        /* should not be called from interrupt context */
-        spin_lock(&ftrace_lock);
-
+        mutex_lock(&ftrace_lock);
         do_for_each_ftrace_rec(pg, rec) {
                 if ((rec->ip >= s) && (rec->ip < e))
                         ftrace_free_rec(rec);
         } while_for_each_ftrace_rec();
-
-        spin_unlock(&ftrace_lock);
+        mutex_unlock(&ftrace_lock);
 }
 
 static struct dyn_ftrace *ftrace_alloc_dyn_node(unsigned long ip)
@@ -803,8 +797,7 @@ t_next(struct seq_file *m, void *v, loff_t *pos)
         if (iter->flags & FTRACE_ITER_PRINTALL)
                 return NULL;
 
-        /* should not be called from interrupt context */
-        spin_lock(&ftrace_lock);
+        mutex_lock(&ftrace_lock);
  retry:
         if (iter->idx >= iter->pg->index) {
                 if (iter->pg->next) {
@@ -833,7 +826,7 @@ t_next(struct seq_file *m, void *v, loff_t *pos)
                         goto retry;
                 }
         }
-        spin_unlock(&ftrace_lock);
+        mutex_unlock(&ftrace_lock);
 
         return rec;
 }
@@ -962,8 +955,7 @@ static void ftrace_filter_reset(int enable)
         struct dyn_ftrace *rec;
         unsigned long type = enable ? FTRACE_FL_FILTER : FTRACE_FL_NOTRACE;
 
-        /* should not be called from interrupt context */
-        spin_lock(&ftrace_lock);
+        mutex_lock(&ftrace_lock);
         if (enable)
                 ftrace_filtered = 0;
         do_for_each_ftrace_rec(pg, rec) {
@@ -971,8 +963,7 @@ static void ftrace_filter_reset(int enable)
                         continue;
                 rec->flags &= ~type;
         } while_for_each_ftrace_rec();
-
-        spin_unlock(&ftrace_lock);
+        mutex_unlock(&ftrace_lock);
 }
 
 static int
@@ -1151,8 +1142,7 @@ static void ftrace_match_records(char *buff, int len, int enable)
 
         search_len = strlen(search);
 
-        /* should not be called from interrupt context */
-        spin_lock(&ftrace_lock);
+        mutex_lock(&ftrace_lock);
         do_for_each_ftrace_rec(pg, rec) {
 
                 if (rec->flags & FTRACE_FL_FAILED)
@@ -1171,7 +1161,7 @@ static void ftrace_match_records(char *buff, int len, int enable)
                 if (enable && (rec->flags & FTRACE_FL_FILTER))
                         ftrace_filtered = 1;
         } while_for_each_ftrace_rec();
-        spin_unlock(&ftrace_lock);
+        mutex_unlock(&ftrace_lock);
 }
 
 static int
@@ -1218,8 +1208,7 @@ static void ftrace_match_module_records(char *buff, char *mod, int enable)
                 search_len = strlen(search);
         }
 
-        /* should not be called from interrupt context */
-        spin_lock(&ftrace_lock);
+        mutex_lock(&ftrace_lock);
         do_for_each_ftrace_rec(pg, rec) {
 
                 if (rec->flags & FTRACE_FL_FAILED)
@@ -1236,7 +1225,7 @@ static void ftrace_match_module_records(char *buff, char *mod, int enable)
                         ftrace_filtered = 1;
 
         } while_for_each_ftrace_rec();
-        spin_unlock(&ftrace_lock);
+        mutex_unlock(&ftrace_lock);
 }
 
 /*
@@ -1676,9 +1665,7 @@ ftrace_set_func(unsigned long *array, int idx, char *buffer)
         if (ftrace_disabled)
                 return -ENODEV;
 
-        /* should not be called from interrupt context */
-        spin_lock(&ftrace_lock);
-
+        mutex_lock(&ftrace_lock);
         do_for_each_ftrace_rec(pg, rec) {
 
                 if (rec->flags & (FTRACE_FL_FAILED | FTRACE_FL_FREE))
@@ -1699,7 +1686,7 @@ ftrace_set_func(unsigned long *array, int idx, char *buffer)
                 }
         } while_for_each_ftrace_rec();
  out:
-        spin_unlock(&ftrace_lock);
+        mutex_unlock(&ftrace_lock);
 
         return found ? 0 : -EINVAL;
 }