tracing: Move the pid_list seq_file functions to be global

To allow other aspects of ftrace to use the pid_list logic, we need to reuse
the seq_file functions. Making the generic part into functions that can be
called by other files will help in this regard.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

3 files changed, 77 insertions, 31 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 0b87fe8e6d0b..7943e306cc7f 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -397,6 +397,77 @@ void trace_filter_add_remove_task(struct trace_pid_list *pid_list,
                 clear_bit(task->pid, pid_list->pids);
 }
 
+/**
+ * trace_pid_next - Used for seq_file to get to the next pid of a pid_list
+ * @pid_list: The pid list to show
+ * @v: The last pid that was shown (+1 the actual pid to let zero be displayed)
+ * @pos: The position of the file
+ *
+ * This is used by the seq_file "next" operation to iterate the pids
+ * listed in a trace_pid_list structure.
+ *
+ * Returns the pid+1 as we want to display pid of zero, but NULL would
+ * stop the iteration.
+ */
+void *trace_pid_next(struct trace_pid_list *pid_list, void *v, loff_t *pos)
+{
+        unsigned long pid = (unsigned long)v;
+
+        (*pos)++;
+
+        /* pid already is +1 of the actual prevous bit */
+        pid = find_next_bit(pid_list->pids, pid_list->pid_max, pid);
+
+        /* Return pid + 1 to allow zero to be represented */
+        if (pid < pid_list->pid_max)
+                return (void *)(pid + 1);
+
+        return NULL;
+}
+
+/**
+ * trace_pid_start - Used for seq_file to start reading pid lists
+ * @pid_list: The pid list to show
+ * @pos: The position of the file
+ *
+ * This is used by seq_file "start" operation to start the iteration
+ * of listing pids.
+ *
+ * Returns the pid+1 as we want to display pid of zero, but NULL would
+ * stop the iteration.
+ */
+void *trace_pid_start(struct trace_pid_list *pid_list, loff_t *pos)
+{
+        unsigned long pid;
+        loff_t l = 0;
+
+        pid = find_first_bit(pid_list->pids, pid_list->pid_max);
+        if (pid >= pid_list->pid_max)
+                return NULL;
+
+        /* Return pid + 1 so that zero can be the exit value */
+        for (pid++; pid && l < *pos;
+             pid = (unsigned long)trace_pid_next(pid_list, (void *)pid, &l))
+                ;
+        return (void *)pid;
+}
+
+/**
+ * trace_pid_show - show the current pid in seq_file processing
+ * @m: The seq_file structure to write into
+ * @v: A void pointer of the pid (+1) value to display
+ *
+ * Can be directly used by seq_file operations to display the current
+ * pid value.
+ */
+int trace_pid_show(struct seq_file *m, void *v)
+{
+        unsigned long pid = (unsigned long)v - 1;
+
+        seq_printf(m, "%lu\n", pid);
+        return 0;
+}
+
 static cycle_t buffer_ftrace_now(struct trace_buffer *buf, int cpu)
 {
         u64 ts;
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 172330891c6d..45442d5842f2 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -636,6 +636,9 @@ bool trace_ignore_this_task(struct trace_pid_list *filtered_pids,
 void trace_filter_add_remove_task(struct trace_pid_list *pid_list,
                                   struct task_struct *self,
                                   struct task_struct *task);
+void *trace_pid_next(struct trace_pid_list *pid_list, void *v, loff_t *pos);
+void *trace_pid_start(struct trace_pid_list *pid_list, loff_t *pos);
+int trace_pid_show(struct seq_file *m, void *v);
 
 #ifdef CONFIG_TRACER_MAX_TRACE
 void update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu);
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index a11e6d9a3841..fd831a972bae 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -983,18 +983,8 @@ p_next(struct seq_file *m, void *v, loff_t *pos)
 {
         struct trace_array *tr = m->private;
         struct trace_pid_list *pid_list = rcu_dereference_sched(tr->filtered_pids);
-        unsigned long pid = (unsigned long)v;
 
-        (*pos)++;
-
-        /* pid already is +1 of the actual prevous bit */
-        pid = find_next_bit(pid_list->pids, pid_list->pid_max, pid);
-
-        /* Return pid + 1 to allow zero to be represented */
-        if (pid < pid_list->pid_max)
-                return (void *)(pid + 1);
-
-        return NULL;
+        return trace_pid_next(pid_list, v, pos);
 }
 
 static void *p_start(struct seq_file *m, loff_t *pos)
@@ -1002,8 +992,6 @@ static void *p_start(struct seq_file *m, loff_t *pos)
 {
         struct trace_pid_list *pid_list;
         struct trace_array *tr = m->private;
-        unsigned long pid;
-        loff_t l = 0;
 
         /*
          * Grab the mutex, to keep calls to p_next() having the same
@@ -1019,15 +1007,7 @@ static void *p_start(struct seq_file *m, loff_t *pos)
         if (!pid_list)
                 return NULL;
 
-        pid = find_first_bit(pid_list->pids, pid_list->pid_max);
-        if (pid >= pid_list->pid_max)
-                return NULL;
-
-        /* Return pid + 1 so that zero can be the exit value */
-        for (pid++; pid && l < *pos;
-             pid = (unsigned long)p_next(m, (void *)pid, &l))
-                ;
-        return (void *)pid;
+        return trace_pid_start(pid_list, pos);
 }
 
 static void p_stop(struct seq_file *m, void *p)
@@ -1037,14 +1017,6 @@ static void p_stop(struct seq_file *m, void *p)
         mutex_unlock(&event_mutex);
 }
 
-static int p_show(struct seq_file *m, void *v)
-{
-        unsigned long pid = (unsigned long)v - 1;
-
-        seq_printf(m, "%lu\n", pid);
-        return 0;
-}
-
 static ssize_t
 event_enable_read(struct file *filp, char __user *ubuf, size_t cnt,
                   loff_t *ppos)
@@ -1795,7 +1767,7 @@ static const struct seq_operations show_set_event_seq_ops = {
 static const struct seq_operations show_set_pid_seq_ops = {
         .start = p_start,
         .next = p_next,
-        .show = p_show,
+        .show = trace_pid_show,
         .stop = p_stop,
 };