latencytop: change /proc task_struct access method

Change getting task_struct by get_proc_task() at read or write time,
and returns -ESRCH if get_proc_task() returns NULL.
This is same behavior as other /proc files.

Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 85e06e4980780163740790e9d160a69bab6cfc7e..91a1bd67ac1d6dd58da1d3db5c0691cdb7ea7525 100644 (file)
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -314,9 +314,12 @@ static int proc_pid_schedstat(struct task_struct *task, char *buffer)
 static int lstats_show_proc(struct seq_file *m, void *v)
 {
        int i;
-       struct task_struct *task = m->private;
-       seq_puts(m, "Latency Top version : v0.1\n");
+       struct inode *inode = m->private;
+       struct task_struct *task = get_proc_task(inode);
 
+       if (!task)
+               return -ESRCH;
+       seq_puts(m, "Latency Top version : v0.1\n");
        for (i = 0; i < 32; i++) {
                if (task->latency_record[i].backtrace[0]) {
                        int q;
@@ -341,43 +344,24 @@ static int lstats_show_proc(struct seq_file *m, void *v)
                }
 
        }
+       put_task_struct(task);
        return 0;
 }
 
 static int lstats_open(struct inode *inode, struct file *file)
 {
-       int ret;
-       struct seq_file *m;
-       struct task_struct *task = get_proc_task(inode);
-
-       if (!task)
-               return -ENOENT;
-       ret = single_open(file, lstats_show_proc, NULL);
-       if (!ret) {
-               m = file->private_data;
-               m->private = task;
-       }
-       return ret;
-}
-
-static int lstats_release(struct inode *inode, struct file *file)
-{
-       struct seq_file *m = file->private_data;
-       struct task_struct *task = m->private;
-
-       put_task_struct(task);
-       return single_release(inode, file);
+       return single_open(file, lstats_show_proc, inode);
 }
 
 static ssize_t lstats_write(struct file *file, const char __user *buf,
                            size_t count, loff_t *offs)
 {
-       struct seq_file *m;
-       struct task_struct *task;
+       struct task_struct *task = get_proc_task(file->f_dentry->d_inode);
 
-       m = file->private_data;
-       task = m->private;
+       if (!task)
+               return -ESRCH;
        clear_all_latency_tracing(task);
+       put_task_struct(task);
 
        return count;
 }
@@ -387,7 +371,7 @@ static const struct file_operations proc_lstats_operations = {
        .read           = seq_read,
        .write          = lstats_write,
        .llseek         = seq_lseek,
-       .release        = lstats_release,
+       .release        = single_release,
 };
 
 #endif