procfs: allow threads to rename siblings via /proc/pid/tasks/tid/comm

[mv-sheeva.git] / fs / proc / base.c

diff --git a/fs/proc/base.c b/fs/proc/base.c
index af643b5aefe8909e25b1f741ad1b24a5f53f7a81..4df4a464a919c2ed372b4e93d742216d51692066 100644 (file)
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1265,6 +1265,72 @@ static const struct file_operations proc_pid_sched_operations = {
 
 #endif
 
+static ssize_t comm_write(struct file *file, const char __user *buf,
+                               size_t count, loff_t *offset)
+{
+       struct inode *inode = file->f_path.dentry->d_inode;
+       struct task_struct *p;
+       char buffer[TASK_COMM_LEN];
+
+       memset(buffer, 0, sizeof(buffer));
+       if (count > sizeof(buffer) - 1)
+               count = sizeof(buffer) - 1;
+       if (copy_from_user(buffer, buf, count))
+               return -EFAULT;
+
+       p = get_proc_task(inode);
+       if (!p)
+               return -ESRCH;
+
+       if (same_thread_group(current, p))
+               set_task_comm(p, buffer);
+       else
+               count = -EINVAL;
+
+       put_task_struct(p);
+
+       return count;
+}
+
+static int comm_show(struct seq_file *m, void *v)
+{
+       struct inode *inode = m->private;
+       struct task_struct *p;
+
+       p = get_proc_task(inode);
+       if (!p)
+               return -ESRCH;
+
+       task_lock(p);
+       seq_printf(m, "%s\n", p->comm);
+       task_unlock(p);
+
+       put_task_struct(p);
+
+       return 0;
+}
+
+static int comm_open(struct inode *inode, struct file *filp)
+{
+       int ret;
+
+       ret = single_open(filp, comm_show, NULL);
+       if (!ret) {
+               struct seq_file *m = filp->private_data;
+
+               m->private = inode;
+       }
+       return ret;
+}
+
+static const struct file_operations proc_pid_set_comm_operations = {
+       .open           = comm_open,
+       .read           = seq_read,
+       .write          = comm_write,
+       .llseek         = seq_lseek,
+       .release        = single_release,
+};
+
 /*
  * We added or removed a vma mapping the executable. The vmas are only mapped
  * during exec and are not mapped with the mmap system call.
@@ -2504,6 +2570,7 @@ static const struct pid_entry tgid_base_stuff[] = {
 #ifdef CONFIG_SCHED_DEBUG
        REG("sched",      S_IRUGO|S_IWUSR, proc_pid_sched_operations),
 #endif
+       REG("comm",      S_IRUGO|S_IWUSR, proc_pid_set_comm_operations),
 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
        INF("syscall",    S_IRUSR, proc_pid_syscall),
 #endif
@@ -2838,6 +2905,7 @@ static const struct pid_entry tid_base_stuff[] = {
 #ifdef CONFIG_SCHED_DEBUG
        REG("sched",     S_IRUGO|S_IWUSR, proc_pid_sched_operations),
 #endif
+       REG("comm",      S_IRUGO|S_IWUSR, proc_pid_set_comm_operations),
 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
        INF("syscall",   S_IRUSR, proc_pid_syscall),
 #endif