Commit cd81a917 authored by Mateusz Guzik's avatar Mateusz Guzik Committed by Paul Moore

mm: introduce get_task_exe_file

For more convenient access if one has a pointer to the task.

As a minor nit take advantage of the fact that only task lock + rcu are
needed to safely grab ->exe_file. This saves mm refcount dance.

Use the helper in proc_exe_link.
Signed-off-by: default avatarMateusz Guzik <mguzik@redhat.com>
Acked-by: default avatarKonstantin Khlebnikov <khlebnikov@yandex-team.ru>
Acked-by: default avatarRichard Guy Briggs <rgb@redhat.com>
Cc: <stable@vger.kernel.org> # 4.3.x
Signed-off-by: default avatarPaul Moore <paul@paul-moore.com>
parent 43761473
......@@ -1552,18 +1552,13 @@ static const struct file_operations proc_pid_set_comm_operations = {
static int proc_exe_link(struct dentry *dentry, struct path *exe_path)
{
struct task_struct *task;
struct mm_struct *mm;
struct file *exe_file;
task = get_proc_task(d_inode(dentry));
if (!task)
return -ENOENT;
mm = get_task_mm(task);
exe_file = get_task_exe_file(task);
put_task_struct(task);
if (!mm)
return -ENOENT;
exe_file = get_mm_exe_file(mm);
mmput(mm);
if (exe_file) {
*exe_path = exe_file->f_path;
path_get(&exe_file->f_path);
......
......@@ -1987,6 +1987,7 @@ extern void mm_drop_all_locks(struct mm_struct *mm);
extern void set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file);
extern struct file *get_mm_exe_file(struct mm_struct *mm);
extern struct file *get_task_exe_file(struct task_struct *task);
extern bool may_expand_vm(struct mm_struct *, vm_flags_t, unsigned long npages);
extern void vm_stat_account(struct mm_struct *, vm_flags_t, long npages);
......
......@@ -773,6 +773,29 @@ struct file *get_mm_exe_file(struct mm_struct *mm)
}
EXPORT_SYMBOL(get_mm_exe_file);
/**
* get_task_exe_file - acquire a reference to the task's executable file
*
* Returns %NULL if task's mm (if any) has no associated executable file or
* this is a kernel thread with borrowed mm (see the comment above get_task_mm).
* User must release file via fput().
*/
struct file *get_task_exe_file(struct task_struct *task)
{
struct file *exe_file = NULL;
struct mm_struct *mm;
task_lock(task);
mm = task->mm;
if (mm) {
if (!(task->flags & PF_KTHREAD))
exe_file = get_mm_exe_file(mm);
}
task_unlock(task);
return exe_file;
}
EXPORT_SYMBOL(get_task_exe_file);
/**
* get_task_mm - acquire a reference to the task's mm
*
......
Markdown is supported
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment