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

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

fs/proc/base.c

+1 −6
Original line number Diff line number Diff line
@@ -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);

include/linux/mm.h

+1 −0
Original line number Diff line number Diff line
@@ -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);

kernel/fork.c

+23 −0
Original line number Diff line number Diff line
@@ -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

 *

CRA Git | Maintained and supported by SUSTech CRA and CCSE