Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit e7a6e291 authored by Alexey Dobriyan's avatar Alexey Dobriyan Committed by Linus Torvalds
Browse files

proc: faster open/close of files without ->release hook 

The whole point of code in fs/proc/inode.c is to make sure ->release
hook is called either at close() or at rmmod time.

All if it is unnecessary if there is no ->release hook.

Save allocation+list manipulations under spinlock in that case.

Link: http://lkml.kernel.org/r/20180214063033.GA15579@avx2


Signed-off-by: default avatarAlexey Dobriyan <adobriyan@gmail.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent e74a0eff

fs/proc/inode.c

+23 −18
Original line number Diff line number Diff line
@@ -342,21 +342,24 @@ static int proc_reg_open(struct inode *inode, struct file *file) 
	 *

	 * Save every "struct file" with custom ->release hook.

	 */

	pdeo = kmalloc(sizeof(struct pde_opener), GFP_KERNEL);

	if (!pdeo)

		return -ENOMEM;



	if (!use_pde(pde)) {

		kfree(pdeo);

	if (!use_pde(pde))

		return -ENOENT;

	}

	open = pde->proc_fops->open;



	release = pde->proc_fops->release;

	if (release) {

		pdeo = kmalloc(sizeof(struct pde_opener), GFP_KERNEL);

		if (!pdeo) {

			rv = -ENOMEM;

			goto out_unuse;

		}

	}



	open = pde->proc_fops->open;

	if (open)

		rv = open(inode, file);



	if (rv == 0 && release) {

	if (release) {

		if (rv == 0) {

			/* To know what to release. */

			pdeo->file = file;

			pdeo->closing = false;
@@ -366,7 +369,9 @@ static int proc_reg_open(struct inode *inode, struct file *file) 
			spin_unlock(&pde->pde_unload_lock);

		} else

			kfree(pdeo);

	}



out_unuse:

	unuse_pde(pde);

	return rv;

}