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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: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Alexey Dobriyan 2018-04-10 16:31:01 -07:00 committed by Linus Torvalds
parent e74a0effff
commit e7a6e291e3
1 changed files with 24 additions and 19 deletions
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43
fs/proc/inode.c
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@ -342,31 +342,36 @@ 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;
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) {
/* To know what to release. */
pdeo->file = file;
pdeo->closing = false;
pdeo->c = NULL;
spin_lock(&pde->pde_unload_lock);
list_add(&pdeo->lh, &pde->pde_openers);
spin_unlock(&pde->pde_unload_lock);
} else
kfree(pdeo);
if (release) {
if (rv == 0) {
/* To know what to release. */
pdeo->file = file;
pdeo->closing = false;
pdeo->c = NULL;
spin_lock(&pde->pde_unload_lock);
list_add(&pdeo->lh, &pde->pde_openers);
spin_unlock(&pde->pde_unload_lock);
} else
kfree(pdeo);
}
out_unuse:
unuse_pde(pde);
return rv;
}