linux-kernel - [PATCH] proc: less LOCK operations during lookup

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Message-ID: <20071115161325.GF6216@localhost.sw.ru>
Date:	Thu, 15 Nov 2007 19:13:25 +0300
From:	Alexey Dobriyan <adobriyan@...ru>
To:	akpm@...l.org
Cc:	linux-kernel@...r.kernel.org, devel@...nvz.org
Subject: [PATCH] proc: less LOCK operations during lookup

Pseudo-code for lookup effectively is:

	LOCK kernel
	LOCK proc_subdir_lock
		find PDE
		UNLOCK proc_subdir_lock

		get inode

		LOCK proc_subdir_lock
		goto unlock
	UNLOCK proc_subdir_lock
	UNLOCK kernel

We can get rid of LOCK/UNLOCK pair after getting inode simply by jumping
to unlock_kernel() directly.

Signed-off-by: Alexey Dobriyan <adobriyan@...ru>
---

 fs/proc/generic.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/fs/proc/generic.c
+++ b/fs/proc/generic.c
@@ -403,12 +403,12 @@ struct dentry *proc_lookup(struct inode * dir, struct dentry *dentry, struct nam
 				spin_unlock(&proc_subdir_lock);
 				error = -EINVAL;
 				inode = proc_get_inode(dir->i_sb, ino, de);
-				spin_lock(&proc_subdir_lock);
-				break;
+				goto out_unlock;
 			}
 		}
 	}
 	spin_unlock(&proc_subdir_lock);
+out_unlock:
 	unlock_kernel();
 
 	if (inode) {

-
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