linux-kernel - [PATCH] proc: skip branch in /proc/*/* lookup

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Message-ID: <20180423213954.GD9043@avx2>
Date:   Tue, 24 Apr 2018 00:39:54 +0300
From:   Alexey Dobriyan <adobriyan@...il.com>
To:     akpm@...ux-foundation.org
Cc:     linux-kernel@...r.kernel.org
Subject: [PATCH] proc: skip branch in /proc/*/* lookup

Code is structured like this:

	for ( ... p < last; p++) {
		if (memcmp == 0)
			break;
	}
	if (p >= last)
		ERROR
	OK

gcc doesn't see that if if lookup succeeds than post loop branch will
never be taken and skip it.

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

 fs/proc/base.c |    9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2485,14 +2485,11 @@ static struct dentry *proc_pident_lookup(struct inode *dir,
 	for (p = ents; p < last; p++) {
 		if (p->len != dentry->d_name.len)
 			continue;
-		if (!memcmp(dentry->d_name.name, p->name, p->len))
+		if (!memcmp(dentry->d_name.name, p->name, p->len)) {
+			error = proc_pident_instantiate(dir, dentry, task, p);
 			break;
+		}
 	}
-	if (p >= last)
-		goto out;
-
-	error = proc_pident_instantiate(dir, dentry, task, p);
-out:
 	put_task_struct(task);
 out_no_task:
 	return ERR_PTR(error);