All of lore.kernel.org
 help / color / mirror / Atom feed
From: Chen Gang <chengang@emindsoft.com.cn>
To: arnd@arndb.de, Andrew Morton <akpm@linux-foundation.org>
Cc: Linux-Arch <linux-arch@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Chen Gang <gang.chen.5i5j@gmail.com>,
	chenwei@emindsoft.com.cn
Subject: [PATCH] include/asm-generic/pgtable.h: Check once and return for pgprot_modify
Date: Sun, 13 Dec 2015 17:12:02 +0800	[thread overview]
Message-ID: <566D3662.6080804@emindsoft.com.cn> (raw)


pgprot_val() likes an empty operation, and all three checking statements
are related with oldprot, so only check once is enough, the reason is:

 - if both "oldprot == pgprot_noncached(oldprot)" and "oldprot ==
   pgprot_writecombine(oldprot)" are satisfied.

 - So "pgprot_noncached(oldprot) == pgprot_writecombine(oldprot)", too.

 - So as the result, it is still equal to check once (for pgprot_device
   can get the same result).

Then can return directly.

Signed-off-by: Chen Gang <gang.chen.5i5j@gmail.com>
---
 include/asm-generic/pgtable.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
index 069536a..cd9e7c4 100644
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -306,11 +306,11 @@ static inline int pmd_same(pmd_t pmd_a, pmd_t pmd_b)
 static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
 {
 	if (pgprot_val(oldprot) == pgprot_val(pgprot_noncached(oldprot)))
-		newprot = pgprot_noncached(newprot);
+		return pgprot_noncached(newprot);
 	if (pgprot_val(oldprot) == pgprot_val(pgprot_writecombine(oldprot)))
-		newprot = pgprot_writecombine(newprot);
+		return pgprot_writecombine(newprot);
 	if (pgprot_val(oldprot) == pgprot_val(pgprot_device(oldprot)))
-		newprot = pgprot_device(newprot);
+		return pgprot_device(newprot);
 	return newprot;
 }
 #endif
-- 
1.9.3

             reply	other threads:[~2015-12-13  9:12 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-12-13  9:12 Chen Gang [this message]
2015-12-13 15:46 ` [PATCH] include/asm-generic/pgtable.h: Check once and return for pgprot_modify Chen Gang

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=566D3662.6080804@emindsoft.com.cn \
    --to=chengang@emindsoft.com.cn \
    --cc=akpm@linux-foundation.org \
    --cc=arnd@arndb.de \
    --cc=chenwei@emindsoft.com.cn \
    --cc=gang.chen.5i5j@gmail.com \
    --cc=linux-arch@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.