LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Sinan Kaya <okaya@codeaurora.org>
To: linux-parisc@vger.kernel.org, arnd@arndb.de,
	timur@codeaurora.org, sulrich@codeaurora.org
Cc: linux-arm-msm@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	Sinan Kaya <okaya@codeaurora.org>,
	"James E.J. Bottomley" <jejb@parisc-linux.org>,
	Helge Deller <deller@gmx.de>,
	Philippe Ombredanne <pombredanne@nexb.com>,
	Kate Stewart <kstewart@linuxfoundation.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	linux-kernel@vger.kernel.org
Subject: [PATCH v2 2/2] parisc: define stronger ordering for the default readX()
Date: Tue, 17 Apr 2018 00:08:51 -0400	[thread overview]
Message-ID: <1523938133-3224-2-git-send-email-okaya@codeaurora.org> (raw)
In-Reply-To: <1523938133-3224-1-git-send-email-okaya@codeaurora.org>

parisc architecture seems to be mapping readX() and readX_relaxed() APIs
to __raw_readX() API.

__raw_readX() API doesn't provide any kind of ordering guarantees.
commit 032d59e1cde9 ("io: define stronger ordering for the default readX()
implementation") changed asm-generic implementation to use a more
conservative approach towards the readX() API.

Place a barrier() after the register read so that compiler doesn't
optimize across the regiter operation.

Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
---
 arch/parisc/include/asm/io.h | 23 +++++++++++++++++++----
 1 file changed, 19 insertions(+), 4 deletions(-)

diff --git a/arch/parisc/include/asm/io.h b/arch/parisc/include/asm/io.h
index 2ec6405..e04c4ef 100644
--- a/arch/parisc/include/asm/io.h
+++ b/arch/parisc/include/asm/io.h
@@ -179,19 +179,34 @@ static inline void __raw_writeq(unsigned long long b, volatile void __iomem *add
 
 static inline unsigned char readb(const volatile void __iomem *addr)
 {
-	return __raw_readb(addr);
+	unsigned char ret;
+
+	ret = __raw_readb(addr);
+	barrier();
+	return ret;
 }
 static inline unsigned short readw(const volatile void __iomem *addr)
 {
-	return le16_to_cpu((__le16 __force) __raw_readw(addr));
+	unsigned short ret;
+
+	ret = le16_to_cpu((__le16 __force) __raw_readw(addr));
+	barrier();
+	return ret;
 }
 static inline unsigned int readl(const volatile void __iomem *addr)
 {
-	return le32_to_cpu((__le32 __force) __raw_readl(addr));
+	unsigned int ret;
+	ret = le32_to_cpu((__le32 __force) __raw_readl(addr));
+	barrier();
+	return ret;
 }
 static inline unsigned long long readq(const volatile void __iomem *addr)
 {
-	return le64_to_cpu((__le64 __force) __raw_readq(addr));
+	unsigned long long ret;
+
+	ret = le64_to_cpu((__le64 __force) __raw_readq(addr));
+	barrier();
+	return ret;
 }
 
 static inline void writeb(unsigned char b, volatile void __iomem *addr)
-- 
2.7.4

  reply	other threads:[~2018-04-17  4:08 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-17  4:08 [PATCH v2 1/2] parisc: define stronger ordering for the default writeX() Sinan Kaya
2018-04-17  4:08 ` Sinan Kaya [this message]
2018-04-17  9:37   ` [PATCH v2 2/2] parisc: define stronger ordering for the default readX() James Bottomley
2018-04-17 14:13     ` Sinan Kaya
2018-04-17 15:55       ` James Bottomley
2018-04-17 18:28         ` Sinan Kaya
2018-04-17 22:53           ` John David Anglin
2018-04-18 13:39             ` Sinan Kaya

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=1523938133-3224-2-git-send-email-okaya@codeaurora.org \
    --to=okaya@codeaurora.org \
    --cc=arnd@arndb.de \
    --cc=deller@gmx.de \
    --cc=gregkh@linuxfoundation.org \
    --cc=jejb@parisc-linux.org \
    --cc=kstewart@linuxfoundation.org \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-arm-msm@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-parisc@vger.kernel.org \
    --cc=pombredanne@nexb.com \
    --cc=sulrich@codeaurora.org \
    --cc=tglx@linutronix.de \
    --cc=timur@codeaurora.org \
    --subject='Re: [PATCH v2 2/2] parisc: define stronger ordering for the default readX()' \
    /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

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).