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a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1522420206; bh=KrL3rspnoXhFNfc6kJLCf/rGowwlDCfFnZzVO6i2oyc=; h=From:To:Cc:Subject:Date:From; b=hspspHNSGj9r9X3Y2IfK7lLH3Z8IId4v2qQ5PB2r6kx7UROD/O7pbRt6ozC0XHCmC YDlnGE+9tTYK5E8gJFthykWGfsWfiU9kNoRmFpQlEoCdxQau04Eb/hS1+rYjqo9b1y oGyLx1g3SbdvhoEslnJHuI+4cb6Llc5tP8B3CiYU= DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 0AF0760ACA Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=okaya@codeaurora.org From: Sinan Kaya To: arnd@arndb.de, timur@codeaurora.org, sulrich@codeaurora.org Subject: [PATCH] io: prevent compiler reordering on the default writeX() implementation Date: Fri, 30 Mar 2018 10:29:58 -0400 Message-Id: <1522420199-23548-1-git-send-email-okaya@codeaurora.org> X-Mailer: git-send-email 2.7.4 MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20180330_103207_487773_A1D88CC3 X-CRM114-Status: GOOD ( 11.45 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Sinan Kaya , linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-arch@vger.kernel.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP The default implementation of mapping writeX() to __raw_writeX() is wrong. writeX() has stronger ordering semantics. Compiler is allowed to reorder __raw_writeX(). In the abscence of a write barrier or when using a strongly ordered architecture, writeX() should at least have a compiler barrier in it to prevent commpiler from clobbering the execution order. Signed-off-by: Sinan Kaya --- include/asm-generic/io.h | 3 +++ 1 file changed, 3 insertions(+) diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h index b4531e3..fbbf2bb 100644 --- a/include/asm-generic/io.h +++ b/include/asm-generic/io.h @@ -153,6 +153,7 @@ static inline void writeb(u8 value, volatile void __iomem *addr) static inline void writew(u16 value, volatile void __iomem *addr) { __raw_writew(cpu_to_le16(value), addr); + barrier(); } #endif @@ -161,6 +162,7 @@ static inline void writew(u16 value, volatile void __iomem *addr) static inline void writel(u32 value, volatile void __iomem *addr) { __raw_writel(__cpu_to_le32(value), addr); + barrier(); } #endif @@ -170,6 +172,7 @@ static inline void writel(u32 value, volatile void __iomem *addr) static inline void writeq(u64 value, volatile void __iomem *addr) { __raw_writeq(__cpu_to_le64(value), addr); + barrier(); } #endif #endif /* CONFIG_64BIT */