From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751354AbeAWAve convert rfc822-to-8bit (ORCPT ); Mon, 22 Jan 2018 19:51:34 -0500 Received: from terminus.zytor.com ([65.50.211.136]:32819 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751253AbeAWAvd (ORCPT ); Mon, 22 Jan 2018 19:51:33 -0500 Date: Mon, 22 Jan 2018 16:46:59 -0800 User-Agent: K-9 Mail for Android In-Reply-To: <1516667578.153063.78.camel@intel.com> References: <20180119143322.16555-1-andriy.shevchenko@linux.intel.com> <1516667578.153063.78.camel@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT Subject: Re: [PATCH v1] x86/io: Define readq()/writeq() to use 64-bit type To: "Mehta, Sohil" , "tglx@linutronix.de" , "andriy.shevchenko@linux.intel.com" , "mingo@redhat.com" , "x86@kernel.org" , "linux-kernel@vger.kernel.org" CC: "mitake@dcl.info.waseda.ac.jp" From: hpa@zytor.com Message-ID: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On January 22, 2018 4:32:14 PM PST, "Mehta, Sohil" wrote: >On Fri, 2018-01-19 at 16:33 +0200, Andy Shevchenko wrote: >> Since non atomic readq() and writeq() were added some of the drivers >> would like to use it in a manner of: >> >>  #include >> ... >>  pr_debug("Debug value of some register: %016llx\n", readq(addr)); >> >> However, lo_hi_readq() always returns __u64 data, while readq() >> on x86_64 defines it as unsigned long. and thus compiler warns >> about type mismatch, although they are both 64-bit on x86_64. >> >> Convert readq() and writeq() on x86 to operate on deterministic >> 64-bit type. The most of architectures in the kernel already are >> using >> either unsigned long long, or u64 type for readq() / writeq(). >> This change propagates consistency in that sense. >> >> While this is not an issue per se, though if someone wants to address >> it, >> the anchor could be the commit >> >>   797a796a13df ("asm-generic: architecture independent readq/writeq >> for 32bit environment") >> >> where non-atomic variants had been introduced. >> >> Note, there are only few users of above pattern and they will not be >> affected because they do cast returned value. The actual warning has >> been issued on not-yet-upstreamed code. >> >> Potentially we might get a new warnings if some 64-bit only code >> assigns returned value to unsigned long type of variable. This is >> assumed to be addressed on case-by-case basis. >> >> Reported-by: lkp >> Cc: Hitoshi Mitake >> Cc: "Mehta, Sohil" >> Signed-off-by: Andy Shevchenko >> --- >>  arch/x86/include/asm/io.h | 8 ++++---- >>  1 file changed, 4 insertions(+), 4 deletions(-) >> >> diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h >> index 95e948627fd0..365f5ba9222b 100644 >> --- a/arch/x86/include/asm/io.h >> +++ b/arch/x86/include/asm/io.h >> @@ -94,10 +94,10 @@ build_mmio_write(__writel, "l", unsigned int, >> "r", ) >>   >>  #ifdef CONFIG_X86_64 >>   >> -build_mmio_read(readq, "q", unsigned long, "=r", :"memory") >> -build_mmio_read(__readq, "q", unsigned long, "=r", ) >> -build_mmio_write(writeq, "q", unsigned long, "r", :"memory") >> -build_mmio_write(__writeq, "q", unsigned long, "r", ) >> +build_mmio_read(readq, "q", unsigned long long, "=r", :"memory") >> +build_mmio_read(__readq, "q", unsigned long long, "=r", ) >> +build_mmio_write(writeq, "q", unsigned long long, "r", :"memory") >> +build_mmio_write(__writeq, "q", unsigned long long, "r", ) >>   >>  #define readq_relaxed(a) __readq(a) >>  #define writeq_relaxed(v, a) __writeq(v, a) > >The patch works for me: > >Tested-by: Sohil Mehta > >Sohil Wouldn't simply u64 make more sense? -- Sent from my Android device with K-9 Mail. Please excuse my brevity.