linux-kernel - [tip:x86/urgent] x86/io: Mark target address as output in 'insb()' asm

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Message-ID: <tip-ea1b2ee6eacc4413b1dfba566480c90d0da4ec81@git.kernel.org>
Date:   Wed, 12 Jul 2017 06:10:19 -0700
From:   tip-bot for Arnd Bergmann <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     peterz@...radead.org, linux-kernel@...r.kernel.org,
        mingo@...nel.org, tglx@...utronix.de, arnd@...db.de,
        brgerst@...il.com, torvalds@...ux-foundation.org,
        kvalo@...eaurora.org, hpa@...or.com, dvlasenk@...hat.com,
        luto@...nel.org, bp@...en8.de, jpoimboe@...hat.com
Subject: [tip:x86/urgent] x86/io: Mark target address as output in 'insb()'
 asm

Commit-ID:  ea1b2ee6eacc4413b1dfba566480c90d0da4ec81
Gitweb:     http://git.kernel.org/tip/ea1b2ee6eacc4413b1dfba566480c90d0da4ec81
Author:     Arnd Bergmann <arnd@...db.de>
AuthorDate: Mon, 10 Jul 2017 16:44:24 +0200
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Wed, 12 Jul 2017 10:42:32 +0200

x86/io: Mark target address as output in 'insb()' asm

The -Wmaybe-uninitialized warning triggers for one driver using the output
of the 'insb' I/O helper on x86:

  drivers/net/wireless/wl3501_cs.c: In function ‘wl3501_mgmt_scan_confirm’:
  drivers/net/wireless/wl3501_cs.c:665:9: error: ‘sig.status’ is used uninitialized in this function [-Werror=uninitialized]
  drivers/net/wireless/wl3501_cs.c:668:12: error: ‘sig.cap_info’ may be used uninitialized in this function [-Werror=maybe-uninitialized]

Apparently the assember constraints are slightly off here, as marking the
'addr' argument as a memory output seems appropriate here and gets rid
of the warning. For consistency I'm also adding it as input for outsb().

Signed-off-by: Arnd Bergmann <arnd@...db.de>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Brian Gerst <brgerst@...il.com>
Cc: Denys Vlasenko <dvlasenk@...hat.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: Kalle Valo <kvalo@...eaurora.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: linux-wireless@...r.kernel.org
Link: http://lkml.kernel.org/r/20170710144425.2238584-1-arnd@arndb.de
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/include/asm/io.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h
index 7afb0e2..d107251 100644
--- a/arch/x86/include/asm/io.h
+++ b/arch/x86/include/asm/io.h
@@ -328,13 +328,13 @@ static inline unsigned type in##bwl##_p(int port)			\
 static inline void outs##bwl(int port, const void *addr, unsigned long count) \
 {									\
 	asm volatile("rep; outs" #bwl					\
-		     : "+S"(addr), "+c"(count) : "d"(port));		\
+		     : "+S"(addr), "+c"(count) : "d"(port), "m" (addr));\
 }									\
 									\
 static inline void ins##bwl(int port, void *addr, unsigned long count)	\
 {									\
 	asm volatile("rep; ins" #bwl					\
-		     : "+D"(addr), "+c"(count) : "d"(port));		\
+		     : "+D"(addr), "+c"(count), "=m" (addr) : "d"(port));\
 }
 
 BUILDIO(b, b, char)