[07/13] watchdog: kempld: fix gcc-4.3 build

Message ID	20161216105634.235457-8-arnd@arndb.de
State	Accepted
Commit	3736d4eb6af37492aeded7fec0072dedd959c842
Headers	show Delivered-To: patch@linaro.org Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; From: Arnd Bergmann <arnd@arndb.de> To: linux-arch@vger.kernel.org Cc: linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@vger.kernel.org, Russell King <rmk+kernel@armlinux.org.uk>, Andrew Morton <akpm@linux-foundation.org>, kernel-build-reports@lists.linaro.org, kvmarm@lists.cs.columbia.edu, Arnd Bergmann <arnd@arndb.de> Subject: [PATCH 07/13] watchdog: kempld: fix gcc-4.3 build Date: Fri, 16 Dec 2016 11:56:28 +0100 Message-Id: <20161216105634.235457-8-arnd@arndb.de> In-Reply-To: <20161216105634.235457-1-arnd@arndb.de> References: <20161216105634.235457-1-arnd@arndb.de> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk
Series	[01/13,HACK] gcc-4.5: avoid link errors for unused function pointers \| expand [01/13,HACK] gcc-4.5: avoid link errors for unused function pointers [02/13] KVM: arm: fix gcc-4.5 build [03/13] ARM: div64: fix building with gcc-4.5 and lower [04/13] vfio-pci: use 32-bit comparisons for register address for gcc-4.5 [05/13] clk: pxa: fix gcc-4.4 build [06/13] ARM: atomic: fix gcc-4.4 build [07/13] watchdog: kempld: fix gcc-4.3 build [08/13] arm/arm64: xen: avoid gcc-4.4 warning [09/13] ARM: mark cmpxchg and xchg __always_inline for gcc-4.3 [10/13] asm-generic: mark cmpxchg as __always_inline for gcc-4.3 [11/13] fs: fix unsigned enum warning with gcc-4.2 [12/13] KVM: arm: avoid binary number literals for gcc-4.2 [13/13] ARM: avoid 'Q' asm constraint for gcc-4.1 and earlier

Message ID

20161216105634.235457-8-arnd@arndb.de

State

Accepted

Commit

3736d4eb6af37492aeded7fec0072dedd959c842

Headers

Received-SPF: pass (google.com: best guess record for domain of
	linux-kernel-owner@vger.kernel.org designates 209.132.180.67
	as permitted sender) client-ip=209.132.180.67; 
From: Arnd Bergmann <arnd@arndb.de>
To: linux-arch@vger.kernel.org
Cc: linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-arm-kernel@vger.kernel.org,
	Russell King <rmk+kernel@armlinux.org.uk>,
	Andrew Morton <akpm@linux-foundation.org>,
	kernel-build-reports@lists.linaro.org,
	kvmarm@lists.cs.columbia.edu, Arnd Bergmann <arnd@arndb.de>
Subject: [PATCH 07/13] watchdog: kempld: fix gcc-4.3 build
Date: Fri, 16 Dec 2016 11:56:28 +0100
Message-Id: <20161216105634.235457-8-arnd@arndb.de>
In-Reply-To: <20161216105634.235457-1-arnd@arndb.de>
References: <20161216105634.235457-1-arnd@arndb.de>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Series

[01/13,HACK] gcc-4.5: avoid link errors for unused function pointers | expand

Commit Message

Arnd Bergmann Dec. 16, 2016, 10:56 a.m. UTC

gcc-4.3 can't decide whether the constant value in
kempld_prescaler[PRESCALER_21] is built-time constant or
not, and gets confused by the logic in do_div():

drivers/watchdog/kempld_wdt.o: In function `kempld_wdt_set_stage_timeout':
kempld_wdt.c:(.text.kempld_wdt_set_stage_timeout+0x130): undefined reference to `__aeabi_uldivmod'

This adds a call to ACCESS_ONCE() to force it to not consider
it to be constant, and leaves the more efficient normal case
in place for modern compilers, using an #ifdef to annotate
why we do this hack.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>

---
 drivers/watchdog/kempld_wdt.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

-- 
2.9.0

diff --git a/drivers/watchdog/kempld_wdt.c b/drivers/watchdog/kempld_wdt.c
index 8e302d0e346c..3efa295ac627 100644
--- a/drivers/watchdog/kempld_wdt.c
+++ b/drivers/watchdog/kempld_wdt.c
@@ -140,12 +140,19 @@  static int kempld_wdt_set_stage_timeout(struct kempld_wdt_data *wdt_data,
 					unsigned int timeout)
 {
 	struct kempld_device_data *pld = wdt_data->pld;
-	u32 prescaler = kempld_prescaler[PRESCALER_21];
+	u32 prescaler;
 	u64 stage_timeout64;
 	u32 stage_timeout;
 	u32 remainder;
 	u8 stage_cfg;
 
+#if GCC_VERSION < 40400
+	/* work around a bug compiling do_div() */
+	prescaler = READ_ONCE(kempld_prescaler[PRESCALER_21]);
+#else
+	prescaler = kempld_prescaler[PRESCALER_21];
+#endif
+
 	if (!stage)
 		return -EINVAL;

[07/13] watchdog: kempld: fix gcc-4.3 build

Commit Message

Patch