Patch "watchdog: kempld: fix gcc-4.3 build" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

watchdog: kempld: fix gcc-4.3 build

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
watchdog-kempld-fix-gcc-4.3-build.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Arnd Bergmann <[email protected]>
Date: Wed, 1 Mar 2017 10:15:29 +0100
Subject: watchdog: kempld: fix gcc-4.3 build

From: Arnd Bergmann <[email protected]>

[ Upstream commit 3736d4eb6af37492aeded7fec0072dedd959c842 ]

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.

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

@@ -140,12 +140,19 @@ static int kempld_wdt_set_stage_timeout(
 					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;
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/watchdog-kempld-fix-gcc-4.3-build.patch queue-4.4/percpu-make-this_cpu_generic_read-atomic-w.r.t.-interrupts.patch queue-4.4/cpufreq-cppc-add-acpi_processor-dependency.patch