rtc: Limit RTC PIE frequency

The RTC pie hrtimer is self rearming. We really need to limit the
frequency to something sensible. Thus limit it to the 8192Hz max
value from the rtc man documentation

Cc: Willy Tarreau <w@1wt.eu>
Cc: stable@kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[jstultz: slightly reworked to use RTC_MAX_FREQ value]
Signed-off-by: John Stultz <john.stultz@linaro.org>

diff --git a/drivers/rtc/interface.c b/drivers/rtc/interface.c
index a1ba2caa8308b7cd991130d8b29db2392ba277b5..44e91e598f8d975ae7570b80366a67540611c8da 100644 (file)
--- a/drivers/rtc/interface.c
+++ b/drivers/rtc/interface.c
@@ -708,7 +708,7 @@ int rtc_irq_set_freq(struct rtc_device *rtc, struct rtc_task *task, int freq)
        int err = 0;
        unsigned long flags;
 
-       if (freq <= 0)
+       if (freq <= 0 || freq > RTC_MAX_FREQ)
                return -EINVAL;
 retry:
        spin_lock_irqsave(&rtc->irq_task_lock, flags);

diff --git a/include/linux/rtc.h b/include/linux/rtc.h
index b27ebea25660bff86dbdf2f86040f26904ab45c7..93f4d035076bc8f295fde5b0a6b5b89e4c5df9ff 100644 (file)
--- a/include/linux/rtc.h
+++ b/include/linux/rtc.h
@@ -97,6 +97,9 @@ struct rtc_pll_info {
 #define RTC_AF 0x20    /* Alarm interrupt */
 #define RTC_UF 0x10    /* Update interrupt for 1Hz RTC */
 
+
+#define RTC_MAX_FREQ   8192
+
 #ifdef __KERNEL__
 
 #include <linux/types.h>