From 0dd8d6cb9eddfe637bcd821bbfd40ebd5a0737b9 Mon Sep 17 00:00:00 2001 From: Mateusz Jończyk Date: Fri, 10 Dec 2021 21:01:25 +0100 Subject: rtc: Check return value from mc146818_get_time() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit There are 4 users of mc146818_get_time() and none of them was checking the return value from this function. Change this. Print the appropriate warnings in callers of mc146818_get_time() instead of in the function mc146818_get_time() itself, in order not to add strings to rtc-mc146818-lib.c, which is kind of a library. The callers of alpha_rtc_read_time() and cmos_read_time() may use the contents of (struct rtc_time *) even when the functions return a failure code. Therefore, set the contents of (struct rtc_time *) to 0x00, which looks more sensible then 0xff and aligns with the (possibly stale?) comment in cmos_read_time: /* * If pm_trace abused the RTC for storage, set the timespec to 0, * which tells the caller that this RTC value is unusable. */ For consistency, do this in mc146818_get_time(). Note: hpet_rtc_interrupt() may call mc146818_get_time() many times a second. It is very unlikely, though, that the RTC suddenly stops working and mc146818_get_time() would consistently fail. Only compile-tested on alpha. Signed-off-by: Mateusz Jończyk Cc: Richard Henderson Cc: Ivan Kokshaysky Cc: Matt Turner Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: Dave Hansen Cc: Alessandro Zummo Cc: Alexandre Belloni Cc: linux-alpha@vger.kernel.org Cc: x86@kernel.org Signed-off-by: Alexandre Belloni Link: https://lore.kernel.org/r/20211210200131.153887-4-mat.jonczyk@o2.pl --- arch/alpha/kernel/rtc.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'arch/alpha') diff --git a/arch/alpha/kernel/rtc.c b/arch/alpha/kernel/rtc.c index ce3077946e1d..fb3025396ac9 100644 --- a/arch/alpha/kernel/rtc.c +++ b/arch/alpha/kernel/rtc.c @@ -80,7 +80,12 @@ init_rtc_epoch(void) static int alpha_rtc_read_time(struct device *dev, struct rtc_time *tm) { - mc146818_get_time(tm); + int ret = mc146818_get_time(tm); + + if (ret < 0) { + dev_err_ratelimited(dev, "unable to read current time\n"); + return ret; + } /* Adjust for non-default epochs. It's easier to depend on the generic __get_rtc_time and adjust the epoch here than create -- cgit v1.2.3-58-ga151