From: Mateusz Jończyk <mat.jonczyk@xxxxx> [ Upstream commit 0dd8d6cb9eddfe637bcd821bbfd40ebd5a0737b9 ] 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 <mat.jonczyk@xxxxx> Cc: Richard Henderson <rth@xxxxxxxxxxx> Cc: Ivan Kokshaysky <ink@xxxxxxxxxxxxxxxxxxxx> Cc: Matt Turner <mattst88@xxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxxxx> Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> Cc: Alessandro Zummo <a.zummo@xxxxxxxxxxxx> Cc: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxx> Cc: linux-alpha@xxxxxxxxxxxxxxx Cc: x86@xxxxxxxxxx Signed-off-by: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxx> Link: https://lore.kernel.org/r/20211210200131.153887-4-mat.jonczyk@xxxxx Stable-dep-of: cd17420ebea5 ("rtc: cmos: avoid UIP when writing alarm time") Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- arch/alpha/kernel/rtc.c | 7 ++++++- arch/x86/kernel/hpet.c | 8 ++++++-- drivers/base/power/trace.c | 6 +++++- drivers/rtc/rtc-cmos.c | 9 ++++++++- drivers/rtc/rtc-mc146818-lib.c | 2 +- 5 files changed, 26 insertions(+), 6 deletions(-) diff --git a/arch/alpha/kernel/rtc.c b/arch/alpha/kernel/rtc.c index 1b1d5963ac55..48ffbfbd0624 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 diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c index 4ab7a9757e52..574df24a8e5a 100644 --- a/arch/x86/kernel/hpet.c +++ b/arch/x86/kernel/hpet.c @@ -1325,8 +1325,12 @@ irqreturn_t hpet_rtc_interrupt(int irq, void *dev_id) hpet_rtc_timer_reinit(); memset(&curr_time, 0, sizeof(struct rtc_time)); - if (hpet_rtc_flags & (RTC_UIE | RTC_AIE)) - mc146818_get_time(&curr_time); + if (hpet_rtc_flags & (RTC_UIE | RTC_AIE)) { + if (unlikely(mc146818_get_time(&curr_time) < 0)) { + pr_err_ratelimited("unable to read current time from RTC\n"); + return IRQ_HANDLED; + } + } if (hpet_rtc_flags & RTC_UIE && curr_time.tm_sec != hpet_prev_update_sec) { diff --git a/drivers/base/power/trace.c b/drivers/base/power/trace.c index 94665037f4a3..72b7a92337b1 100644 --- a/drivers/base/power/trace.c +++ b/drivers/base/power/trace.c @@ -120,7 +120,11 @@ static unsigned int read_magic_time(void) struct rtc_time time; unsigned int val; - mc146818_get_time(&time); + if (mc146818_get_time(&time) < 0) { + pr_err("Unable to read current time from RTC\n"); + return 0; + } + pr_info("RTC time: %ptRt, date: %ptRd\n", &time, &time); val = time.tm_year; /* 100 years */ if (val > 100) diff --git a/drivers/rtc/rtc-cmos.c b/drivers/rtc/rtc-cmos.c index ed4f512eabf0..f8358bb2ae31 100644 --- a/drivers/rtc/rtc-cmos.c +++ b/drivers/rtc/rtc-cmos.c @@ -222,6 +222,8 @@ static inline void cmos_write_bank2(unsigned char val, unsigned char addr) static int cmos_read_time(struct device *dev, struct rtc_time *t) { + int ret; + /* * If pm_trace abused the RTC for storage, set the timespec to 0, * which tells the caller that this RTC value is unusable. @@ -229,7 +231,12 @@ static int cmos_read_time(struct device *dev, struct rtc_time *t) if (!pm_trace_rtc_valid()) return -EIO; - mc146818_get_time(t); + ret = mc146818_get_time(t); + if (ret < 0) { + dev_err_ratelimited(dev, "unable to read current time\n"); + return ret; + } + return 0; } diff --git a/drivers/rtc/rtc-mc146818-lib.c b/drivers/rtc/rtc-mc146818-lib.c index 6262f0680f13..3ae5c690f22b 100644 --- a/drivers/rtc/rtc-mc146818-lib.c +++ b/drivers/rtc/rtc-mc146818-lib.c @@ -24,7 +24,7 @@ unsigned int mc146818_get_time(struct rtc_time *time) /* Ensure that the RTC is accessible. Bit 6 must be 0! */ if (WARN_ON_ONCE((CMOS_READ(RTC_VALID) & 0x40) != 0)) { spin_unlock_irqrestore(&rtc_lock, flags); - memset(time, 0xff, sizeof(*time)); + memset(time, 0, sizeof(*time)); return -EIO; } -- 2.35.1
