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Date: Sun, 20 Feb 2022 10:04:03 +0100 From: Mateusz Jończyk <mat.jonczyk@...pl> To: linux-rtc@...r.kernel.org, linux-kernel@...r.kernel.org Cc: Mateusz Jończyk <mat.jonczyk@...pl>, Alessandro Zummo <a.zummo@...ertech.it>, Alexandre Belloni <alexandre.belloni@...tlin.com>, Thomas Gleixner <tglx@...utronix.de>, stable@...r.kernel.org Subject: [PATCH] rtc-mc146818-lib: fix locking in mc146818_set_time In mc146818_set_time(), CMOS_READ(RTC_CONTROL) was performed without the rtc_lock taken, which is required for CMOS accesses. Fix this. Nothing in kernel modifies RTC_DM_BINARY, so a separate critical section is allowed here. Fixes: dcf257e92622 ("rtc: mc146818: Reduce spinlock section in mc146818_set_time()") Signed-off-by: Mateusz Jończyk <mat.jonczyk@...pl> Cc: Alessandro Zummo <a.zummo@...ertech.it> Cc: Alexandre Belloni <alexandre.belloni@...tlin.com> Cc: Thomas Gleixner <tglx@...utronix.de> Cc: stable@...r.kernel.org --- drivers/rtc/rtc-mc146818-lib.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/rtc/rtc-mc146818-lib.c b/drivers/rtc/rtc-mc146818-lib.c index ae9f131b43c0..562f99b664a2 100644 --- a/drivers/rtc/rtc-mc146818-lib.c +++ b/drivers/rtc/rtc-mc146818-lib.c @@ -232,8 +232,10 @@ int mc146818_set_time(struct rtc_time *time) if (yrs >= 100) yrs -= 100; - if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) - || RTC_ALWAYS_BCD) { + spin_lock_irqsave(&rtc_lock, flags); + save_control = CMOS_READ(RTC_CONTROL); + spin_unlock_irqrestore(&rtc_lock, flags); + if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) { sec = bin2bcd(sec); min = bin2bcd(min); hrs = bin2bcd(hrs); base-commit: 754e0b0e35608ed5206d6a67a791563c631cec07 -- 2.25.1
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