Re: [PATCH 5.15.y] clocksource/i8253: Use raw_spinlock_irqsave() in clockevent_i8253_disable()

[Sasha Levin <sashal@kernel.org>]

[ Sasha's backport helper bot ]

Hi,

Summary of potential issues:
⚠️ Found matching upstream commit but patch is missing proper reference to it

Found matching upstream commit: 94cff94634e506a4a44684bee1875d2dbf782722

Status in newer kernel trees:
6.14.y | Present (different SHA1: 6fdc7368341b)
6.12.y | Present (different SHA1: e0e66bb1af60)
6.6.y | Present (different SHA1: 5dd520b92acb)
6.1.y | Present (different SHA1: d2f5f71707cf)

Note: The patch differs from the upstream commit:
---
1:  94cff94634e50 ! 1:  8388aa8badd0d clocksource/i8253: Use raw_spinlock_irqsave() in clockevent_i8253_disable()
    @@ Commit message
         raw_spinlock_irqsave() to cure this.
     
         [ tglx: Massage change log and use guard() ]
    +    [ bigeasy: Dropped guard() for stable ]
     
         Fixes: c8c4076723dac ("x86/timer: Skip PIT initialization on modern chipsets")
         Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
         Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
         Cc: stable@vger.kernel.org
         Link: https://lore.kernel.org/all/20250404133116.p-XRWJXf@linutronix.de
    +    (cherry picked from commit 94cff94634e506a4a44684bee1875d2dbf782722)
    +    Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
     
      ## drivers/clocksource/i8253.c ##
     @@ drivers/clocksource/i8253.c: int __init clocksource_i8253_init(void)
    @@ drivers/clocksource/i8253.c: int __init clocksource_i8253_init(void)
      void clockevent_i8253_disable(void)
      {
     -	raw_spin_lock(&i8253_lock);
    -+	guard(raw_spinlock_irqsave)(&i8253_lock);
    ++	unsigned long flags;
    ++
    ++	raw_spin_lock_irqsave(&i8253_lock, flags);
      
      	/*
      	 * Writing the MODE register should stop the counter, according to
     @@ drivers/clocksource/i8253.c: void clockevent_i8253_disable(void)
    - 	outb_p(0, PIT_CH0);
      
      	outb_p(0x30, PIT_MODE);
    --
    + 
     -	raw_spin_unlock(&i8253_lock);
    ++	raw_spin_unlock_irqrestore(&i8253_lock, flags);
      }
      
      static int pit_shutdown(struct clock_event_device *evt)
---

Results of testing on various branches:

| Branch                    | Patch Apply | Build Test |
|---------------------------|-------------|------------|
| stable/linux-5.15.y       |  Success    |  Success   |