linux-kernel - Re: [PATCH 37/49] x86/alternatives: Move text_poke_array completion from smp_text_poke_batch_finish() and smp_text_poke_batch_flush() to smp_text_poke_batch

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Message-ID: <a64bc000-4226-4d5c-8486-a230f4ff5065@suse.com>
Date: Thu, 3 Apr 2025 16:41:11 +0300
From: Nikolay Borisov <nik.borisov@...e.com>
To: Ingo Molnar <mingo@...nel.org>
Cc: linux-kernel@...r.kernel.org, Juergen Gross <jgross@...e.com>,
 "H . Peter Anvin" <hpa@...or.com>,
 Linus Torvalds <torvalds@...ux-foundation.org>,
 Peter Zijlstra <peterz@...radead.org>, Borislav Petkov <bp@...en8.de>,
 Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 37/49] x86/alternatives: Move text_poke_array completion
 from smp_text_poke_batch_finish() and smp_text_poke_batch_flush() to
 smp_text_poke_batch_process()

On 3.04.25 г. 16:38 ч., Ingo Molnar wrote:
> 
> * Nikolay Borisov <nik.borisov@...e.com> wrote:
> 
>>
>>
>> On 28.03.25 г. 15:26 ч., Ingo Molnar wrote:
>>> Simplifies the code and improves code generation a bit:
>>>
>>>      text	   data	    bss	    dec	    hex	filename
>>>     14769	   1017	   4112	  19898	   4dba	alternative.o.before
>>>     14742	   1017	   4112	  19871	   4d9f	alternative.o.after
>>>
>>> Signed-off-by: Ingo Molnar <mingo@...nel.org>
>>> ---
>>>    arch/x86/kernel/alternative.c | 11 +++++------
>>>    1 file changed, 5 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
>>> index 1df8fac6740d..5293929488f0 100644
>>> --- a/arch/x86/kernel/alternative.c
>>> +++ b/arch/x86/kernel/alternative.c
>>> @@ -2750,6 +2750,9 @@ static void smp_text_poke_batch_process(void)
>>>    		if (unlikely(!atomic_dec_and_test(refs)))
>>>    			atomic_cond_read_acquire(refs, !VAL);
>>>    	}
>>> +
>>> +	/* They are all completed: */
>>> +	text_poke_array.nr_entries = 0;
>>>    }
>>>    static void __smp_text_poke_batch_add(void *addr, const void *opcode, size_t len, const void *emulate)
>>> @@ -2857,20 +2860,16 @@ static bool text_poke_addr_ordered(void *addr)
>>>    void smp_text_poke_batch_finish(void)
>>>    {
>>> -	if (text_poke_array.nr_entries) {
>>> +	if (text_poke_array.nr_entries)
>>>    		smp_text_poke_batch_process();
>>> -		text_poke_array.nr_entries = 0;
>>> -	}
>>>    }
>>
>> This function becomes trivial, why not simply move the check into
>> smp_text_poke_batch_process and rename it to smp_text_poke_batch_finish ?
> 
> Yeah, that's pretty much what happens in patch #47:
> 
>    x86/alternatives: Remove 'smp_text_poke_batch_flush()'

Well, that patch removes poke_batch_flush but still retains 
poke_batch_finish + poke_batch_process. My suggestion is to eliminate 
poke_batch_process name and turn it into poke_batch_finish by moving the 
check from poke_batch_finish into poke_batch_process.

> 
> Thanks,
> 
> 	Ingo