linux-kernel - Re: [PATCH] x86/show_trace_log_lvl: ensure stack pointer is aligned, again

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Message-ID: <20230429100826.GA9879@redhat.com>
Date:   Sat, 29 Apr 2023 12:08:27 +0200
From:   Oleg Nesterov <oleg@...hat.com>
To:     Josh Poimboeuf <jpoimboe@...nel.org>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Vernon Lovejoy <vlovejoy@...hat.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86/show_trace_log_lvl: ensure stack pointer is aligned,
 again

On 04/28, Josh Poimboeuf wrote:
>
> On Fri, Apr 28, 2023 at 08:55:13AM +0200, Oleg Nesterov wrote:
> >
> > We decided to make the simplest one-liner fix, but I was thinking about
> >
> > 	for ( stack = stack ?: get_stack_pointer(task, regs);
> > 	     (stack = PTR_ALIGN(stack, sizeof(long)));
> > 	      stack = stack_info.next_sp)
> > 	{
> > 		...
> >
> > to factout out the annoying PTR_ALIGN(). Will it work for you?
>
> I'd rather not, that's a little *too* clever, IMO.

To me

	for (stack = PTR_ALIGN(stack ?: get_stack_pointer(task, regs), sizeof(long));
	     stack;
	     stack = PTR_ALIGN(stack_info.next_sp, sizeof(long)))

certainly looks less readable (and more "clever" ;) but I won't argue with
maintainer. Please see V2.

Oleg.