All of lore.kernel.org
 help / color / mirror / Atom feed
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org, Andy Lutomirski <luto@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	x86@kernel.org, "H . Peter Anvin " <hpa@zytor.com>
Subject: Re: [PATCH 1/2] x86/entry: Use should_resched() in idtentry_exit_cond_resched()
Date: Tue, 30 Jun 2020 14:00:59 +0200	[thread overview]
Message-ID: <20200630120059.x5p6uh4hzgqrgwuo@linutronix.de> (raw)
In-Reply-To: <20200630111012.GM4800@hirez.programming.kicks-ass.net>

On 2020-06-30 13:10:12 [+0200], Peter Zijlstra wrote:
> > --- a/arch/x86/entry/common.c
> > +++ b/arch/x86/entry/common.c
> > @@ -612,13 +612,12 @@ bool noinstr idtentry_enter_cond_rcu(struct pt_regs *regs)
> >  
> >  static void idtentry_exit_cond_resched(struct pt_regs *regs, bool may_sched)
> >  {
> > -	if (may_sched && !preempt_count()) {
> > +	if (may_sched && should_resched(0)) {
> >  		/* Sanity check RCU and thread stack */
> >  		rcu_irq_exit_check_preempt();
> >  		if (IS_ENABLED(CONFIG_DEBUG_ENTRY))
> >  			WARN_ON_ONCE(!on_thread_stack());
> 
> This was done on purpose, your change avoids hitting this WARN.
> 
> The thing is, if we could preempt (but not nessecarily have to) we want
> to validate we're on the thread stack.

Okay then.

Sebastian

  reply	other threads:[~2020-06-30 12:01 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-30 10:22 [PATCH 0/2] x86/entry: Tiny idtentry_exit_cond_resched() cleanup Sebastian Andrzej Siewior
2020-06-30 10:22 ` [PATCH 1/2] x86/entry: Use should_resched() in idtentry_exit_cond_resched() Sebastian Andrzej Siewior
2020-06-30 11:10   ` Peter Zijlstra
2020-06-30 12:00     ` Sebastian Andrzej Siewior [this message]
2020-07-01  8:35       ` [PATCH v2] " Sebastian Andrzej Siewior
2020-06-30 10:22 ` [PATCH 2/2] x86/entry: Remove `regs' parameter from idtentry_exit_cond_resched() Sebastian Andrzej Siewior
2020-06-30 11:14   ` Peter Zijlstra
2020-06-30 12:09     ` Sebastian Andrzej Siewior

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200630120059.x5p6uh4hzgqrgwuo@linutronix.de \
    --to=bigeasy@linutronix.de \
    --cc=bp@alien8.de \
    --cc=hpa@zytor.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=luto@kernel.org \
    --cc=mingo@redhat.com \
    --cc=peterz@infradead.org \
    --cc=tglx@linutronix.de \
    --cc=x86@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.