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From: Peter Zijlstra <peterz@infradead.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Frederic Weisbecker <frederic@kernel.org>,
	Paul McKenney <paulmck@kernel.org>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Subject: Re: [patch V2 4/9] softirq: Make softirq control and processing RT aware
Date: Wed, 9 Dec 2020 11:34:27 +0100	[thread overview]
Message-ID: <20201209103427.GK2414@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20201204170805.114951971@linutronix.de>

On Fri, Dec 04, 2020 at 06:01:55PM +0100, Thomas Gleixner wrote:
> +void __local_bh_disable_ip(unsigned long ip, unsigned int cnt)
> +{
> +	unsigned long flags;
> +	int newcnt;
> +
> +	WARN_ON_ONCE(in_hardirq());
> +
> +	/* First entry of a task into a BH disabled section? */
> +	if (!current->softirq_disable_cnt) {
> +		if (preemptible()) {

This reminds me of that migrate_disable() thing that didn't work, and
has similar problems.

	preempt_disable();
	local_bh_disable();
	preempt_enable();
	spin_lock(&foo);

is valid (albeit daft) code that will now malfunction.

> +			local_lock(&softirq_ctrl.lock);



  parent reply	other threads:[~2020-12-09 10:35 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-04 17:01 [patch V2 0/9] softirq: Make it RT aware Thomas Gleixner
2020-12-04 17:01 ` [patch V2 1/9] softirq: Add RT specific softirq accounting Thomas Gleixner
2020-12-07 13:06   ` Frederic Weisbecker
2020-12-04 17:01 ` [patch V2 2/9] irqtime: Make accounting correct on RT Thomas Gleixner
2020-12-07  0:23   ` Frederic Weisbecker
2020-12-07  0:57     ` Thomas Gleixner
2020-12-07  1:14       ` Frederic Weisbecker
2020-12-07 13:27   ` Frederic Weisbecker
2020-12-07 14:44     ` Thomas Gleixner
2020-12-04 17:01 ` [patch V2 3/9] softirq: Move various protections into inline helpers Thomas Gleixner
2020-12-07 13:37   ` Frederic Weisbecker
2020-12-04 17:01 ` [patch V2 4/9] softirq: Make softirq control and processing RT aware Thomas Gleixner
2020-12-07 14:16   ` Frederic Weisbecker
2020-12-07 15:08     ` Thomas Gleixner
2020-12-08  0:08   ` Frederic Weisbecker
2020-12-09 10:11   ` Peter Zijlstra
2020-12-09 12:36     ` Thomas Gleixner
2020-12-09 12:42       ` Peter Zijlstra
2020-12-09 13:30         ` Thomas Gleixner
2020-12-09 10:34   ` Peter Zijlstra [this message]
2020-12-04 17:01 ` [patch V2 5/9] tick/sched: Prevent false positive softirq pending warnings on RT Thomas Gleixner
2020-12-08 12:23   ` Frederic Weisbecker
2020-12-04 17:01 ` [patch V2 6/9] rcu: Prevent false positive softirq warning " Thomas Gleixner
2020-12-04 17:59   ` Paul E. McKenney
2020-12-04 17:01 ` [patch V2 7/9] softirq: Replace barrier() with cpu_relax() in tasklet_unlock_wait() Thomas Gleixner
2020-12-07 11:39   ` Peter Zijlstra
2020-12-07 15:21     ` Thomas Gleixner
2020-12-04 17:01 ` [patch V2 8/9] tasklets: Use static inlines for stub implementations Thomas Gleixner
2020-12-04 17:02 ` [patch V2 9/9] tasklets: Prevent kill/unlock_wait deadlock on RT Thomas Gleixner
2020-12-07 11:47   ` Peter Zijlstra
2020-12-07 14:00     ` Sebastian Andrzej Siewior
2020-12-07 14:27       ` Peter Zijlstra
2020-12-07 17:55         ` Thomas Gleixner
2020-12-07 15:22       ` Thomas Gleixner
2020-12-07 15:39         ` Sebastian Andrzej Siewior
2020-12-07 17:49           ` Thomas Gleixner
2020-12-07 17:50             ` Thomas Gleixner
2020-12-06 10:05 ` [patch V2 0/9] softirq: Make it RT aware Sebastian Andrzej Siewior

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