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From: Karl Mehltretter <kmehltretter@gmail.com>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>,
	 Thomas Gleixner <tglx@kernel.org>,
	Clark Williams <clrkwllms@kernel.org>,
	 Steven Rostedt <rostedt@goodmis.org>,
	Boqun Feng <boqun@kernel.org>, Lyude Paul <lyude@redhat.com>,
	 Joel Fernandes <joelagnelf@nvidia.com>,
	Alexander Potapenko <glider@google.com>,
	 linux-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev
Subject: Re: [PATCH] softirq: Preserve interrupt context during IRQ exit
Date: Thu, 3 Sep 2026 17:43:47 +0200	[thread overview]
Message-ID: <apmVB5OtKkYEyskY@gmail.com> (raw)
In-Reply-To: <20260903122017.ZRsTFeks@linutronix.de>

On Thu, Sep 03, 2026 at 02:20:17PM +0100, Sebastian Andrzej Siewior wrote:
> On 2026-09-03 13:27:37 [+0200], Karl Mehltretter wrote:
> > __irq_exit_rcu() drops HARDIRQ_OFFSET before deferred hrtimer rearm,
> > softirq dispatch, and timersd wakeup. This work is still on the IRQ
> > return path, but in_task() reports task context.
> 
> Is this new? I don't remember seeing this before.
> 
> Sebastian

irq_exit() dropped the hardirq count before invoking
softirqs in v2.6.12-rc2, the beginning of git history.

The newer additions to that window are the timersd wakeup added by
49a17639508c and the deferred hrtimer-rearm hook added by
7e641e52cf5f.

Thanks,
Karl

  reply	other threads:[~2026-09-03 15:43 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-09-03 11:27 [PATCH] softirq: Preserve interrupt context during IRQ exit Karl Mehltretter
2026-09-03 12:20 ` Sebastian Andrzej Siewior
2026-09-03 15:43   ` Karl Mehltretter [this message]
2026-09-03 15:22 ` Frederic Weisbecker
2026-09-04 16:45   ` Karl Mehltretter

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