From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 40CB749CF2D; Thu, 15 Oct 2026 12:48:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=216.40.44.15 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792068510; cv=none; b=XdsspgonB7UuteBB2ckltkZ2Kovhg5AS1MKqHTV/STGxkjzVgT2QeUksYCvgLTEvjBlC7LisrWnZT1Wr3/ln5Hg/3UElaqyB452oY/9Xaf+HnHXlyZjM+lbZbXkIH+KbCTN/hfxeVr25NrJkYFjOyaEuhY7npcy2slcx7BN4QwU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792068510; c=relaxed/simple; bh=Qsbm/VBibiTv9HbUTxARjAoj1Ex1AITSRajHCYKHnck=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=lqmiRKTYqz3ixxMeIBgXcYdZu99YXbSGIY+XrY14tEzIR2zfJldfF1QXY5XiWdrZo0Jf1xp8z00K4rtRNjjTkr8MgWFo5saeLjEj1itSRXSpazszXO1cueN0vHWhyq8khwqAd2/PkLWyOx6uKNcb9Dg7B8GGAaD4uFHfsWkEOMw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=goodmis.org; spf=pass smtp.mailfrom=goodmis.org; dkim=pass (1024-bit key) header.d=goodmis.org header.i=@goodmis.org header.b=QttLPmw2; arc=none smtp.client-ip=216.40.44.15 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=goodmis.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=goodmis.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=goodmis.org header.i=@goodmis.org header.b="QttLPmw2" Received: from omf05.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay09.hostedemail.com (Postfix) with ESMTP id B9744808D8; Thu, 15 Oct 2026 12:48:25 +0000 (UTC) Received: from [HIDDEN] (Authenticated sender: rostedt@goodmis.org) by omf05.hostedemail.com (Postfix) with ESMTPA id 224B920011; Thu, 15 Oct 2026 12:48:22 +0000 (UTC) Date: Thu, 15 Oct 2026 08:48:21 -0400 From: Steven Rostedt To: Karl Mehltretter Cc: Peter Zijlstra , Thomas Gleixner , Sebastian Andrzej Siewior , Frederic Weisbecker , Clark Williams , Boqun Feng , Lyude Paul , Joel Fernandes , Alexander Potapenko , Marco Elver , Jonathan Corbet , Bradley Morgan , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev, Shuah Khan , Randy Dunlap , "Mukesh Kumar Chaurasiya (IBM)" Subject: Re: [PATCH v6] softirq: Preserve interrupt context during IRQ exit Message-ID: <20261015084821.3fcf69bf@gandalf.local.home> In-Reply-To: References: <20261011060742.30584-1-kmehltretter@gmail.com> <20261014120524.5e6e6efe@gandalf.local.home> X-Mailer: Claws Mail 3.20.0git84 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspamout07 X-Rspamd-Queue-Id: 224B920011 X-Stat-Signature: cw6y79efrjsp1e3pwnt8ikui1b5ynufr X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Session-ID: U2FsdGVkX1/HUkKsdimRjPlU0io/+azJMasi0C9lQGg= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=goodmis.org; h=date:from:to:cc:subject:message-id:in-reply-to:references:mime-version:content-type:content-transfer-encoding; s=dkim1; bh=H0/+PoulGnO9Buqg5kAlWZWEdOYZK8eqJ4RSGP7LZxk=; b=QttLPmw2JfHbqt5/kt94/gAp7wKPzPNJAC5+vvxL4Z+79HTpGrhXc8tzQjySQN9IreZVLMGgJSREaVHbpajbZ8tbG3HhC2SEGdE3TOWycBxSL1QZszzkKKxXLFa96qU2Rb5C9fJudH8vBUuQCrrpsGdWa2Dw/Ar22Hme2c8ObRY= X-HE-Tag: 1792068502-981043 X-HE-Meta: U2FsdGVkX19+n9AATYUvQ4XS+ZZAZn9psXV8b1nqX66jlcei0lOsVVnQBjmzskzA78l5gGQpq18AWvg34xTNJ4qiFdRUiQvg8mWyMZ0KVFyM70AQ/0X/6FNQKs2wLSl9cmbPY24aBC0e3O7YICcEq2ZeWY8a2uq1CXa7cQ2CoQ3qZRdMyp9ZOZ//bG8EUBeZSPeXK3YR0b6qJULvT6+DE1rKrHZwzoPjz1pK7NTFZ/YE7dqaLpICqgy8SuqdUPqbRNpzyx0KMSO7a5vcniu7YNFMuON4/0v9T4pikdWGDrbr6UiZ9Bfbb82aI3JpfeN7OIcEtvuJ0J6wzbRgqXPBbGLdzGBjc+qT On Thu, 15 Oct 2026 08:32:12 +0200 Karl Mehltretter wrote: > On Wed, Oct 14, 2026 at 12:05:24PM +0100, Steven Rostedt wrote: > > LGTM. > > > > So this handles the transition between hard irq and softirq? > > > > I wish there was a way to get preempt count updated earlier on entering a > > hard irq so I can get rid of the transition bit in the trace recursion. As > > there's still places that can trigger a trace in the hard irq before > > preempt count is updated. > > > > Yes, this handles the hardirq-to-softirq transition on IRQ exit. > > I am looking into whether the preempt count can be updated before any > traceable code can run, as a potential follow-up RFC. I went down that path before, and the goblins there made me retreat ;-) (I ran out of time to kill all the goblins) > > If that works, it may allow the transition bit to be removed from trace > recursion. I would LOVE that! -- Steve