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From: Frederic Weisbecker <frederic@kernel.org>
To: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Josef Bacik <josef@toxicpanda.com>,
	Neeraj Upadhyay <neeraj.upadhyay@kernel.org>,
	Joel Fernandes <joelagnelf@nvidia.com>,
	Boqun Feng <boqun@kernel.org>, Thomas Gleixner <tglx@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>, Jiri Olsa <jolsa@kernel.org>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>,
	x86@kernel.org, Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	Puranjay Mohan <puranjay@kernel.org>,
	Xu Kuohai <xukuohai@huaweicloud.com>,
	Andy Lutomirski <luto@kernel.org>,
	Josh Triplett <josh@joshtriplett.org>,
	Uladzislau Rezki <urezki@gmail.com>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Lai Jiangshan <jiangshanlai@gmail.com>,
	Zqiang <qiang.zhang@linux.dev>, Juergen Gross <jgross@suse.com>,
	Luis Chamberlain <mcgrof@kernel.org>,
	Ihor Solodrai <ihor.solodrai@linux.dev>,
	linux-kernel@vger.kernel.org, rcu@vger.kernel.org,
	linux-trace-kernel@vger.kernel.org, bpf@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	xen-devel@lists.xenproject.org
Subject: Re: [PATCH RFC v3 03/13] rcu-tasks: Add a Tasks RCU implementation for reader-marked trampolines
Date: Thu, 17 Sep 2026 20:45:36 +0200	[thread overview]
Message-ID: <aqw1UNGO3cQxvCco@pavilion.home> (raw)
In-Reply-To: <8fea176a-0ca0-4a70-8cf9-8240a22359e4@paulmck-laptop>

Le Thu, Sep 17, 2026 at 08:40:10AM -0700, Paul E. McKenney a écrit :
> > > Trampolines that transfer control to tracing code could supply the needed
> > > cleanup call.  But last I checked, there were trampolines that transferred
> > > directly back to the original code, with no opportunity for cleaning up.
> > > 
> > > Or am I still missing a trick here?
> > 
> > You're right. So we'll indeed need to reuse the deferred qs points here.
> 
> Except this is getting a bit involved.
> 
> Don't get me wrong, if Josef is happy to take this on, far be it from me
> to stand in his way.  But if not, we should be willing to treat this
> optimization as a follow-on effort, whether by Josef or someone else.

Sure, I guess I can try the follow-on, especially if it leads to removing
all this RCU tasks black magic.

Thanks.

-- 
Frederic Weisbecker
SUSE Labs


  parent reply	other threads:[~2026-09-17 19:34 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-09-15 13:17 [PATCH RFC v3 00/13] rcu-tasks: build Tasks RCU on Tasks Trace readers in trampolines Josef Bacik
2026-09-15 13:17 ` [PATCH RFC v3 01/13] entry: Pass pt_regs to irqentry_exit_cond_resched() Josef Bacik
2026-09-15 14:17   ` bot+bpf-ci
2026-09-15 13:17 ` [PATCH RFC v3 02/13] rcu-tasks-trace: Inline rcu_read_lock_trace() and annotate inside the reader Josef Bacik
2026-09-15 14:17   ` bot+bpf-ci
2026-09-15 13:17 ` [PATCH RFC v3 03/13] rcu-tasks: Add a Tasks RCU implementation for reader-marked trampolines Josef Bacik
2026-09-15 13:29   ` sashiko-bot
2026-09-15 16:02     ` Josef Bacik
2026-09-15 15:14   ` Frederic Weisbecker
2026-09-15 23:56     ` Paul E. McKenney
2026-09-16 12:40       ` Frederic Weisbecker
2026-09-16 14:26         ` Paul E. McKenney
2026-09-16 14:35           ` Frederic Weisbecker
2026-09-16 14:47             ` Frederic Weisbecker
2026-09-16 14:55               ` Paul E. McKenney
2026-09-16 15:23                 ` Frederic Weisbecker
2026-09-16 15:41                   ` Paul E. McKenney
2026-09-17 12:14                     ` Frederic Weisbecker
2026-09-17 15:40                       ` Paul E. McKenney
2026-09-17 16:35                         ` Josef Bacik
2026-09-17 16:55                           ` Paul E. McKenney
2026-09-17 18:45                         ` Frederic Weisbecker [this message]
2026-09-17 19:25                           ` Paul E. McKenney
2026-09-17 20:31                             ` Paul E. McKenney
2026-09-17 20:20   ` Frederic Weisbecker
2026-09-22 15:42     ` Josef Bacik
2026-09-15 13:17 ` [PATCH RFC v3 04/13] kprobes: Expose the optprobe jump window to Tasks RCU Josef Bacik
2026-09-15 13:17 ` [PATCH RFC v3 05/13] ftrace: Mark modules hosting direct-call trampolines for " Josef Bacik
2026-09-15 14:17   ` bot+bpf-ci
2026-09-15 16:03     ` Josef Bacik
2026-09-15 13:17 ` [PATCH RFC v3 06/13] bpf: Take a Tasks Trace reader in the trampoline glue Josef Bacik
2026-09-16  3:45   ` Alexei Starovoitov
2026-09-17  1:16     ` Josef Bacik
2026-09-17  2:24       ` Alexei Starovoitov
2026-09-15 13:17 ` [PATCH RFC v3 07/13] x86/ftrace: Take a Tasks Trace reader around ftrace_caller's call-out Josef Bacik
2026-09-15 13:17 ` [PATCH RFC v3 08/13] x86/kprobes: Take a Tasks Trace reader in the optprobe template Josef Bacik
2026-09-15 13:17 ` [PATCH RFC v3 09/13] arm64: ftrace: Take a Tasks Trace reader around ftrace_caller's call-out Josef Bacik
2026-09-15 13:17 ` [PATCH RFC v3 10/13] samples: ftrace: Make the direct-call trampolines Tasks Trace readers Josef Bacik
2026-09-15 13:17 ` [PATCH RFC v3 11/13] rcutorture: Make Tasks RCU readers Tasks Trace readers where required Josef Bacik
2026-09-15 13:17 ` [PATCH RFC v3 12/13] rcu-tasks-trace: Assert no reader is held on return to userspace Josef Bacik
2026-09-15 13:17 ` [PATCH RFC v3 13/13] x86, arm64: Build Tasks RCU on Tasks Trace readers in trampolines Josef Bacik
2026-09-15 14:17   ` bot+bpf-ci

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