From: Joe Perches <joe@perches.com>
To: "Paul E. McKenney" <paulmck@kernel.org>, rcu@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, kernel-team@meta.com,
rostedt@goodmis.org, Puranjay Mohan <puranjay@kernel.org>,
Andy Whitcroft <apw@canonical.com>,
Dwaipayan Ray <dwaipayanray1@gmail.com>,
Lukas Bulwahn <lukas.bulwahn@gmail.com>
Subject: Re: [PATCH 3/7] checkpatch: Undeprecate rcu_read_lock_trace() and rcu_read_unlock_trace()
Date: Thu, 07 May 2026 10:44:39 -0700 [thread overview]
Message-ID: <38a4724712f8bda29fae9d9d838dfe27eb1edb7a.camel@perches.com> (raw)
In-Reply-To: <20260507170950.2040199-3-paulmck@kernel.org>
On Thu, 2026-05-07 at 10:09 -0700, Paul E. McKenney wrote:
> It turns out that there are BPF use cases that rely on nesting RCU
> Tasks Trace readers. These use cases are well-served by the old
> rcu_read_lock_trace() and rcu_read_unlock_trace() functions that maintain
> a nesting counter in the task_struct structure. But these use cases incur
> a performance penalty when using the shiny new rcu_read_lock_tasks_trace()
> and rcu_read_unlock_tasks_trace() functions, which nest in the same way
> that SRCU does.
>
> This means that rcu_read_lock_trace() and rcu_read_unlock_trace()
> will be with us for some time. Therefore, remove the checkpatch.pl
> deprecation.
Fine by me.
Perhaps combining patches 3 and 4 would be more intelligible.
next prev parent reply other threads:[~2026-05-07 17:53 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-07 17:09 [PATCH 0/7] Miscellaneous RCU changes for v7.2 Paul E. McKenney
2026-05-07 17:09 ` [PATCH 1/7] srcu: Don't queue workqueue handlers to never-online CPUs Paul E. McKenney
2026-05-07 17:09 ` [PATCH 2/7] srcu: Fix kerneldoc header comment typo in srcu_down_read_fast() Paul E. McKenney
2026-05-07 17:09 ` [PATCH 3/7] checkpatch: Undeprecate rcu_read_lock_trace() and rcu_read_unlock_trace() Paul E. McKenney
2026-05-07 17:44 ` Joe Perches [this message]
2026-05-07 17:53 ` Paul E. McKenney
2026-05-07 17:09 ` [PATCH 4/7] checkpatch: Mark rcu_read_lock_tasks_trace() and friend BPF-only Paul E. McKenney
2026-05-07 17:09 ` [PATCH 5/7] rcu: Simplify rcu_do_batch() by applying clamp() Paul E. McKenney
2026-05-07 17:09 ` [PATCH 6/7] rcu: Simplify param_set_next_fqs_jiffies() by applying clamp_val() Paul E. McKenney
2026-05-07 17:09 ` [PATCH 7/7] rcu: Document rcu_access_pointer() feeding into cmpxchg() Paul E. McKenney
2026-05-08 17:06 ` [PATCH 0/7] Miscellaneous RCU changes for v7.2 Uladzislau Rezki
2026-05-08 17:27 ` Paul E. McKenney
2026-05-08 17:43 ` [PATCH v2 0/6] " Paul E. McKenney
2026-05-08 17:43 ` [PATCH v2 1/6] srcu: Don't queue workqueue handlers to never-online CPUs Paul E. McKenney
2026-05-08 17:43 ` [PATCH v2 2/6] srcu: Fix kerneldoc header comment typo in srcu_down_read_fast() Paul E. McKenney
2026-05-08 17:43 ` [PATCH v2 3/6] checkpatch: Undeprecate rcu_read_lock_trace() and rcu_read_unlock_trace() Paul E. McKenney
2026-05-08 17:43 ` [PATCH v2 4/6] rcu: Simplify rcu_do_batch() by applying clamp() Paul E. McKenney
2026-05-08 17:43 ` [PATCH v2 5/6] rcu: Simplify param_set_next_fqs_jiffies() by applying clamp_val() Paul E. McKenney
2026-05-08 17:43 ` [PATCH v2 6/6] rcu: Document rcu_access_pointer() feeding into cmpxchg() Paul E. McKenney
2026-05-11 9:19 ` [PATCH v2 0/6] Miscellaneous RCU changes for v7.2 Uladzislau Rezki
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