From: Peter Zijlstra <peterz@infradead.org>
To: Boqun Feng <boqun.feng@gmail.com>
Cc: linux-kernel@vger.kernel.org, rcu@vger.kernel.org,
lkmm@lists.linux.dev, Ingo Molnar <mingo@kernel.org>,
Will Deacon <will@kernel.org>, Waiman Long <longman@redhat.com>,
Davidlohr Bueso <dave@stgolabs.net>,
"Paul E. McKenney" <paulmck@kernel.org>,
Josh Triplett <josh@joshtriplett.org>,
Frederic Weisbecker <frederic@kernel.org>,
Neeraj Upadhyay <neeraj.upadhyay@kernel.org>,
Joel Fernandes <joelagnelf@nvidia.com>,
Uladzislau Rezki <urezki@gmail.com>,
Steven Rostedt <rostedt@goodmis.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Lai Jiangshan <jiangshanlai@gmail.com>,
Zqiang <qiang.zhang@linux.dev>, Breno Leitao <leitao@debian.org>,
aeh@meta.com, netdev@vger.kernel.org, edumazet@google.com,
jhs@mojatatu.com, kernel-team@meta.com,
Erik Lundgren <elundgren@meta.com>
Subject: Re: [PATCH 4/8] shazptr: Avoid synchronize_shaptr() busy waiting
Date: Wed, 25 Jun 2025 13:40:37 +0200 [thread overview]
Message-ID: <20250625114037.GD1613376@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <20250625031101.12555-5-boqun.feng@gmail.com>
On Tue, Jun 24, 2025 at 08:10:57PM -0700, Boqun Feng wrote:
> +/* Scan structure for synchronize_shazptr(). */
> +struct shazptr_scan {
> + /* The scan kthread */
> + struct task_struct *thread;
> +
> + /* Wait queue for the scan kthread */
> + struct swait_queue_head wq;
> +
> + /* Whether the scan kthread has been scheduled to scan */
> + bool scheduled;
> +
> + /* The lock protecting ->queued and ->scheduled */
> + struct mutex lock;
> +
> + /* List of queued synchronize_shazptr() request. */
> + struct list_head queued;
> +
> + int cpu_grp_size;
> +
> + /* List of scanning synchronize_shazptr() request. */
> + struct list_head scanning;
> +
> + /* Buffer used for hazptr slot scan, nr_cpu_ids slots*/
> + struct shazptr_snapshot* snaps;
> +};
I find this style very hard to read, also the order of things is weird.
struct shazptr_scan {
struct task_struct *thread;
struct swait_queue_head wq;
struct list_head scanning;
struct mutex lock;
struct list_head queued; /* __guarded_by(lock) */
bool scheduled; /* __guarded_by(lock) */
struct shazptr_snapshot snaps[0] __counted_by(nr_cpu_ids);
};
(the __guarded_by() thing will come with Thread-Safety support that
Google is still cooking in clang)
> +static struct shazptr_scan shazptr_scan;
And then make this a pointer, and allocate the whole thing as a single
data structure with however much snaps data you need.
next prev parent reply other threads:[~2025-06-25 11:40 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-06-25 3:10 [PATCH 0/8] Introduce simple hazard pointers for lockdep Boqun Feng
2025-06-25 3:10 ` [PATCH 1/8] Introduce simple hazard pointers Boqun Feng
2025-06-25 10:00 ` Peter Zijlstra
2025-06-25 14:25 ` Mathieu Desnoyers
2025-06-25 15:05 ` Boqun Feng
2025-06-25 15:52 ` Waiman Long
2025-06-25 16:09 ` Boqun Feng
2025-06-25 17:47 ` Waiman Long
2025-06-25 3:10 ` [PATCH 2/8] shazptr: Add refscale test Boqun Feng
2025-06-25 10:02 ` Peter Zijlstra
2025-06-25 3:10 ` [PATCH 3/8] shazptr: Add refscale test for wildcard Boqun Feng
2025-06-25 10:03 ` Peter Zijlstra
2025-06-25 3:10 ` [PATCH 4/8] shazptr: Avoid synchronize_shaptr() busy waiting Boqun Feng
2025-06-25 11:40 ` Peter Zijlstra [this message]
2025-06-25 11:56 ` Peter Zijlstra
2025-06-25 13:56 ` Frederic Weisbecker
2025-06-25 15:24 ` Boqun Feng
2025-06-26 13:45 ` Frederic Weisbecker
2025-06-25 3:10 ` [PATCH 5/8] shazptr: Allow skip self scan in synchronize_shaptr() Boqun Feng
2025-06-25 3:10 ` [PATCH 6/8] rcuscale: Allow rcu_scale_ops::get_gp_seq to be NULL Boqun Feng
2025-06-25 3:11 ` [PATCH 7/8] rcuscale: Add tests for simple hazard pointers Boqun Feng
2025-06-25 3:11 ` [PATCH 8/8] locking/lockdep: Use shazptr to protect the key hashlist Boqun Feng
2025-06-25 11:59 ` Peter Zijlstra
2025-06-25 14:18 ` Boqun Feng
2025-07-10 14:06 ` Breno Leitao
2025-07-11 2:31 ` Boqun Feng
2025-06-25 12:05 ` [PATCH 0/8] Introduce simple hazard pointers for lockdep Christoph Hellwig
2025-06-25 14:08 ` Boqun Feng
2025-06-26 10:16 ` Christoph Hellwig
2025-06-26 13:45 ` Mathieu Desnoyers
2025-06-26 15:47 ` Boqun Feng
2025-06-27 2:56 ` Paul E. McKenney
2025-06-25 12:25 ` Mathieu Desnoyers
2025-06-25 13:21 ` Boqun Feng
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