From: Petr Mladek <pmladek@suse.com>
To: Jinjie Ruan <ruanjinjie@huawei.com>
Cc: bcrl@kvack.org, viro@zeniv.linux.org.uk, brauner@kernel.org,
jack@suse.cz, tytso@mit.edu, adilger.kernel@dilger.ca,
libaokun@linux.alibaba.com, ojaswin@linux.ibm.com,
ritesh.list@gmail.com, yi.zhang@huawei.com, sforshee@kernel.org,
akpm@linux-foundation.org, rostedt@goodmis.org,
andriy.shevchenko@linux.intel.com, linux@rasmusvillemoes.dk,
senozhatsky@chromium.org, kees@kernel.org, tglx@kernel.org,
linux-fsdevel@vger.kernel.org, linux-aio@kvack.org,
linux-kernel@vger.kernel.org, linux-ext4@vger.kernel.org
Subject: Re: [PATCH v3 2/8] lib/vsprintf: Use acquire/release for ptr_key publication
Date: Fri, 4 Sep 2026 15:13:27 +0200 [thread overview]
Message-ID: <aprD97HPpbVNW4ir@pathway.suse.cz> (raw)
In-Reply-To: <20260902074805.398540-3-ruanjinjie@huawei.com>
On Wed 2026-09-02 15:47:59, Jinjie Ruan wrote:
> Replace the smp_wmb() + WRITE_ONCE() and READ_ONCE() + smp_rmb() barrier
> pair with smp_store_release()/smp_load_acquire() on filled_random_ptr_key.
>
> This expresses the publish/subscribe pattern more clearly and allows
> architectures with native acquire/release instructions (e.g. arm64's
> STLR/LDAR) to avoid the cost of full one-way barriers (DMB ISHST/ISHLD).
>
> No functional change intended.
>
> Cc: Petr Mladek <pmladek@suse.com>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
> Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Assisted-by: DeepSeek:DeepSeek-V3
> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
Just for record.
The conversion looks correct from the barrier guarantees POV.
I am just not 100% sure about that the performance on different
architectures. I asked this question as a reply on the cover
letter, see https://lore.kernel.org/all/apq5iLOF8lAQ_ZVU@pathway.suse.cz/
Anyway, vsprintf() is not a hot path. So, we do not need to take
care of the performance effect here. Feel free to use:
Reviewed-by: Petr Mladek <pmladek@suse.com>
I am going wait how the discussion about the performance goes.
If it does not block this patchset then I could queue this
particular patch via printk tree.
Best Regards,
Petr
next prev parent reply other threads:[~2026-09-04 13:13 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-02 7:47 [PATCH v3 0/8] Convert barrier pairs to acquire/release for better performance Jinjie Ruan
2026-09-02 7:47 ` [PATCH v3 1/8] user_namespace: Use acquire/release for nr_extents synchronization Jinjie Ruan
2026-09-02 10:09 ` Bradley Morgan
2026-09-02 13:03 ` Andy Shevchenko
2026-09-02 13:04 ` Andy Shevchenko
2026-09-03 1:42 ` Jinjie Ruan
2026-09-03 2:16 ` Jinjie Ruan
2026-09-02 7:47 ` [PATCH v3 2/8] lib/vsprintf: Use acquire/release for ptr_key publication Jinjie Ruan
2026-09-04 13:13 ` Petr Mladek [this message]
2026-09-02 7:48 ` [PATCH v3 3/8] fs: aio: Use acquire/release for ring->tail publication Jinjie Ruan
2026-09-02 7:48 ` [PATCH v3 4/8] fs: Use acquire/release for fdtable resize synchronization Jinjie Ruan
2026-09-02 7:48 ` [PATCH v3 5/8] pidfs: Use test_bit_acquire() for attr flag tests Jinjie Ruan
2026-09-02 7:48 ` [PATCH v3 6/8] super: Use acquire for SB_BORN check in super_cache_count() Jinjie Ruan
2026-09-02 7:48 ` [PATCH v3 7/8] ext4: Fix out-of-bounds read in ext4_get_group_info() Jinjie Ruan
2026-09-02 7:48 ` [PATCH v3 8/8] ext4: Convert group-count barrier protocol to acquire/release Jinjie Ruan
2026-09-02 14:19 ` [PATCH v3 0/8] Convert barrier pairs to acquire/release for better performance Theodore Tso
2026-09-02 14:56 ` Jan Kara
2026-09-04 7:20 ` Jinjie Ruan
2026-09-04 12:28 ` Petr Mladek
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