Re: [PATCH v3 2/8] lib/vsprintf: Use acquire/release for ptr_key publication

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 <redacted>

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/ (local)

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