The Linux Kernel Mailing List
 help / color / mirror / Atom feed
From: Arnd Bergmann <arnd@kernel.org>
To: Matt Wu <wuqiang.matt@bytedance.com>
Cc: Arnd Bergmann <arnd@arndb.de>, Yury Norov <yury.norov@gmail.com>,
	linux-kernel@vger.kernel.org
Subject: [PATCH] objpool: fix minimum alignment of 'struct objpool_slot'
Date: Tue, 10 Feb 2026 11:35:24 +0100	[thread overview]
Message-ID: <20260210103530.3028454-1-arnd@kernel.org> (raw)

From: Arnd Bergmann <arnd@arndb.de>

Members of objpool_slot get passed into try_cmpxchg_release(),
which does not work on most architectures unless they are
naturally aligned. Marking the structure as packed makes it
only byte-aligned, as shown by this (normally disabled) warning:

include/linux/objpool.h:156:56: warning: taking address of packed member of 'struct objpool_slot' may result in an unaligned pointer value [-Waddress-of-packed-member]
  156 |                 if (try_cmpxchg_release(&slot->head, &head, head + 1))
      |                                                       ~^~~~~~~~~~~~

As the struct members are all tightly packed on all architectures,
Just remove the '__packed annotation to give it the required
alignment of the native word size.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 include/linux/objpool.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/objpool.h b/include/linux/objpool.h
index b713a1fe7521..f678b35b20b1 100644
--- a/include/linux/objpool.h
+++ b/include/linux/objpool.h
@@ -56,7 +56,7 @@ struct objpool_slot {
 	uint32_t            last;
 	uint32_t            mask;
 	void               *entries[];
-} __packed;
+};
 
 struct objpool_head;
 
-- 
2.39.5


             reply	other threads:[~2026-02-10 10:35 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-02-10 10:35 Arnd Bergmann [this message]
2026-02-11 21:07 ` [PATCH] objpool: fix minimum alignment of 'struct objpool_slot' Yury Norov
2026-02-13  2:15 ` wuqiang.matt
2026-02-13 18:12 ` Yury Norov

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20260210103530.3028454-1-arnd@kernel.org \
    --to=arnd@kernel.org \
    --cc=arnd@arndb.de \
    --cc=linux-kernel@vger.kernel.org \
    --cc=wuqiang.matt@bytedance.com \
    --cc=yury.norov@gmail.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox