From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pg1-f182.google.com (mail-pg1-f182.google.com [209.85.215.182]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 584E546BB for ; Wed, 18 May 2022 11:44:52 +0000 (UTC) Received: by mail-pg1-f182.google.com with SMTP id r71so1946649pgr.0 for ; Wed, 18 May 2022 04:44:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=sender:from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=e46I4qIXdzquI9xFD+cV1ACVVNgw+INdEKQ9QEnr4OI=; b=Nh0/Gtjh+a2IoDWF2IsH6LjJsbfFa2ls+RGo/YWXGFgUkeucd2niQ5WCVQPYpf7y/U Cmx7pTzDQ9PP7tNRsnHmU/9qAi3OmK/wmyx0mwTd43+fQjvAPKpQvyRobrqOUIpfYS0F BG2A7C0p12X4zCfzNvUX5A+eLouTQSkWu6dcUMwnQ2ue1CqLrYL2cG3libYJjprTw7Y1 YW1N3/mdmXaPY+HtNABFX05KqegIBIotIqJyW45Y/6gv7g3Oi/bfNhZpark+UsHId/tA A5xAUzQaT2R2SzuL34L0HlW73CMoooDFXUTKbqr8g4DPAY7oQY8GzPPfXhe2JfYajuaH fytg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:sender:from:to:cc:subject:date:message-id :in-reply-to:references:mime-version:content-transfer-encoding; bh=e46I4qIXdzquI9xFD+cV1ACVVNgw+INdEKQ9QEnr4OI=; b=xOBAyX1QVHt894/mboJxyZPWl4XdHqKYF7kzSg1SHnY8/XR9GhZM5mU3r9riYtiEXu 8wmOUVgM4GMOXilVolcwyE190Hp1ICO/Hhtz9IE8QyR9oIqYN4dBf/CNTRAhwN4DfsOa jKbvKS+XkK21NFKpDgHiB8yLljKdJC3xOnTxuyfMi9FpbVYU/6vxXLLok+YI2Jrt4iqJ TmqxIJyMQkgXxKhllIISKkpN4Kiu29vwEVl2w8vjZ24JhmiBdfmrr1Fokp8+orL35XjG hOTHd9apEZDBhuqHxpXEBVJpAHvg/pO8QGU0mEN5oxli12maofL4Nv/ZeDulOO+pB8XO Xkkg== X-Gm-Message-State: AOAM533l9yVCd7phe84RC8EROKWaONOG4g6uB3OZFd4nXBdXsE+5hZC1 gzHKBpN1a3FJb3RiZjQJs0A= X-Google-Smtp-Source: ABdhPJzYBLHwICpNdU1uIc/fY0ueEsP71iwvxE76n7L9d8J1eiIBw//HBvohkbNgfUiutXbkZMTFNA== X-Received: by 2002:a05:6a00:14cf:b0:510:5549:ad8a with SMTP id w15-20020a056a0014cf00b005105549ad8amr27233402pfu.24.1652874291646; Wed, 18 May 2022 04:44:51 -0700 (PDT) Received: from localhost.localdomain (124x33x176x97.ap124.ftth.ucom.ne.jp. [124.33.176.97]) by smtp.gmail.com with ESMTPSA id 23-20020a631557000000b003db8691008esm1332158pgv.12.2022.05.18.04.44.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 18 May 2022 04:44:51 -0700 (PDT) Sender: Vincent Mailhol From: Vincent Mailhol To: Marc Kleine-Budde , kernel test robot Cc: llvm@lists.linux.dev, kbuild-all@lists.01.org, linux-kernel@vger.kernel.org, linux-can@vger.kernel.org, Vincent Mailhol Subject: [PATCH] can: mcp251xfd: silence clang's -Wunaligned-access warning Date: Wed, 18 May 2022 20:43:57 +0900 Message-Id: <20220518114357.55452-1-mailhol.vincent@wanadoo.fr> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220518070517.q53bjzo6lbnq3f2i@pengutronix.de> References: <20220518070517.q53bjzo6lbnq3f2i@pengutronix.de> Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit clang emits a -Wunaligned-access warning on union mcp251xfd_tx_ojb_load_buf. The reason is that field hw_tx_obj (not declared as packed) is being packed right after a 16 bits field inside a packed struct: | union mcp251xfd_tx_obj_load_buf { | struct __packed { | struct mcp251xfd_buf_cmd cmd; | /* ^ 16 bits fields */ | struct mcp251xfd_hw_tx_obj_raw hw_tx_obj; | /* ^ not declared as packed */ | } nocrc; | struct __packed { | struct mcp251xfd_buf_cmd_crc cmd; | struct mcp251xfd_hw_tx_obj_raw hw_tx_obj; | __be16 crc; | } crc; | } ____cacheline_aligned; Starting from LLVM 14, having an unpacked struct nested in a packed struct triggers a warning. c.f. [1]. This is a false positive because the field is always being accessed with the relevant put_unaligned_*() function. Adding __packed to the structure declaration silences the warning. [1] https://github.com/llvm/llvm-project/issues/55520 Signed-off-by: Vincent Mailhol --- Actually, I do not have llvm 14 installed so I am not able to test (this check was introduced in v14). But as explained in [1], adding __packed should fix the warning. Because this is a false positive, I did not add a Fixes tag, nor a Reported-by: kernel test robot. --- drivers/net/can/spi/mcp251xfd/mcp251xfd.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/can/spi/mcp251xfd/mcp251xfd.h b/drivers/net/can/spi/mcp251xfd/mcp251xfd.h index 1d43bccc29bf..2b0309fedfac 100644 --- a/drivers/net/can/spi/mcp251xfd/mcp251xfd.h +++ b/drivers/net/can/spi/mcp251xfd/mcp251xfd.h @@ -441,7 +441,7 @@ struct mcp251xfd_hw_tef_obj { /* The tx_obj_raw version is used in spi async, i.e. without * regmap. We have to take care of endianness ourselves. */ -struct mcp251xfd_hw_tx_obj_raw { +struct __packed mcp251xfd_hw_tx_obj_raw { __le32 id; __le32 flags; u8 data[sizeof_field(struct canfd_frame, data)]; -- 2.35.1 From mboxrd@z Thu Jan 1 00:00:00 1970 Content-Type: multipart/mixed; boundary="===============7333886379467794685==" MIME-Version: 1.0 From: Vincent Mailhol To: kbuild-all@lists.01.org Subject: [PATCH] can: mcp251xfd: silence clang's -Wunaligned-access warning Date: Wed, 18 May 2022 20:43:57 +0900 Message-ID: <20220518114357.55452-1-mailhol.vincent@wanadoo.fr> In-Reply-To: <20220518070517.q53bjzo6lbnq3f2i@pengutronix.de> List-Id: --===============7333886379467794685== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable clang emits a -Wunaligned-access warning on union mcp251xfd_tx_ojb_load_buf. The reason is that field hw_tx_obj (not declared as packed) is being packed right after a 16 bits field inside a packed struct: | union mcp251xfd_tx_obj_load_buf { | struct __packed { | struct mcp251xfd_buf_cmd cmd; | /* ^ 16 bits fields */ | struct mcp251xfd_hw_tx_obj_raw hw_tx_obj; | /* ^ not declared as packed */ | } nocrc; | struct __packed { | struct mcp251xfd_buf_cmd_crc cmd; | struct mcp251xfd_hw_tx_obj_raw hw_tx_obj; | __be16 crc; | } crc; | } ____cacheline_aligned; Starting from LLVM 14, having an unpacked struct nested in a packed struct triggers a warning. c.f. [1]. This is a false positive because the field is always being accessed with the relevant put_unaligned_*() function. Adding __packed to the structure declaration silences the warning. [1] https://github.com/llvm/llvm-project/issues/55520 Signed-off-by: Vincent Mailhol --- Actually, I do not have llvm 14 installed so I am not able to test (this check was introduced in v14). But as explained in [1], adding __packed should fix the warning. Because this is a false positive, I did not add a Fixes tag, nor a Reported-by: kernel test robot. --- drivers/net/can/spi/mcp251xfd/mcp251xfd.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/can/spi/mcp251xfd/mcp251xfd.h b/drivers/net/can/sp= i/mcp251xfd/mcp251xfd.h index 1d43bccc29bf..2b0309fedfac 100644 --- a/drivers/net/can/spi/mcp251xfd/mcp251xfd.h +++ b/drivers/net/can/spi/mcp251xfd/mcp251xfd.h @@ -441,7 +441,7 @@ struct mcp251xfd_hw_tef_obj { /* The tx_obj_raw version is used in spi async, i.e. without * regmap. We have to take care of endianness ourselves. */ -struct mcp251xfd_hw_tx_obj_raw { +struct __packed mcp251xfd_hw_tx_obj_raw { __le32 id; __le32 flags; u8 data[sizeof_field(struct canfd_frame, data)]; -- = 2.35.1 --===============7333886379467794685==--