From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Vincent Mailhol <mailhol.vincent@wanadoo.fr>,
kernel test robot <lkp@intel.com>,
Nathan Chancellor <nathan@kernel.org>,
Marc Kleine-Budde <mkl@pengutronix.de>,
Sasha Levin <sashal@kernel.org>,
wg@grandegger.com, davem@davemloft.net, edumazet@google.com,
kuba@kernel.org, pabeni@redhat.com, ndesaulniers@google.com,
linux-can@vger.kernel.org, netdev@vger.kernel.org,
llvm@lists.linux.dev
Subject: [PATCH AUTOSEL 5.18 144/159] can: mcp251xfd: silence clang's -Wunaligned-access warning
Date: Mon, 30 May 2022 09:24:09 -0400 [thread overview]
Message-ID: <20220530132425.1929512-144-sashal@kernel.org> (raw)
In-Reply-To: <20220530132425.1929512-1-sashal@kernel.org>
From: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
[ Upstream commit 1a6dd9996699889313327be03981716a8337656b ]
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
Link: https://lore.kernel.org/all/20220518114357.55452-1-mailhol.vincent@wanadoo.fr
Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Reported-by: kernel test robot <lkp@intel.com>
Tested-by: Nathan Chancellor <nathan@kernel.org> # build
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 9cb6b5ad8dda..60e56fa4601d 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
parent reply other threads:[~2022-05-30 13:38 UTC|newest]
Thread overview: expand[flat|nested] mbox.gz Atom feed
[parent not found: <20220530132425.1929512-1-sashal@kernel.org>]
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