From: Marc Kleine-Budde <mkl@pengutronix.de>
To: netdev@vger.kernel.org
Cc: davem@davemloft.net, kuba@kernel.org, linux-can@vger.kernel.org,
kernel@pengutronix.de,
Vincent Mailhol <mailhol.vincent@wanadoo.fr>,
kernel test robot <lkp@intel.com>,
Nathan Chancellor <nathan@kernel.org>,
Marc Kleine-Budde <mkl@pengutronix.de>
Subject: [PATCH net-next 4/4] can: mcp251xfd: silence clang's -Wunaligned-access warning
Date: Thu, 19 May 2022 22:23:08 +0200 [thread overview]
Message-ID: <20220519202308.1435903-5-mkl@pengutronix.de> (raw)
In-Reply-To: <20220519202308.1435903-1-mkl@pengutronix.de>
From: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
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>
---
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
prev parent reply other threads:[~2022-05-19 20:23 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-19 20:23 [PATCH net-next 0/4] pull-request: can-next 2022-05-19 Marc Kleine-Budde
2022-05-19 20:23 ` [PATCH net-next 1/4] can: isotp: isotp_bind(): do not validate unused address information Marc Kleine-Budde
2022-05-20 0:30 ` patchwork-bot+netdevbpf
2022-05-19 20:23 ` [PATCH net-next 2/4] can: can-dev: move to netif_napi_add_weight() Marc Kleine-Budde
2022-05-19 20:23 ` [PATCH net-next 3/4] can: can-dev: remove obsolete CAN LED support Marc Kleine-Budde
2022-05-19 20:23 ` Marc Kleine-Budde [this message]
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