net/smc/smc_llc.c:40:1: warning: alignment 1 of 'struct smc_llc_hdr' is less than 4

From: kernel test robot
Date: Sat Jul 30 2022 - 19:01:58 EST


Hi Karsten,

FYI, the error/warning still remains.

tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head: 620725263f4222b3c94d4ee19846835feec0ad69
commit: b4ba4652b3f8b7c9bbb5786f8acf4724bdab2196 net/smc: extend LLC layer for SMC-Rv2
date: 10 months ago
config: arm-randconfig-r036-20220731 (https://download.01.org/0day-ci/archive/20220731/202207310658.ERb14Td9-lkp@xxxxxxxxx/config)
compiler: arm-linux-gnueabi-gcc (GCC) 12.1.0
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b4ba4652b3f8b7c9bbb5786f8acf4724bdab2196
git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
git fetch --no-tags linus master
git checkout b4ba4652b3f8b7c9bbb5786f8acf4724bdab2196
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=arm SHELL=/bin/bash net/smc/

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@xxxxxxxxx>

All warnings (new ones prefixed by >>):

In file included from include/linux/gfp.h:6,
from include/linux/xarray.h:14,
from include/linux/radix-tree.h:19,
from include/linux/fs.h:15,
from include/linux/highmem.h:5,
from include/linux/bvec.h:10,
from include/linux/skbuff.h:17,
from include/linux/tcp.h:17,
from include/net/tcp.h:20,
from net/smc/smc_llc.c:13:
include/linux/mmzone.h: In function '__nr_to_section':
include/linux/mmzone.h:1349:13: warning: the comparison will always evaluate as 'true' for the address of 'mem_section' will never be NULL [-Waddress]
1349 | if (!mem_section[SECTION_NR_TO_ROOT(nr)])
| ^
include/linux/mmzone.h:1335:27: note: 'mem_section' declared here
1335 | extern struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT];
| ^~~~~~~~~~~
net/smc/smc_llc.c: At top level:
>> net/smc/smc_llc.c:40:1: warning: alignment 1 of 'struct smc_llc_hdr' is less than 4 [-Wpacked-not-aligned]
40 | } __packed; /* format defined in
| ^
In file included from <command-line>:
net/smc/smc_llc.c: In function 'smc_llc_add_pending_send':
include/linux/compiler_types.h:322:45: error: call to '__compiletime_assert_564' declared with attribute error: must increase SMC_WR_BUF_SIZE to at least sizeof(struct smc_llc_msg)
322 | _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
| ^
include/linux/compiler_types.h:303:25: note: in definition of macro '__compiletime_assert'
303 | prefix ## suffix(); \
| ^~~~~~
include/linux/compiler_types.h:322:9: note: in expansion of macro '_compiletime_assert'
322 | _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
| ^~~~~~~~~~~~~~~~~~~
include/linux/build_bug.h:39:37: note: in expansion of macro 'compiletime_assert'
39 | #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
| ^~~~~~~~~~~~~~~~~~
net/smc/smc_llc.c:409:9: note: in expansion of macro 'BUILD_BUG_ON_MSG'
409 | BUILD_BUG_ON_MSG(
| ^~~~~~~~~~~~~~~~
include/linux/compiler_types.h:322:45: error: call to '__compiletime_assert_565' declared with attribute error: must adapt SMC_WR_TX_SIZE to sizeof(struct smc_llc_msg); if not all smc_wr upper layer protocols use the same message size any more, must start to set link->wr_tx_sges[i].length on each individual smc_wr_tx_send()
322 | _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
| ^
include/linux/compiler_types.h:303:25: note: in definition of macro '__compiletime_assert'
303 | prefix ## suffix(); \
| ^~~~~~
include/linux/compiler_types.h:322:9: note: in expansion of macro '_compiletime_assert'
322 | _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
| ^~~~~~~~~~~~~~~~~~~
include/linux/build_bug.h:39:37: note: in expansion of macro 'compiletime_assert'
39 | #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
| ^~~~~~~~~~~~~~~~~~
net/smc/smc_llc.c:412:9: note: in expansion of macro 'BUILD_BUG_ON_MSG'
412 | BUILD_BUG_ON_MSG(
| ^~~~~~~~~~~~~~~~
In function 'smc_llc_send_message_wait',
inlined from 'smc_llc_send_link_delete_all' at net/smc/smc_llc.c:1635:8:
net/smc/smc_llc.c:785:9: warning: 'memcpy' reading 60 bytes from a region of size 49 [-Wstringop-overread]
785 | memcpy(wr_buf, llcbuf, sizeof(union smc_llc_msg));
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
net/smc/smc_llc.c: In function 'smc_llc_send_link_delete_all':
net/smc/smc_llc.c:1622:37: note: source object 'delllc' of size 49
1622 | struct smc_llc_msg_del_link delllc = {};
| ^~~~~~


vim +40 net/smc/smc_llc.c

23
24 struct smc_llc_hdr {
25 struct smc_wr_rx_hdr common;
26 union {
27 struct {
28 u8 length; /* 44 */
29 #if defined(__BIG_ENDIAN_BITFIELD)
30 u8 reserved:4,
31 add_link_rej_rsn:4;
32 #elif defined(__LITTLE_ENDIAN_BITFIELD)
33 u8 add_link_rej_rsn:4,
34 reserved:4;
35 #endif
36 };
37 u16 length_v2; /* 44 - 8192*/
38 };
39 u8 flags;
> 40 } __packed; /* format defined in
41 * IBM Shared Memory Communications Version 2
42 * (https://www.ibm.com/support/pages/node/6326337)
43 */
44

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