linux-kernel - include/soc/fsl/qman.h:383:4: warning: field context_a within 'struct qm_fqd' is less aligned than 'union (unnamed union at include/soc/fsl/qman.h:365:2)' and is usually due to 'struct qm_fqd' being packed, which can lead to unaligned accesses

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Message-ID: <202504091657.OgPuMa8C-lkp@intel.com>
Date: Wed, 9 Apr 2025 16:55:16 +0800
From: kernel test robot <lkp@...el.com>
To: Breno Leitao <leitao@...ian.org>
Cc: oe-kbuild-all@...ts.linux.dev, linux-kernel@...r.kernel.org,
	Jakub Kicinski <kuba@...nel.org>,
	Vladimir Oltean <vladimir.oltean@....com>
Subject: include/soc/fsl/qman.h:383:4: warning: field context_a within
 'struct qm_fqd' is less aligned than 'union (unnamed union at
 include/soc/fsl/qman.h:365:2)' and is usually due to 'struct qm_fqd' being
 packed, which can lead to unaligned accesses

Hi Breno,

FYI, the error/warning still remains.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   a24588245776dafc227243a01bfbeb8a59bafba9
commit: 782fe08e9861d00ce8aca370453dd9ceb9a23d50 soc: fsl: qbman: FSL_DPAA depends on COMPILE_TEST
date:   9 months ago
config: arm-randconfig-r063-20250409 (https://download.01.org/0day-ci/archive/20250409/202504091657.OgPuMa8C-lkp@intel.com/config)
compiler: clang version 16.0.6 (https://github.com/llvm/llvm-project 7cbf1a2591520c2491aa35339f227775f4d3adf6)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250409/202504091657.OgPuMa8C-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@...el.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202504091657.OgPuMa8C-lkp@intel.com/

All warnings (new ones prefixed by >>):

   In file included from drivers/soc/fsl/qbman/qman_ccsr.c:31:
   In file included from drivers/soc/fsl/qbman/qman_priv.h:33:
>> include/soc/fsl/qman.h:383:4: warning: field context_a within 'struct qm_fqd' is less aligned than 'union (unnamed union at include/soc/fsl/qman.h:365:2)' and is usually due to 'struct qm_fqd' being packed, which can lead to unaligned accesses [-Wunaligned-access]
           } context_a;
             ^
   1 warning generated.


vim +383 include/soc/fsl/qman.h

c535e923bb97a4 Claudiu Manoil 2016-09-22  346  
c535e923bb97a4 Claudiu Manoil 2016-09-22  347  struct qm_fqd {
c535e923bb97a4 Claudiu Manoil 2016-09-22  348  	/* _res[6-7], orprws[3-5], oa[2], olws[0-1] */
c535e923bb97a4 Claudiu Manoil 2016-09-22  349  	u8 orpc;
c535e923bb97a4 Claudiu Manoil 2016-09-22  350  	u8 cgid;
c535e923bb97a4 Claudiu Manoil 2016-09-22  351  	__be16 fq_ctrl;	/* See QM_FQCTRL_<...> */
c535e923bb97a4 Claudiu Manoil 2016-09-22  352  	__be16 dest_wq;	/* channel[3-15], wq[0-2] */
c535e923bb97a4 Claudiu Manoil 2016-09-22  353  	__be16 ics_cred; /* 15-bit */
c535e923bb97a4 Claudiu Manoil 2016-09-22  354  	/*
c535e923bb97a4 Claudiu Manoil 2016-09-22  355  	 * For "Initialize Frame Queue" commands, the write-enable mask
c535e923bb97a4 Claudiu Manoil 2016-09-22  356  	 * determines whether 'td' or 'oac_init' is observed. For query
c535e923bb97a4 Claudiu Manoil 2016-09-22  357  	 * commands, this field is always 'td', and 'oac_query' (below) reflects
c535e923bb97a4 Claudiu Manoil 2016-09-22  358  	 * the Overhead ACcounting values.
c535e923bb97a4 Claudiu Manoil 2016-09-22  359  	 */
c535e923bb97a4 Claudiu Manoil 2016-09-22  360  	union {
c535e923bb97a4 Claudiu Manoil 2016-09-22  361  		__be16 td; /* "Taildrop": _res[13-15], mant[5-12], exp[0-4] */
c535e923bb97a4 Claudiu Manoil 2016-09-22  362  		struct qm_fqd_oac oac_init;
c535e923bb97a4 Claudiu Manoil 2016-09-22  363  	};
c535e923bb97a4 Claudiu Manoil 2016-09-22  364  	__be32 context_b;
c535e923bb97a4 Claudiu Manoil 2016-09-22  365  	union {
c535e923bb97a4 Claudiu Manoil 2016-09-22  366  		/* Treat it as 64-bit opaque */
c535e923bb97a4 Claudiu Manoil 2016-09-22  367  		__be64 opaque;
c535e923bb97a4 Claudiu Manoil 2016-09-22  368  		struct {
c535e923bb97a4 Claudiu Manoil 2016-09-22  369  			__be32 hi;
c535e923bb97a4 Claudiu Manoil 2016-09-22  370  			__be32 lo;
c535e923bb97a4 Claudiu Manoil 2016-09-22  371  		};
c535e923bb97a4 Claudiu Manoil 2016-09-22  372  		/* Treat it as s/w portal stashing config */
c535e923bb97a4 Claudiu Manoil 2016-09-22  373  		/* see "FQD Context_A field used for [...]" */
c535e923bb97a4 Claudiu Manoil 2016-09-22  374  		struct {
c535e923bb97a4 Claudiu Manoil 2016-09-22  375  			struct qm_fqd_stashing stashing;
c535e923bb97a4 Claudiu Manoil 2016-09-22  376  			/*
c535e923bb97a4 Claudiu Manoil 2016-09-22  377  			 * 48-bit address of FQ context to
c535e923bb97a4 Claudiu Manoil 2016-09-22  378  			 * stash, must be cacheline-aligned
c535e923bb97a4 Claudiu Manoil 2016-09-22  379  			 */
c535e923bb97a4 Claudiu Manoil 2016-09-22  380  			__be16 context_hi;
c535e923bb97a4 Claudiu Manoil 2016-09-22  381  			__be32 context_lo;
c535e923bb97a4 Claudiu Manoil 2016-09-22  382  		} __packed;
c535e923bb97a4 Claudiu Manoil 2016-09-22 @383  	} context_a;
c535e923bb97a4 Claudiu Manoil 2016-09-22  384  	struct qm_fqd_oac oac_query;
c535e923bb97a4 Claudiu Manoil 2016-09-22  385  } __packed;
c535e923bb97a4 Claudiu Manoil 2016-09-22  386  

:::::: The code at line 383 was first introduced by commit
:::::: c535e923bb97a4b361e89a6383693482057f8b0c soc/fsl: Introduce DPAA 1.x QMan device driver

:::::: TO: Claudiu Manoil <claudiu.manoil@....com>
:::::: CC: Scott Wood <oss@...error.net>

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki