[Cluster-devel] [dlm:next 14/16] fs/dlm/midcomms.c:541:25: sparse: sparse: cast to restricted __le32

[Rong Chen]

On 5/26/21 11:20 PM, Alexander Ahring Oder Aring wrote:
> Hi,
>
> before somebody tried to fix it. Some comments, see below.
>
> On Tue, May 25, 2021 at 5:17 PM kernel test robot <lkp at intel.com> wrote:
>> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/teigland/linux-dlm.git next
>> head:   706474fbc5fedd7799b488962aad3541b235165b
>> commit: 489d8e559c6596eb08e16447d9830bc39afbe54e [14/16] fs: dlm: add reliable connection if reconnect
>> config: m68k-randconfig-s031-20210525 (attached as .config)
>> compiler: m68k-linux-gcc (GCC) 9.3.0
>> reproduce:
>>          wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
>>          chmod +x ~/bin/make.cross
>>          # apt-get install sparse
>>          # sparse version: v0.6.3-341-g8af24329-dirty
>>          # https://git.kernel.org/pub/scm/linux/kernel/git/teigland/linux-dlm.git/commit/?id=489d8e559c6596eb08e16447d9830bc39afbe54e
>>          git remote add dlm https://git.kernel.org/pub/scm/linux/kernel/git/teigland/linux-dlm.git
>>          git fetch --no-tags dlm next
>>          git checkout 489d8e559c6596eb08e16447d9830bc39afbe54e
>>          # save the attached .config to linux build tree
>>          COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' W=1 ARCH=m68k
>>
>> If you fix the issue, kindly add following tag as appropriate
>> Reported-by: kernel test robot <lkp at intel.com>
>>
>>
>> sparse warnings: (new ones prefixed by >>)
>>>> fs/dlm/midcomms.c:541:25: sparse: sparse: cast to restricted __le32
>>>> fs/dlm/midcomms.c:541:25: sparse: sparse: cast to restricted __le32
>>>> fs/dlm/midcomms.c:541:25: sparse: sparse: cast to restricted __le32
>>>> fs/dlm/midcomms.c:541:25: sparse: sparse: cast to restricted __le32
>>>> fs/dlm/midcomms.c:541:25: sparse: sparse: cast to restricted __le32
>>>> fs/dlm/midcomms.c:541:25: sparse: sparse: cast to restricted __le32
>>     fs/dlm/midcomms.c:634:19: sparse: sparse: cast to restricted __le16
>>     fs/dlm/midcomms.c:634:19: sparse: sparse: cast to restricted __le16
>>     fs/dlm/midcomms.c:634:19: sparse: sparse: cast to restricted __le16
>>     fs/dlm/midcomms.c:634:19: sparse: sparse: cast to restricted __le16
>>     fs/dlm/midcomms.c:636:16: sparse: sparse: cast to restricted __le16
>>     fs/dlm/midcomms.c:636:16: sparse: sparse: cast to restricted __le16
>>     fs/dlm/midcomms.c:636:16: sparse: sparse: cast to restricted __le16
>>     fs/dlm/midcomms.c:636:16: sparse: sparse: cast to restricted __le16
>>     fs/dlm/midcomms.c:674:27: sparse: sparse: cast to restricted __le16
>>     fs/dlm/midcomms.c:674:27: sparse: sparse: cast to restricted __le16
>>     fs/dlm/midcomms.c:674:27: sparse: sparse: cast to restricted __le16
>>     fs/dlm/midcomms.c:674:27: sparse: sparse: cast to restricted __le16
>>     fs/dlm/midcomms.c:693:25: sparse: sparse: cast to restricted __le32
>>     fs/dlm/midcomms.c:693:25: sparse: sparse: cast to restricted __le32
>>     fs/dlm/midcomms.c:693:25: sparse: sparse: cast to restricted __le32
>>     fs/dlm/midcomms.c:693:25: sparse: sparse: cast to restricted __le32
>>     fs/dlm/midcomms.c:693:25: sparse: sparse: cast to restricted __le32
>>     fs/dlm/midcomms.c:693:25: sparse: sparse: cast to restricted __le32
>>     fs/dlm/midcomms.c:703:25: sparse: sparse: cast to restricted __le32
>>     fs/dlm/midcomms.c:703:25: sparse: sparse: cast to restricted __le32
>>     fs/dlm/midcomms.c:703:25: sparse: sparse: cast to restricted __le32
>>     fs/dlm/midcomms.c:703:25: sparse: sparse: cast to restricted __le32
>>     fs/dlm/midcomms.c:703:25: sparse: sparse: cast to restricted __le32
>>     fs/dlm/midcomms.c:703:25: sparse: sparse: cast to restricted __le32
>>     fs/dlm/midcomms.c:712:23: sparse: sparse: cast to restricted __le32
>>     fs/dlm/midcomms.c:712:23: sparse: sparse: cast to restricted __le32
>>     fs/dlm/midcomms.c:712:23: sparse: sparse: cast to restricted __le32
>>     fs/dlm/midcomms.c:712:23: sparse: sparse: cast to restricted __le32
>>     fs/dlm/midcomms.c:712:23: sparse: sparse: cast to restricted __le32
>>     fs/dlm/midcomms.c:712:23: sparse: sparse: cast to restricted __le32
>>     fs/dlm/midcomms.c:722:42: sparse: sparse: cast to restricted __le16
>>     fs/dlm/midcomms.c:722:42: sparse: sparse: cast to restricted __le16
>>     fs/dlm/midcomms.c:722:42: sparse: sparse: cast to restricted __le16
>>     fs/dlm/midcomms.c:722:42: sparse: sparse: cast to restricted __le16
>>     fs/dlm/midcomms.c:725:26: sparse: sparse: cast to restricted __le16
>>     fs/dlm/midcomms.c:725:26: sparse: sparse: cast to restricted __le16
>>     fs/dlm/midcomms.c:725:26: sparse: sparse: cast to restricted __le16
>>     fs/dlm/midcomms.c:725:26: sparse: sparse: cast to restricted __le16
>>     fs/dlm/midcomms.c:760:23: sparse: sparse: cast to restricted __le32
>>     fs/dlm/midcomms.c:760:23: sparse: sparse: cast to restricted __le32
>>     fs/dlm/midcomms.c:760:23: sparse: sparse: cast to restricted __le32
>>     fs/dlm/midcomms.c:760:23: sparse: sparse: cast to restricted __le32
>>     fs/dlm/midcomms.c:760:23: sparse: sparse: cast to restricted __le32
>>     fs/dlm/midcomms.c:760:23: sparse: sparse: cast to restricted __le32
>>     fs/dlm/midcomms.c:794:27: sparse: sparse: cast to restricted __le16
>>     fs/dlm/midcomms.c:794:27: sparse: sparse: cast to restricted __le16
>>     fs/dlm/midcomms.c:794:27: sparse: sparse: cast to restricted __le16
>>     fs/dlm/midcomms.c:794:27: sparse: sparse: cast to restricted __le16
>>     fs/dlm/midcomms.c:854:26: sparse: sparse: cast to restricted __le16
>>     fs/dlm/midcomms.c:854:26: sparse: sparse: cast to restricted __le16
>>     fs/dlm/midcomms.c:854:26: sparse: sparse: cast to restricted __le16
>>     fs/dlm/midcomms.c:854:26: sparse: sparse: cast to restricted __le16
>>     fs/dlm/midcomms.c:868:25: sparse: sparse: cast to restricted __le32
>>     fs/dlm/midcomms.c:868:25: sparse: sparse: cast to restricted __le32
>>     fs/dlm/midcomms.c:868:25: sparse: sparse: cast to restricted __le32
>>     fs/dlm/midcomms.c:868:25: sparse: sparse: cast to restricted __le32
>>     fs/dlm/midcomms.c:868:25: sparse: sparse: cast to restricted __le32
>>     fs/dlm/midcomms.c:868:25: sparse: sparse: cast to restricted __le32
>>     fs/dlm/midcomms.c:876:25: sparse: sparse: cast to restricted __le32
>>     fs/dlm/midcomms.c:876:25: sparse: sparse: cast to restricted __le32
>>     fs/dlm/midcomms.c:876:25: sparse: sparse: cast to restricted __le32
>>     fs/dlm/midcomms.c:876:25: sparse: sparse: cast to restricted __le32
>>     fs/dlm/midcomms.c:876:25: sparse: sparse: cast to restricted __le32
>>     fs/dlm/midcomms.c:876:25: sparse: sparse: cast to restricted __le32
> We can ignore it for now. The dlm code does some endian transfer with
> cpu_to_leFOO() and vice versa and never uses any __leFOO define. See
> header_in()/out() functions. Sure somebody is welcome to send patches
> and make sparse happy but it requires more code changes.
>
>>>> fs/dlm/midcomms.c:969:20: sparse: sparse: context imbalance in 'dlm_midcomms_get_mhandle' - wrong count at exit
>>     fs/dlm/midcomms.c:1045:33: sparse: sparse: context imbalance in 'dlm_midcomms_commit_mhandle' - unexpected unlock
>>
> That is false positive, we always assume a successful get_mhandle()
> triggers a commit_mhandle() and we keep the srcu nodes locked so that
> a reference isn't be freed, avoiding an extra lookup. There is also no
> logic to revert an allocated buffer, the complicated part will be to
> rearrange the buffer in the page buffer then which seems to be quite
> complex, so if there is a get_mhandle() there must be a
> commit_mhandle(). That was always be the case.
>
> - Alex
>

Hi Alex,

yes, the 'context imbalance' warning is false positive in most cases,
we can't ignore it because it can find real issue occasionally, thanks 
for the
detailed explanation.

Best Regards,
Rong Chen