Re: [PATCH V4 12/12] scsi: replace sdev->device_busy with sbitmap

On Wed, Nov 18, 2020 at 08:15:47AM +0100, Hannes Reinecke wrote:

Hey Ming,

On 11/18/20 3:35 AM, Ming Lei wrote:

quoted

Hello Kashyap & Sumanesh,

On Mon, Nov 16, 2020 at 07:49:31PM +0800, kernel test robot wrote:

quoted

Hi Ming,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on block/for-next]
[also build test ERROR on mkp-scsi/for-next scsi/for-next v5.10-rc4 next-20201116]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Ming-Lei/blk-mq-scsi-tracking-device-queue-depth-via-sbitmap/20201116-171449
base:   https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git for-next
config: powerpc64-randconfig-r026-20201116 (attached as .config)
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project c044709b8fbea2a9a375e4173a6bd735f6866c0c)
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
         # install powerpc64 cross compiling tool for clang build
         # apt-get install binutils-powerpc64-linux-gnu
         # https://github.com/0day-ci/linux/commit/cc286ae987be50d7b8e152cc80a5ccaa8682e3ff
         git remote add linux-review https://github.com/0day-ci/linux
         git fetch --no-tags linux-review Ming-Lei/blk-mq-scsi-tracking-device-queue-depth-via-sbitmap/20201116-171449
         git checkout cc286ae987be50d7b8e152cc80a5ccaa8682e3ff
         # save the attached .config to linux build tree
         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=powerpc64

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <redacted>

All errors (new ones prefixed by >>):

quoted

quoted

drivers/scsi/megaraid/megaraid_sas_fusion.c:365:41: error: no member named 'device_busy' in 'struct scsi_device'

            sdev_busy = atomic_read(&scmd->device->device_busy);

This new reference to sdev->device_busy is added by recent shared host
tag patch, and according to the comment, you may have planed to convert into
one megaraid internal counter.

         /* TBD - if sml remove device_busy in future, driver
          * should track counter in internal structure.
          */

So can you post one patch? And I am happy to fold it into this series.

Seeing that we already have the accessor 'scsi_device_busy()' it's probably
easier to just use that and not fiddle with driver internals.
See the attached patch.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                Kernel Storage Architect
hare@suse.de                              +49 911 74053 688
SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), Geschäftsführer: Felix Imendörffer

megasas_get_msix_index() is called in .queuecommand() path,
scsi_device_busy() might take more cycles since it has to iterate over
each sbitmap words, especially when the sbitmap depth is high.

I'd suggest Kashyap/Sumanesh to check if there is better way to
deal with it. If not, scsi_device_busy() should be fine.


Thanks,
Ming