linux-kernel - RE: [PATCH v37 3/4] scsi: ufs: Prepare HPB read for cached sub-region

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Message-ID: <d38fbfa83d1f421c8a0d201a3cb6dce3@sk.com>
Date:   Sun, 13 Jun 2021 23:40:04 +0000
From:   정요한(JOUNG YOHAN) Mobile SE 
        <yohan.joung@...com>
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        정요한(JOUNG YOHAN) Mobile SE 
        <yohan.joung@...com>
Subject: RE: [PATCH v37 3/4] scsi: ufs: Prepare HPB read for cached sub-region

> > >+      /*
> > >+       * If the region state is active, mctx must be allocated.
> > >+       * In this case, check whether the region is evicted or
> > >+       * mctx allcation fail.
> > >+       */
> > >+      if (unlikely(!srgn->mctx)) {
> > >+              dev_err(&hpb->sdev_ufs_lu->sdev_dev,
> > >+                      "no mctx in region %d subregion %d.\n",
> > >+                      srgn->rgn_idx, srgn->srgn_idx);
> > >+              return true;
> > >+      }
> > >+
> > >+      if ((srgn_offset + cnt) > bitmap_len)
> > >+              bit_len = bitmap_len - srgn_offset;
> > >+      else
> > >+              bit_len = cnt;
> > >+
> > >+      if (find_next_bit(srgn->mctx->ppn_dirty, bitmap_len,
> > >+                        srgn_offset) < bit_len + srgn_offset)
> > >+              return true;
> > >+
> > 
> > It seems unnecessary to search through bitmap_len
> > How about searching by transfer size?
> > 
> > if (find_next_bit(srgn->mctx->ppn_dirty,
> >               bit_len + srgn_offset, srgn_offset) < bit_len + srgn_offset)
> Isn't bit_len should be used for size, and not bit_len + srgn_offset ?

then find_next_bit checks from start to bit_len.
find_next_bit stops checking if start is greater than bit_len.
it does not check for dirty as transfer_size.

Thanks
Yohan

> 
> Thanks,
> Avri
> 
> > 
> > Thanks
> > Yohan