1. 03 Jun, 2020 1 commit
    • Bodo Stroesser's avatar
      scsi: target: tcmu: Fix size in calls to tcmu_flush_dcache_range · 8c4e0f21
      Bodo Stroesser authored
      1) If remaining ring space before the end of the ring is smaller then the
         next cmd to write, tcmu writes a padding entry which fills the remaining
         space at the end of the ring.
      
         Then tcmu calls tcmu_flush_dcache_range() with the size of struct
         tcmu_cmd_entry as data length to flush.  If the space filled by the
         padding was smaller then tcmu_cmd_entry, tcmu_flush_dcache_range() is
         called for an address range reaching behind the end of the vmalloc'ed
         ring.
      
         tcmu_flush_dcache_range() in a loop calls
         flush_dcache_page(virt_to_page(start)); for every page being part of the
         range. On x86 the line is optimized out by the compiler, as
         flush_dcache_page() is empty on x86.
      
         But I assume the above can cause trouble on other architectures that
         really have a flush_dcache_page().  For paddings only the header part of
         an entry is relevant due to alignment rules the header always fits in
         the remaining space, if padding is needed.  So tcmu_flush_dcache_range()
         can safely be called with sizeof(entry->hdr) as the length here.
      
      2) After it has written a command to cmd ring, tcmu calls
         tcmu_flush_dcache_range() using the size of a struct tcmu_cmd_entry as
         data length to flush.  But if a command needs many iovecs, the real size
         of the command may be bigger then tcmu_cmd_entry, so a part of the
         written command is not flushed then.
      
      Link: https://lore.kernel.org/r/20200528193108.9085-1-bstroesser@ts.fujitsu.comAcked-by: default avatarMike Christie <michael.christie@oracle.com>
      Signed-off-by: default avatarBodo Stroesser <bstroesser@ts.fujitsu.com>
      Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
      8c4e0f21
  2. 27 May, 2020 9 commits
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