On Thu, 28 May 2020 21:31:08 +0200, Bodo Stroesser wrote:
> 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.
>
> [...]
Applied to 5.8/scsi-queue, thanks!
[1/1] scsi: target: tcmu: Fix size in calls to tcmu_flush_dcache_range
https://git.kernel.org/mkp/scsi/c/8c4e0f212398
--
Martin K. Petersen Oracle Linux Engineering
