Messages in this thread | | | Date | Wed, 17 Oct 2007 20:02:19 +0200 | From | Jens Axboe <> | Subject | Re: [bug] block subsystem related crash with latest -git |
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On Wed, Oct 17 2007, Linus Torvalds wrote: > > > On Wed, 17 Oct 2007, Jens Axboe wrote: > > > > OK, it is fine, as long as the sglist is cleared initially. And I don't > > think there's anyway around that, clearly I didn't think long enough > > before including the memset() removal from Tomo. > > Ok, I think that one-liner fixes the real bug. > > But I think the rest of your changes are simply bad. > > The fix to block/ll_rw_block.c should likely be something like the > appended instead: > > - remove the "memset()" you had added earlier. It's bogus. It cannot be > the right thing. If the sg list wasn't initialized correctly much > earlier, trying to initialize it late is pointless - it contains crap.
It's required to clear output members (like dma_len and so on), since some of the IOMU code really wants that initialized.
> - the old code was fine, but let's initialize "sg" to NULL to make it > clear that the initial value of sg is pointless, and only "next_sg" > matters (since sg had better be assigned from that).
If you prefer the old next_sg approach to my alternative, that is fine with me. But we do need the memset().
-- Jens Axboe
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