NOT IN MAINLINE Linus it's go or drop it?
-- Thanks, Oliver
--- Begin Message ---Additional Comment #103 From Andrea Arcangeli 2004-10-15 19:41 the last patch I attached is the safest I believe. I'm not sure if a lock_unlock or lock_unlock is always guaranteed to happen after the I/O, and this makes sure no race can happen anymore. --- fs/bio.c | 9 +++++++++ 1 file changed, 9 insertions(+) --- a/fs/bio.c 2007-07-08 19:32:17.000000000 -0400 +++ b/fs/bio.c 2007-08-27 14:01:21.000000000 -0400 @@ -1028,6 +1028,15 @@ void bio_endio(struct bio *bio, unsigned bio->bi_size -= bytes_done; bio->bi_sector += (bytes_done >> 9); + if (bio_data_dir(bio) == READ) + /* + * If the current cpu has written to the page by hand + * without dma, we must enforce ordering to be sure + * this written data will be visible before we expose + * the page contents to other cpus (for example with + * a set_pte). + */ + smp_wmb(); if (bio->bi_end_io) bio->bi_end_io(bio, bytes_done, error); }
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