• Linus Torvalds's avatar
    dma-debug: remove debug_dma_assert_idle() function · 5848dc5b
    Linus Torvalds authored
    This remoes the code from the COW path to call debug_dma_assert_idle(),
    which was added many years ago.
    
    Google shows that it hasn't caught anything in the 6+ years we've had it
    apart from a false positive, and Hugh just noticed how it had a very
    unfortunate spinlock serialization in the COW path.
    
    He fixed that issue the previous commit (a85ffd59: "dma-debug: fix
    debug_dma_assert_idle(), use rcu_read_lock()"), but let's see if anybody
    even notices when we remove this function entirely.
    
    NOTE! We keep the dma tracking infrastructure that was added by the
    commit that introduced it.  Partly to make it easier to resurrect this
    debug code if we ever deside to, and partly because that tracking by pfn
    and offset looks quite reasonable.
    
    The problem with this debug code was simply that it was expensive and
    didn't seem worth it, not that it was wrong per se.
    Acked-by: default avatarDan Williams <dan.j.williams@intel.com>
    Acked-by: default avatarChristoph Hellwig <hch@lst.de>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    5848dc5b
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