iommu/vt-d: Use try_cmpxchg64{,_local}() in iommu.c

Replace this pattern in iommu.c:

    cmpxchg64{,_local}(*ptr, 0, new) != 0

... with the simpler and faster:

    !try_cmpxchg64{,_local}(*ptr, &tmp, new)

The x86 CMPXCHG instruction returns success in the ZF flag, so this change
saves a compare after the CMPXCHG.

No functional change intended.

Signed-off-by: Uros Bizjak <[email protected]>
Cc: David Woodhouse <[email protected]>
Cc: Lu Baolu <[email protected]>
Cc: Joerg Roedel <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Robin Murphy <[email protected]>
Reviewed-by: Jason Gunthorpe <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Lu Baolu <[email protected]>
Signed-off-by: Joerg Roedel <[email protected]>

0 files changed, 0 insertions, 0 deletions