locking/x86/xen: Use try_cmpxchg() in xen_alloc_p2m_entry()

Use try_cmpxchg() instead of cmpxchg(*ptr, old, new) == old.

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

Also, try_cmpxchg() implicitly assigns old *ptr value to "old"
when CMPXCHG fails. There is no need to explicitly assign
old *ptr value to the temporary, which can simplify the
surrounding source code.

No functional change intended.

Signed-off-by: Uros Bizjak <[email protected]>
Reviewed-by: Juergen Gross <[email protected]>
Cc: Juergen Gross <[email protected]>
Cc: Boris Ostrovsky <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Juergen Gross <[email protected]>

0 files changed, 0 insertions, 0 deletions