Re: [PATCH] futex: Ensure get_futex_key_refs() always implies a barrier

[Davidlohr Bueso]

On Sat, 2014-10-18 at 14:32 -0500, Darren Hart wrote:
> Which is not incomplete (lacking the explicit smp_mb()) added by this
> patch. Perhaps the MB implementation of get_futex_key_refs() need not be
> explicitly enumerated here?

Agreed, how about this:

diff --git a/kernel/futex.c b/kernel/futex.c
index 21f7e41..7a0805a 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -143,9 +143,8 @@
  *
  * Where (A) orders the waiters increment and the futex value read through
  * atomic operations (see hb_waiters_inc) and where (B) orders the write
- * to futex and the waiters read -- this is done by the barriers in
- * get_futex_key_refs(), through either ihold or atomic_inc, depending on the
- * futex type.
+ * to futex and the waiters read -- this is done by the barriers for both
+ * shared and private futexes in get_futex_key_refs().
  *
  * This yields the following case (where X:=waiters, Y:=futex):
  *



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