[PATCH resent] Documentation: rw_lock lessons learned

[William Allen Simpson <william.allen.simpson@gmail.com>]

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In recent weeks, two different network projects erroneously
strayed down the rw_lock path.  Update the Documentation
based upon comments in those threads.

Signed-off-by: William.Allen.Simpson@gmail.com
---
   Documentation/spinlocks.txt |   14 ++++++++++++++
   1 files changed, 14 insertions(+), 0 deletions(-)


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diff --git a/Documentation/spinlocks.txt b/Documentation/spinlocks.txt
index 619699d..c112052 100644
--- a/Documentation/spinlocks.txt
+++ b/Documentation/spinlocks.txt
@@ -233,4 +233,18 @@ indeed), while write-locks need to protect themselves against interrupts.
 
 		Linus
 
+----
+
+The implications of spin_locks on memory are further described in:
+
+  Documentation/memory-barriers.txt
+    (5) LOCK operations.
+    (6) UNLOCK operations.
+
+----
+
+We are working hard to remove reader-writer spinlocks (rw_lock) from the
+network stack, so please don't add a new one.  Instead, see:
+
+  Documentation/RCU/rcu.txt
 
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1.6.3.3