[PATCH] remove generic__raw_read_trylock()

If the cpu has the lock held for write, is interrupted, and the interrupt
handler calls read_trylock(), it's an instant deadlock.

Now, Dave Miller has subsequently pointed out that we don't have any
situations where this can occur.  Nevertheless, we should delete
generic__raw_read_lock (and its associated EXPORT to make Arjan happy) so that
nobody thinks they can use it.
Acked-by: N"David S. Miller" <davem@davemloft.net>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

kernel/spinlock.c

@@ -21,17 +21,6 @@
 #include <linux/debug_locks.h>
 #include <linux/module.h>
 
-/*
- * Generic declaration of the raw read_trylock() function,
- * architectures are supposed to optimize this:
- */
-int __lockfunc generic__raw_read_trylock(raw_rwlock_t *lock)
-{
-	__raw_read_lock(lock);
-	return 1;
-}
-EXPORT_SYMBOL(generic__raw_read_trylock);
-
 int __lockfunc _spin_trylock(spinlock_t *lock)
 {
 	preempt_disable();