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Commit b34bd06e authored by Paul E. McKenney's avatar Paul E. McKenney Committed by Linus Torvalds
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bpqether: fix rcu usage 



The rcu_dereference() primitive needs to be applied to an l-value in order to
ensure that compiler writers don't get an opportunity to apply reordering
optimizations that could result in multiple fetches or in other misbehavior.
This patch pulls the rcu_dereference() calls in bpq_seq_next() up to the point
at which the fetched pointers are still l-values, rather than after
list_entry() has transformed them into r-values.

Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Jeff Garzik <jeff@garzik.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 7be77e20

drivers/net/hamradio/bpqether.c

+3 −3
Original line number Diff line number Diff line
@@ -413,12 +413,12 @@ static void *bpq_seq_next(struct seq_file *seq, void *v, loff_t *pos) 
	++*pos;



	if (v == SEQ_START_TOKEN)

		p = bpq_devices.next;

		p = rcu_dereference(bpq_devices.next);

	else

		p = ((struct bpqdev *)v)->bpq_list.next;

		p = rcu_dereference(((struct bpqdev *)v)->bpq_list.next);



	return (p == &bpq_devices) ? NULL 

		: rcu_dereference(list_entry(p, struct bpqdev, bpq_list));

		: list_entry(p, struct bpqdev, bpq_list);

}



static void bpq_seq_stop(struct seq_file *seq, void *v)