tipc: Add missing spinlock in name table display code

This patch ensures that the display code that traverses the
publication lists belonging to a name table entry take its
associated spinlock, to protect against a possible change to
one of its "head of list" pointers caused by a simultaneous
name table lookup operation by another thread of control.

Signed-off-by: Allan Stephens <allan.stephens@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/tipc/name_table.c b/net/tipc/name_table.c
index 4455f13cfaf68f632e48b42db877b42a704216dd..096f7bd240a0307267c30dba909b7fad2fac8471 100644 (file)
--- a/net/tipc/name_table.c
+++ b/net/tipc/name_table.c
@@ -74,7 +74,7 @@ struct sub_seq {
  * @first_free: array index of first unused sub-sequence entry
  * @ns_list: links to adjacent name sequences in hash chain
  * @subscriptions: list of subscriptions for this 'type'
- * @lock: spinlock controlling access to name sequence structure
+ * @lock: spinlock controlling access to publication lists of all sub-sequences
  */
 
 struct name_seq {
@@ -918,7 +918,9 @@ static void nameseq_list(struct name_seq *seq, struct print_buf *buf, u32 depth,
        for (sseq = seq->sseqs; sseq != &seq->sseqs[seq->first_free]; sseq++) {
                if ((lowbound <= sseq->upper) && (upbound >= sseq->lower)) {
                        tipc_printf(buf, "%s ", typearea);
+                       spin_lock_bh(&seq->lock);
                        subseq_list(sseq, buf, depth, index);
+                       spin_unlock_bh(&seq->lock);
                        sprintf(typearea, "%10s", " ");
                }
        }