afs: Fix missing lock when replacing VL server list (6b8812fc) · Commits · 戴 / test

When afs_update_cell() replaces the cell->vl_servers list, it uses RCU protocol so that proc is protected, but doesn't take ->vl_servers_lock to protect afs_start_vl_iteration() (which does actually take a shared lock). Fix this by making afs_update_cell() take an exclusive lock when replacing ->vl_servers. Fixes: ("afs: Implement VL server rotation") Signed-off-by:

David Howells <dhowells@redhat.com>

fs/afs/cell.c

+2 −3

Original line number	Diff line number	Diff line
		@@ -404,12 +404,11 @@ static void afs_update_cell(struct afs_cell *cell)
		clear_bit(AFS_CELL_FL_DNS_FAIL, &cell->flags);
		clear_bit(AFS_CELL_FL_NOT_FOUND, &cell->flags);

		/* Exclusion on changing vl_addrs is achieved by a
		* non-reentrant work item.
		*/
		write_lock(&cell->vl_servers_lock);
		old = rcu_dereference_protected(cell->vl_servers, true);
		rcu_assign_pointer(cell->vl_servers, vllist);
		cell->dns_expiry = expiry;
		write_unlock(&cell->vl_servers_lock);

		if (old)
		afs_put_vlserverlist(cell->net, old);

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