Messages in this thread | | | Date | Wed, 11 Dec 2013 07:55:26 +0000 | From | Al Viro <> | Subject | Re: [PATCH -next 2/3] batman-adv: Use seq_overflow |
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On Tue, Dec 10, 2013 at 09:12:43PM -0800, Joe Perches wrote:
> diff --git a/net/batman-adv/gateway_client.c b/net/batman-adv/gateway_client.c > index 2449afa..dfa5d2d 100644 > --- a/net/batman-adv/gateway_client.c > +++ b/net/batman-adv/gateway_client.c > @@ -517,29 +517,28 @@ static int batadv_write_buffer_text(struct batadv_priv *bat_priv, > { > struct batadv_gw_node *curr_gw; > struct batadv_neigh_node *router; > - int ret = -1; > > router = batadv_orig_node_get_router(gw_node->orig_node); > if (!router) > - goto out; > + return -1;
This (as well as the original) means "fail read(2) with -EINVAL", which might or might not be correct behaviour.
> curr_gw = batadv_gw_get_selected_gw_node(bat_priv); > > - ret = seq_printf(seq, "%s %pM (%3i) %pM [%10s]: %u.%u/%u.%u MBit\n", > - (curr_gw == gw_node ? "=>" : " "), > - gw_node->orig_node->orig, > - router->bat_iv.tq_avg, router->addr, > - router->if_incoming->net_dev->name, > - gw_node->bandwidth_down / 10, > - gw_node->bandwidth_down % 10, > - gw_node->bandwidth_up / 10, > - gw_node->bandwidth_up % 10); > + seq_printf(seq, "%s %pM (%3i) %pM [%10s]: %u.%u/%u.%u MBit\n", > + (curr_gw == gw_node ? "=>" : " "), > + gw_node->orig_node->orig, > + router->bat_iv.tq_avg, router->addr, > + router->if_incoming->net_dev->name, > + gw_node->bandwidth_down / 10, > + gw_node->bandwidth_down % 10, > + gw_node->bandwidth_up / 10, > + gw_node->bandwidth_up % 10); > > batadv_neigh_node_free_ref(router); > if (curr_gw) > batadv_gw_node_free_ref(curr_gw); > -out: > - return ret; > + > + return seq_overflow(seq);
... and this is utter junk.
This sucker should return 0. Insufficiently large buffer will be handled by caller, TYVM, if you give that caller a chance to do so. Returning 1 from ->show() is a bug in almost all cases, and definitely so in this one.
Just in case somebody decides that above is worth copying: It Is Not. Original code is buggy, plain and simple. This one trades the older bug ("fail with -EINVAL whenever the buffer is too small") with just as buggy "silently skip an entry entirely whenever the buffer is too small".
Don't Do That.
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