-
Hamish Martin authored
A scenario has been observed where a 'bc_init' message for a link is not retransmitted if it fails to be received by the peer. This leads to the peer never establishing the link fully and it discarding all other data received on the link. In this scenario the message is lost in transit to the peer. The issue is traced to the 'nxt_retr' field of the skb not being initialised for links that aren't a bc_sndlink. This leads to the comparison in tipc_link_advance_transmq() that gates whether to attempt retransmission of a message performing in an undesirable way. Depending on the relative value of 'jiffies', this comparison: time_before(jiffies, TIPC_SKB_CB(skb)->nxt_retr) may return true or false given that 'nxt_retr' remains at the uninitialised value of 0 for non bc_sndlinks. This is most noticeable shortly after boot when jiffies is initialised to a high value (to flush out rollover bugs) and we compare a jiffies of, say, 4294940189 to zero. In that case time_before returns 'true' leading to the skb not being retransmitted. The fix is to ensure that all skbs have a valid 'nxt_retr' time set for them and this is achieved by refactoring the setting of this value into a central function. With this fix, transmission losses of 'bc_init' messages do not stall the link establishment forever because the 'bc_init' message is retransmitted and the link eventually establishes correctly. Fixes: 382f598f ("tipc: reduce duplicate packets for unicast traffic") Acked-by:
Jon Maloy <jmaloy@redhat.com> Signed-off-by:
Hamish Martin <hamish.martin@alliedtelesis.co.nz> Signed-off-by:
David S. Miller <davem@davemloft.net>
a34f8291