> -----Original Message----- > From: Parthasarathy Bhuvaragan > Sent: Thursday, 06 October, 2016 04:35 > To: Jon Maloy <jon.ma...@ericsson.com>; tipc-discussion@lists.sourceforge.net; > ma...@donjonn.com; Ying Xue <ying....@windriver.com> > Subject: Re: [PATCH net v1 2/3] tipc: return early for non-blocking sockets > at link > congestion > > > > On 10/05/2016 05:25 PM, Jon Maloy wrote: > > > > > >> -----Original Message----- > >> From: Parthasarathy Bhuvaragan > >> Sent: Wednesday, 05 October, 2016 04:18 > >> To: Jon Maloy <jon.ma...@ericsson.com>; tipc- > discuss...@lists.sourceforge.net; > >> ma...@donjonn.com; Ying Xue <ying....@windriver.com> > >> Subject: Re: [PATCH net v1 2/3] tipc: return early for non-blocking > >> sockets at > link > >> congestion > >> > >> On 10/04/2016 09:26 PM, Jon Maloy wrote: > >>> > >>> > >>>> -----Original Message----- > >>>> From: Parthasarathy Bhuvaragan > >>>> Sent: Tuesday, 04 October, 2016 08:29 > >>>> To: tipc-discussion@lists.sourceforge.net; Jon Maloy > >> <jon.ma...@ericsson.com>; > >>>> ma...@donjonn.com; Ying Xue <ying....@windriver.com> > >>>> Subject: [PATCH net v1 2/3] tipc: return early for non-blocking sockets > >>>> at > link > >>>> congestion > >>>> > >>>> Until now, in stream/mcast send() we pass the message to the link > >>>> layer even when the link is congested and add the socket to the > >>>> link's wakeup queue. This is unnecessary for non-blocking sockets. > >>>> If a socket is set to non-blocking and sends multicast with zero > >>>> back off time while receiving EAGAIN, we exhaust the memory. > >>>> > >>>> In this commit, we return immediately at stream/mcast send() for > >>>> non-blocking sockets. > >>>> > >>>> Signed-off-by: Parthasarathy Bhuvaragan > >>>> <parthasarathy.bhuvara...@ericsson.com> > >>>> --- > >>>> net/tipc/socket.c | 6 ++++++ > >>>> 1 file changed, 6 insertions(+) > >>>> > >>>> diff --git a/net/tipc/socket.c b/net/tipc/socket.c > >>>> index f9f5f3c3dab5..adf3e6ecf61e 100644 > >>>> --- a/net/tipc/socket.c > >>>> +++ b/net/tipc/socket.c > >>>> @@ -697,6 +697,9 @@ static int tipc_sendmcast(struct socket *sock, > >>>> struct > >>>> tipc_name_seq *seq, > >>>> uint mtu; > >>>> int rc; > >>>> > >>>> + if (!timeo && tsk->link_cong) > >>>> + return -ELINKCONG; > >>> > >>> Why is the !timeo test needed ? > >> [partha] When a socket with a non-zero sndtimeo experiences congestion, > >> the socket is put to sleep for the specified duration and is woken if > >> congestion ceases and we attempt to transmit the buffer. If we had > >> experienced congestion for the entire duration, then we return > >> ELINKLCONG to the user. Hence I can return immediately only when timeout > >> == 0. > > > > Are you saying that we can have non-blocking sockets with a non-zero > > timeout? > > I guess my point was that if the socket is blocking, i.e., the timeout is > > != 0, you > will never get into this second call in the first place, since the socket > already is > blocked if sk->link_cong is true. Hence no need for testing on the timer > value. > Unsure if this is valid with multiple threads though. > [partha] zero timeout means that either the socket is non-blocking or > this message has MSG_DONTWAIT flag set (irrespective of the socket being > blocking or non-blocking). From the timeout I derive that this user has > no intention of waiting. > For multi-threaded applications, each thread can call a blocking > sendmsg() or call sendmsg() with MSG_DONTWAIT flag or use several thread > instances of both. The fix should cover all the above.
Ok. It seems I haven't fully understood this aspect of the API. Acked-by: jon > > > >>> > >>> ///jon > >>> > >>>> + > >>>> msg_set_type(mhdr, TIPC_MCAST_MSG); > >>>> msg_set_lookup_scope(mhdr, TIPC_CLUSTER_SCOPE); > >>>> msg_set_destport(mhdr, 0); > >>>> @@ -1072,6 +1075,9 @@ static int __tipc_send_stream(struct socket *sock, > >>>> struct msghdr *m, size_t dsz) > >>>> } > >>>> > >>>> timeo = sock_sndtimeo(sk, m->msg_flags & MSG_DONTWAIT); > >>>> + if (!timeo && tsk->link_cong) > >>>> + return -ELINKCONG; > >>>> + > >>>> dnode = tsk_peer_node(tsk); > >>>> skb_queue_head_init(&pktchain); > >>>> > >>>> -- > >>>> 2.1.4 > >>> ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, SlashDot.org! http://sdm.link/slashdot _______________________________________________ tipc-discussion mailing list tipc-discussion@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/tipc-discussion
