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Message-ID: <A2BAEFC30C8FD34388F02C9B3121859D1C2BED37@eusaamb103.ericsson.se> Date: Mon, 25 Aug 2014 21:17:31 +0000 From: Jon Maloy <jon.maloy@...csson.com> To: Erik Hugne <erik.hugne@...csson.com>, "ying.xue@...driver.com" <ying.xue@...driver.com>, Richard Alpe <richard.alpe@...csson.com>, "netdev@...r.kernel.org" <netdev@...r.kernel.org> CC: "tipc-discussion@...ts.sourceforge.net" <tipc-discussion@...ts.sourceforge.net> Subject: RE: [PATCH net-next 2/2] tipc: add name distributor resiliency queue > -----Original Message----- > From: Erik Hugne > Sent: August-25-14 10:54 AM > To: Jon Maloy; ying.xue@...driver.com; Richard Alpe; > netdev@...r.kernel.org > Cc: tipc-discussion@...ts.sourceforge.net; Erik Hugne > Subject: [PATCH net-next 2/2] tipc: add name distributor resiliency queue > > From: Erik Hugne <erik.hugne@...csson.com> > > TIPC name table updates are distributed asynchronously in a cluster, entailing > a risk of certain race conditions. E.g., if two nodes simultaneously issue > conflicting (overlapping) publications, this may not be detected until both > publications have reached a third node, in which case one of the publications > will be silently dropped on that node. Hence, we end up with an inconsistent > name table. > > In most cases this conflict is just a temporary race, e.g., one node is issuing a > publication under the assumption that a previous, conflicting, publication has > already been withdrawn by the other node. > However, because of the (rtt related) distributed update delay, this may not > yet hold true on all nodes. The symptom of this failure is a syslog message: > "tipc: Cannot publish {%u,%u,%u}, overlap error". > > In this commit we add a resiliency queue at the receiving end of the name > table distributor. When insertion of an arriving publication fails, we retain it in > this queue for a short amount of time, assuming that another update will > arrive very soon and clear the conflict. If so happens, we insert the > publication, otherwise we drop it. > > The (configurable) retention value defaults to 2000 ms. Knowing from > experience that the situation described above is extremely rare, there is no > risk that the queue will accumulate any large number of items. > > Signed-off-by: Erik Hugne <erik.hugne@...csson.com> > Signed-off-by: Jon Maloy <jon.maloy@...csson.com> > --- > Documentation/sysctl/net.txt | 14 +++++++++ > net/tipc/core.h | 1 + > net/tipc/name_distr.c | 69 > ++++++++++++++++++++++++++++++++++++++++++-- > net/tipc/name_distr.h | 1 + > net/tipc/name_table.c | 8 ++--- > net/tipc/sysctl.c | 7 +++++ > 6 files changed, 93 insertions(+), 7 deletions(-) > > diff --git a/Documentation/sysctl/net.txt b/Documentation/sysctl/net.txt > index 9a0319a..89ce54e 100644 > --- a/Documentation/sysctl/net.txt > +++ b/Documentation/sysctl/net.txt > @@ -241,6 +241,9 @@ address of the router (or Connected) for internal > networks. > 6. TIPC > ------------------------------------------------------- > > +tipc_rmem > +---------- > + > The TIPC protocol now has a tunable for the receive memory, similar to the > tcp_rmem - i.e. a vector of 3 INTEGERs: (min, default, max) > > @@ -252,3 +255,14 @@ The max value is set to CONN_OVERLOAD_LIMIT, > and the default and min values are scaled (shifted) versions of that same > value. Note that the min value is not at this point in time used in any > meaningful way, but the triplet is preserved in order to be consistent with > things like tcp_rmem. > + > +named_timeout > +-------------- > + > +TIPC name table updates are distributed asynchronous asynchronously >+ in a cluster, without any form of transaction handling. This means that different race scenarios are possible. One such is that a name withdrawal sent out by one node and received by a another node may arrive after a second, overlapping name publication already has been accepted from a third node, although the conflicting updates originally may have been issued in the correct sequential order. > +If named_timeout is nonzero, failed topology updates will be placed on > +a defer queue until another event arrives that clears the error, or > +until the timeout expires. Value is in milliseconds. > diff --git a/net/tipc/core.h b/net/tipc/core.h index d2607a8..f773b14 100644 > --- a/net/tipc/core.h > +++ b/net/tipc/core.h > @@ -81,6 +81,7 @@ extern u32 tipc_own_addr __read_mostly; extern int > tipc_max_ports __read_mostly; extern int tipc_net_id __read_mostly; > extern int sysctl_tipc_rmem[3] __read_mostly; > +extern int sysctl_tipc_named_timeout __read_mostly; > > /* > * Other global variables > diff --git a/net/tipc/name_distr.c b/net/tipc/name_distr.c index > 0591f33..0cbe5e1 100644 > --- a/net/tipc/name_distr.c > +++ b/net/tipc/name_distr.c > @@ -1,7 +1,7 @@ > /* > * net/tipc/name_distr.c: TIPC name distribution code > * > - * Copyright (c) 2000-2006, Ericsson AB > + * Copyright (c) 2000-2006, 2014, Ericsson AB > * Copyright (c) 2005, 2010-2011, Wind River Systems > * All rights reserved. > * > @@ -71,6 +71,21 @@ static struct publ_list *publ_lists[] = { }; > > > +int sysctl_tipc_named_timeout __read_mostly = 2000; > + > +/** > + * struct tipc_dist_queue - queue holding deferred name table updates > +*/ static struct list_head tipc_dist_queue = > +LIST_HEAD_INIT(tipc_dist_queue); > + > +struct distr_queue_item { > + struct distr_item i; > + u32 dtype; > + u32 node; > + u64 expiry; > + struct list_head next; > +}; > + > /** > * publ_to_item - add publication info to a publication message > */ > @@ -299,6 +314,52 @@ struct publication *tipc_update_nametbl(struct > distr_item *i, u32 node, } > > /** > + * tipc_named_add_backlog - add a failed name table update to the > +backlog > + * > + */ > +static void tipc_named_add_backlog(struct distr_item *i, u32 type, u32 > +node) { > + struct distr_queue_item *e; > + u64 now = get_jiffies_64(); > + > + e = kzalloc(sizeof(*e), GFP_ATOMIC); > + if (!e) > + return; > + e->dtype = type; > + e->node = node; > + e->expiry = now + msecs_to_jiffies(sysctl_tipc_named_timeout); > + memcpy(e, i, sizeof(*i)); > + list_add_tail(&e->next, &tipc_dist_queue); } > + > +/** > + * tipc_named_process_backlog - try to process any pending name table > +updates > + * from the network. > + */ > +void tipc_named_process_backlog(void) > +{ > + struct distr_queue_item *e, *tmp; > + char addr[16]; > + u64 now = get_jiffies_64(); > + > + list_for_each_entry_safe(e, tmp, &tipc_dist_queue, next) { > + if (e->expiry > now) { > + if (!tipc_update_nametbl(&e->i, e->node, e- > >dtype)) > + continue; > + } else { > + tipc_addr_string_fill(addr, e->node); > + pr_warn_ratelimited("Dropping name table update > (%d) of {%u, %u, %u} from %s key=%u\n", > + e->dtype, ntohl(e->i.type), > + ntohl(e->i.lower), > + ntohl(e->i.upper), + tipc_addr_string_fill(addr), Otherwise you'll have a nice little crash here ;) Apart from this I am ok with it. You can add "Reviewed-by" from me. ///jon > + ntohl(e->i.key)); > + } > + list_del(&e->next); > + kfree(e); > + } > +} > + > +/** > * tipc_named_rcv - process name table update message sent by another > node > */ > void tipc_named_rcv(struct sk_buff *buf) @@ -306,13 +367,15 @@ void > tipc_named_rcv(struct sk_buff *buf) > struct tipc_msg *msg = buf_msg(buf); > struct distr_item *item = (struct distr_item *)msg_data(msg); > u32 count = msg_data_sz(msg) / ITEM_SIZE; > + u32 node = msg_orignode(msg); > > write_lock_bh(&tipc_nametbl_lock); > while (count--) { > - tipc_update_nametbl(item, msg_orignode(msg), > - msg_type(msg)); > + if (!tipc_update_nametbl(item, node, msg_type(msg))) > + tipc_named_add_backlog(item, msg_type(msg), > node); > item++; > } > + tipc_named_process_backlog(); > write_unlock_bh(&tipc_nametbl_lock); > kfree_skb(buf); > } > diff --git a/net/tipc/name_distr.h b/net/tipc/name_distr.h index > 8afe32b..b9e75fe 100644 > --- a/net/tipc/name_distr.h > +++ b/net/tipc/name_distr.h > @@ -73,5 +73,6 @@ void named_cluster_distribute(struct sk_buff *buf); > void tipc_named_node_up(u32 dnode); void tipc_named_rcv(struct sk_buff > *buf); void tipc_named_reinit(void); > +void tipc_named_process_backlog(void); > > #endif > diff --git a/net/tipc/name_table.c b/net/tipc/name_table.c index > c058e30..3a6a0a7 100644 > --- a/net/tipc/name_table.c > +++ b/net/tipc/name_table.c > @@ -261,8 +261,6 @@ static struct publication > *tipc_nameseq_insert_publ(struct name_seq *nseq, > > /* Lower end overlaps existing entry => need an exact match > */ > if ((sseq->lower != lower) || (sseq->upper != upper)) { > - pr_warn("Cannot publish {%u,%u,%u}, overlap > error\n", > - type, lower, upper); > return NULL; > } > > @@ -284,8 +282,6 @@ static struct publication > *tipc_nameseq_insert_publ(struct name_seq *nseq, > /* Fail if upper end overlaps into an existing entry */ > if ((inspos < nseq->first_free) && > (upper >= nseq->sseqs[inspos].lower)) { > - pr_warn("Cannot publish {%u,%u,%u}, overlap > error\n", > - type, lower, upper); > return NULL; > } > > @@ -677,6 +673,8 @@ struct publication *tipc_nametbl_publish(u32 type, > u32 lower, u32 upper, > if (likely(publ)) { > table.local_publ_count++; > buf = tipc_named_publish(publ); > + /* Any pending external events? */ > + tipc_named_process_backlog(); > } > write_unlock_bh(&tipc_nametbl_lock); > > @@ -698,6 +696,8 @@ int tipc_nametbl_withdraw(u32 type, u32 lower, u32 > ref, u32 key) > if (likely(publ)) { > table.local_publ_count--; > buf = tipc_named_withdraw(publ); > + /* Any pending external events? */ > + tipc_named_process_backlog(); > write_unlock_bh(&tipc_nametbl_lock); > list_del_init(&publ->pport_list); > kfree(publ); > diff --git a/net/tipc/sysctl.c b/net/tipc/sysctl.c index f3fef93..1a779b1 100644 > --- a/net/tipc/sysctl.c > +++ b/net/tipc/sysctl.c > @@ -47,6 +47,13 @@ static struct ctl_table tipc_table[] = { > .mode = 0644, > .proc_handler = proc_dointvec, > }, > + { > + .procname = "named_timeout", > + .data = &sysctl_tipc_named_timeout, > + .maxlen = > sizeof(sysctl_tipc_named_timeout), > + .mode = 0644, > + .proc_handler = proc_dointvec, > + }, > {} > }; > > -- > 1.8.3.2 -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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