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Date: Mon, 29 Apr 2019 14:16:19 +0800
From: Xin Long <lucien.xin@...il.com>
To: network dev <netdev@...r.kernel.org>, linux-sctp@...r.kernel.org
Cc: davem@...emloft.net,
Marcelo Ricardo Leitner <marcelo.leitner@...il.com>,
Neil Horman <nhorman@...driver.com>
Subject: [PATCH net] sctp: avoid running the sctp state machine recursively
Ying triggered a call trace when doing an asconf testing:
BUG: scheduling while atomic: swapper/12/0/0x10000100
Call Trace:
<IRQ> [<ffffffffa4375904>] dump_stack+0x19/0x1b
[<ffffffffa436fcaf>] __schedule_bug+0x64/0x72
[<ffffffffa437b93a>] __schedule+0x9ba/0xa00
[<ffffffffa3cd5326>] __cond_resched+0x26/0x30
[<ffffffffa437bc4a>] _cond_resched+0x3a/0x50
[<ffffffffa3e22be8>] kmem_cache_alloc_node+0x38/0x200
[<ffffffffa423512d>] __alloc_skb+0x5d/0x2d0
[<ffffffffc0995320>] sctp_packet_transmit+0x610/0xa20 [sctp]
[<ffffffffc098510e>] sctp_outq_flush+0x2ce/0xc00 [sctp]
[<ffffffffc098646c>] sctp_outq_uncork+0x1c/0x20 [sctp]
[<ffffffffc0977338>] sctp_cmd_interpreter.isra.22+0xc8/0x1460 [sctp]
[<ffffffffc0976ad1>] sctp_do_sm+0xe1/0x350 [sctp]
[<ffffffffc099443d>] sctp_primitive_ASCONF+0x3d/0x50 [sctp]
[<ffffffffc0977384>] sctp_cmd_interpreter.isra.22+0x114/0x1460 [sctp]
[<ffffffffc0976ad1>] sctp_do_sm+0xe1/0x350 [sctp]
[<ffffffffc097b3a4>] sctp_assoc_bh_rcv+0xf4/0x1b0 [sctp]
[<ffffffffc09840f1>] sctp_inq_push+0x51/0x70 [sctp]
[<ffffffffc099732b>] sctp_rcv+0xa8b/0xbd0 [sctp]
As it shows, the first sctp_do_sm() running under atomic context (NET_RX
softirq) invoked sctp_primitive_ASCONF() that uses GFP_KERNEL flag later,
and this flag is supposed to be used in non-atomic context only. Besides,
sctp_do_sm() was called recursively, which is not expected.
Vlad tried to fix this recursive call in Commit c0786693404c ("sctp: Fix
oops when sending queued ASCONF chunks") by introducing a new command
SCTP_CMD_SEND_NEXT_ASCONF. But it didn't work as this command is still
used in the first sctp_do_sm() call, and sctp_primitive_ASCONF() will
be called in this command again.
To avoid calling sctp_do_sm() recursively, we send the next queued ASCONF
not by sctp_primitive_ASCONF(), but by sctp_sf_do_prm_asconf() in the 1st
sctp_do_sm() directly.
Reported-by: Ying Xu <yinxu@...hat.com>
Signed-off-by: Xin Long <lucien.xin@...il.com>
---
include/net/sctp/command.h | 1 -
net/sctp/sm_sideeffect.c | 29 -----------------------------
net/sctp/sm_statefuns.c | 35 +++++++++++++++++++++++++++--------
3 files changed, 27 insertions(+), 38 deletions(-)
diff --git a/include/net/sctp/command.h b/include/net/sctp/command.h
index 6640f84..6d5beac 100644
--- a/include/net/sctp/command.h
+++ b/include/net/sctp/command.h
@@ -105,7 +105,6 @@ enum sctp_verb {
SCTP_CMD_T1_RETRAN, /* Mark for retransmission after T1 timeout */
SCTP_CMD_UPDATE_INITTAG, /* Update peer inittag */
SCTP_CMD_SEND_MSG, /* Send the whole use message */
- SCTP_CMD_SEND_NEXT_ASCONF, /* Send the next ASCONF after ACK */
SCTP_CMD_PURGE_ASCONF_QUEUE, /* Purge all asconf queues.*/
SCTP_CMD_SET_ASOC, /* Restore association context */
SCTP_CMD_LAST
diff --git a/net/sctp/sm_sideeffect.c b/net/sctp/sm_sideeffect.c
index 1d143bc..4aa0358 100644
--- a/net/sctp/sm_sideeffect.c
+++ b/net/sctp/sm_sideeffect.c
@@ -1112,32 +1112,6 @@ static void sctp_cmd_send_msg(struct sctp_association *asoc,
}
-/* Sent the next ASCONF packet currently stored in the association.
- * This happens after the ASCONF_ACK was succeffully processed.
- */
-static void sctp_cmd_send_asconf(struct sctp_association *asoc)
-{
- struct net *net = sock_net(asoc->base.sk);
-
- /* Send the next asconf chunk from the addip chunk
- * queue.
- */
- if (!list_empty(&asoc->addip_chunk_list)) {
- struct list_head *entry = asoc->addip_chunk_list.next;
- struct sctp_chunk *asconf = list_entry(entry,
- struct sctp_chunk, list);
- list_del_init(entry);
-
- /* Hold the chunk until an ASCONF_ACK is received. */
- sctp_chunk_hold(asconf);
- if (sctp_primitive_ASCONF(net, asoc, asconf))
- sctp_chunk_free(asconf);
- else
- asoc->addip_last_asconf = asconf;
- }
-}
-
-
/* These three macros allow us to pull the debugging code out of the
* main flow of sctp_do_sm() to keep attention focused on the real
* functionality there.
@@ -1783,9 +1757,6 @@ static int sctp_cmd_interpreter(enum sctp_event_type event_type,
}
sctp_cmd_send_msg(asoc, cmd->obj.msg, gfp);
break;
- case SCTP_CMD_SEND_NEXT_ASCONF:
- sctp_cmd_send_asconf(asoc);
- break;
case SCTP_CMD_PURGE_ASCONF_QUEUE:
sctp_asconf_queue_teardown(asoc);
break;
diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c
index c9ae340..713a669 100644
--- a/net/sctp/sm_statefuns.c
+++ b/net/sctp/sm_statefuns.c
@@ -3824,6 +3824,29 @@ enum sctp_disposition sctp_sf_do_asconf(struct net *net,
return SCTP_DISPOSITION_CONSUME;
}
+static enum sctp_disposition sctp_send_next_asconf(
+ struct net *net,
+ const struct sctp_endpoint *ep,
+ struct sctp_association *asoc,
+ const union sctp_subtype type,
+ struct sctp_cmd_seq *commands)
+{
+ struct sctp_chunk *asconf;
+ struct list_head *entry;
+
+ if (list_empty(&asoc->addip_chunk_list))
+ return SCTP_DISPOSITION_CONSUME;
+
+ entry = asoc->addip_chunk_list.next;
+ asconf = list_entry(entry, struct sctp_chunk, list);
+
+ list_del_init(entry);
+ sctp_chunk_hold(asconf);
+ asoc->addip_last_asconf = asconf;
+
+ return sctp_sf_do_prm_asconf(net, ep, asoc, type, asconf, commands);
+}
+
/*
* ADDIP Section 4.3 General rules for address manipulation
* When building TLV parameters for the ASCONF Chunk that will add or
@@ -3915,14 +3938,10 @@ enum sctp_disposition sctp_sf_do_asconf_ack(struct net *net,
SCTP_TO(SCTP_EVENT_TIMEOUT_T4_RTO));
if (!sctp_process_asconf_ack((struct sctp_association *)asoc,
- asconf_ack)) {
- /* Successfully processed ASCONF_ACK. We can
- * release the next asconf if we have one.
- */
- sctp_add_cmd_sf(commands, SCTP_CMD_SEND_NEXT_ASCONF,
- SCTP_NULL());
- return SCTP_DISPOSITION_CONSUME;
- }
+ asconf_ack))
+ return sctp_send_next_asconf(net, ep,
+ (struct sctp_association *)asoc,
+ type, commands);
abort = sctp_make_abort(asoc, asconf_ack,
sizeof(struct sctp_errhdr));
--
2.1.0
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