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Message-Id: <20180821055018.431558270@linuxfoundation.org>
Date: Tue, 21 Aug 2018 08:20:48 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, kernel test robot <lkp@...el.com>,
David Howells <dhowells@...hat.com>,
"David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.17 16/42] rxrpc: Fix the keepalive generator [ver #2]
4.17-stable review patch. If anyone has any objections, please let me know.
------------------
From: David Howells <dhowells@...hat.com>
[ Upstream commit 330bdcfadceea5e9a1526d731711e163f9a90975 ]
AF_RXRPC has a keepalive message generator that generates a message for a
peer ~20s after the last transmission to that peer to keep firewall ports
open. The implementation is incorrect in the following ways:
(1) It mixes up ktime_t and time64_t types.
(2) It uses ktime_get_real(), the output of which may jump forward or
backward due to adjustments to the time of day.
(3) If the current time jumps forward too much or jumps backwards, the
generator function will crank the base of the time ring round one slot
at a time (ie. a 1s period) until it catches up, spewing out VERSION
packets as it goes.
Fix the problem by:
(1) Only using time64_t. There's no need for sub-second resolution.
(2) Use ktime_get_seconds() rather than ktime_get_real() so that time
isn't perceived to go backwards.
(3) Simplifying rxrpc_peer_keepalive_worker() by splitting it into two
parts:
(a) The "worker" function that manages the buckets and the timer.
(b) The "dispatch" function that takes the pending peers and
potentially transmits a keepalive packet before putting them back
in the ring into the slot appropriate to the revised last-Tx time.
(4) Taking everything that's pending out of the ring and splicing it into
a temporary collector list for processing.
In the case that there's been a significant jump forward, the ring
gets entirely emptied and then the time base can be warped forward
before the peers are processed.
The warping can't happen if the ring isn't empty because the slot a
peer is in is keepalive-time dependent, relative to the base time.
(5) Limit the number of iterations of the bucket array when scanning it.
(6) Set the timer to skip any empty slots as there's no point waking up if
there's nothing to do yet.
This can be triggered by an incoming call from a server after a reboot with
AF_RXRPC and AFS built into the kernel causing a peer record to be set up
before userspace is started. The system clock is then adjusted by
userspace, thereby potentially causing the keepalive generator to have a
meltdown - which leads to a message like:
watchdog: BUG: soft lockup - CPU#0 stuck for 23s! [kworker/0:1:23]
...
Workqueue: krxrpcd rxrpc_peer_keepalive_worker
EIP: lock_acquire+0x69/0x80
...
Call Trace:
? rxrpc_peer_keepalive_worker+0x5e/0x350
? _raw_spin_lock_bh+0x29/0x60
? rxrpc_peer_keepalive_worker+0x5e/0x350
? rxrpc_peer_keepalive_worker+0x5e/0x350
? __lock_acquire+0x3d3/0x870
? process_one_work+0x110/0x340
? process_one_work+0x166/0x340
? process_one_work+0x110/0x340
? worker_thread+0x39/0x3c0
? kthread+0xdb/0x110
? cancel_delayed_work+0x90/0x90
? kthread_stop+0x70/0x70
? ret_from_fork+0x19/0x24
Fixes: ace45bec6d77 ("rxrpc: Fix firewall route keepalive")
Reported-by: kernel test robot <lkp@...el.com>
Signed-off-by: David Howells <dhowells@...hat.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
net/rxrpc/ar-internal.h | 8 +-
net/rxrpc/conn_event.c | 4 -
net/rxrpc/net_ns.c | 6 -
net/rxrpc/output.c | 12 +--
net/rxrpc/peer_event.c | 162 ++++++++++++++++++++++++++----------------------
net/rxrpc/peer_object.c | 8 +-
net/rxrpc/rxkad.c | 4 -
7 files changed, 112 insertions(+), 92 deletions(-)
--- a/net/rxrpc/ar-internal.h
+++ b/net/rxrpc/ar-internal.h
@@ -104,9 +104,9 @@ struct rxrpc_net {
#define RXRPC_KEEPALIVE_TIME 20 /* NAT keepalive time in seconds */
u8 peer_keepalive_cursor;
- ktime_t peer_keepalive_base;
- struct hlist_head peer_keepalive[RXRPC_KEEPALIVE_TIME + 1];
- struct hlist_head peer_keepalive_new;
+ time64_t peer_keepalive_base;
+ struct list_head peer_keepalive[32];
+ struct list_head peer_keepalive_new;
struct timer_list peer_keepalive_timer;
struct work_struct peer_keepalive_work;
};
@@ -295,7 +295,7 @@ struct rxrpc_peer {
struct hlist_head error_targets; /* targets for net error distribution */
struct work_struct error_distributor;
struct rb_root service_conns; /* Service connections */
- struct hlist_node keepalive_link; /* Link in net->peer_keepalive[] */
+ struct list_head keepalive_link; /* Link in net->peer_keepalive[] */
time64_t last_tx_at; /* Last time packet sent here */
seqlock_t service_conn_lock;
spinlock_t lock; /* access lock */
--- a/net/rxrpc/conn_event.c
+++ b/net/rxrpc/conn_event.c
@@ -136,7 +136,7 @@ static void rxrpc_conn_retransmit_call(s
}
ret = kernel_sendmsg(conn->params.local->socket, &msg, iov, ioc, len);
- conn->params.peer->last_tx_at = ktime_get_real();
+ conn->params.peer->last_tx_at = ktime_get_seconds();
if (ret < 0)
trace_rxrpc_tx_fail(conn->debug_id, serial, ret,
rxrpc_tx_fail_call_final_resend);
@@ -245,7 +245,7 @@ static int rxrpc_abort_connection(struct
return -EAGAIN;
}
- conn->params.peer->last_tx_at = ktime_get_real();
+ conn->params.peer->last_tx_at = ktime_get_seconds();
_leave(" = 0");
return 0;
--- a/net/rxrpc/net_ns.c
+++ b/net/rxrpc/net_ns.c
@@ -85,12 +85,12 @@ static __net_init int rxrpc_init_net(str
hash_init(rxnet->peer_hash);
spin_lock_init(&rxnet->peer_hash_lock);
for (i = 0; i < ARRAY_SIZE(rxnet->peer_keepalive); i++)
- INIT_HLIST_HEAD(&rxnet->peer_keepalive[i]);
- INIT_HLIST_HEAD(&rxnet->peer_keepalive_new);
+ INIT_LIST_HEAD(&rxnet->peer_keepalive[i]);
+ INIT_LIST_HEAD(&rxnet->peer_keepalive_new);
timer_setup(&rxnet->peer_keepalive_timer,
rxrpc_peer_keepalive_timeout, 0);
INIT_WORK(&rxnet->peer_keepalive_work, rxrpc_peer_keepalive_worker);
- rxnet->peer_keepalive_base = ktime_add(ktime_get_real(), NSEC_PER_SEC);
+ rxnet->peer_keepalive_base = ktime_get_seconds();
ret = -ENOMEM;
rxnet->proc_net = proc_net_mkdir(net, "rxrpc", net->proc_net);
--- a/net/rxrpc/output.c
+++ b/net/rxrpc/output.c
@@ -209,7 +209,7 @@ int rxrpc_send_ack_packet(struct rxrpc_c
now = ktime_get_real();
if (ping)
call->ping_time = now;
- conn->params.peer->last_tx_at = ktime_get_real();
+ conn->params.peer->last_tx_at = ktime_get_seconds();
if (ret < 0)
trace_rxrpc_tx_fail(call->debug_id, serial, ret,
rxrpc_tx_fail_call_ack);
@@ -296,7 +296,7 @@ int rxrpc_send_abort_packet(struct rxrpc
ret = kernel_sendmsg(conn->params.local->socket,
&msg, iov, 1, sizeof(pkt));
- conn->params.peer->last_tx_at = ktime_get_real();
+ conn->params.peer->last_tx_at = ktime_get_seconds();
if (ret < 0)
trace_rxrpc_tx_fail(call->debug_id, serial, ret,
rxrpc_tx_fail_call_abort);
@@ -391,7 +391,7 @@ int rxrpc_send_data_packet(struct rxrpc_
* message and update the peer record
*/
ret = kernel_sendmsg(conn->params.local->socket, &msg, iov, 2, len);
- conn->params.peer->last_tx_at = ktime_get_real();
+ conn->params.peer->last_tx_at = ktime_get_seconds();
up_read(&conn->params.local->defrag_sem);
if (ret < 0)
@@ -457,7 +457,7 @@ send_fragmentable:
if (ret == 0) {
ret = kernel_sendmsg(conn->params.local->socket, &msg,
iov, 2, len);
- conn->params.peer->last_tx_at = ktime_get_real();
+ conn->params.peer->last_tx_at = ktime_get_seconds();
opt = IP_PMTUDISC_DO;
kernel_setsockopt(conn->params.local->socket, SOL_IP,
@@ -475,7 +475,7 @@ send_fragmentable:
if (ret == 0) {
ret = kernel_sendmsg(conn->params.local->socket, &msg,
iov, 2, len);
- conn->params.peer->last_tx_at = ktime_get_real();
+ conn->params.peer->last_tx_at = ktime_get_seconds();
opt = IPV6_PMTUDISC_DO;
kernel_setsockopt(conn->params.local->socket,
@@ -599,6 +599,6 @@ void rxrpc_send_keepalive(struct rxrpc_p
trace_rxrpc_tx_fail(peer->debug_id, 0, ret,
rxrpc_tx_fail_version_keepalive);
- peer->last_tx_at = ktime_get_real();
+ peer->last_tx_at = ktime_get_seconds();
_leave("");
}
--- a/net/rxrpc/peer_event.c
+++ b/net/rxrpc/peer_event.c
@@ -350,97 +350,117 @@ void rxrpc_peer_add_rtt(struct rxrpc_cal
}
/*
- * Perform keep-alive pings with VERSION packets to keep any NAT alive.
+ * Perform keep-alive pings.
*/
-void rxrpc_peer_keepalive_worker(struct work_struct *work)
+static void rxrpc_peer_keepalive_dispatch(struct rxrpc_net *rxnet,
+ struct list_head *collector,
+ time64_t base,
+ u8 cursor)
{
- struct rxrpc_net *rxnet =
- container_of(work, struct rxrpc_net, peer_keepalive_work);
struct rxrpc_peer *peer;
- unsigned long delay;
- ktime_t base, now = ktime_get_real();
- s64 diff;
- u8 cursor, slot;
+ const u8 mask = ARRAY_SIZE(rxnet->peer_keepalive) - 1;
+ time64_t keepalive_at;
+ int slot;
- base = rxnet->peer_keepalive_base;
- cursor = rxnet->peer_keepalive_cursor;
-
- _enter("%u,%lld", cursor, ktime_sub(now, base));
+ spin_lock_bh(&rxnet->peer_hash_lock);
-next_bucket:
- diff = ktime_to_ns(ktime_sub(now, base));
- if (diff < 0)
- goto resched;
+ while (!list_empty(collector)) {
+ peer = list_entry(collector->next,
+ struct rxrpc_peer, keepalive_link);
+
+ list_del_init(&peer->keepalive_link);
+ if (!rxrpc_get_peer_maybe(peer))
+ continue;
- _debug("at %u", cursor);
- spin_lock_bh(&rxnet->peer_hash_lock);
-next_peer:
- if (!rxnet->live) {
spin_unlock_bh(&rxnet->peer_hash_lock);
- goto out;
- }
- /* Everything in the bucket at the cursor is processed this second; the
- * bucket at cursor + 1 goes now + 1s and so on...
- */
- if (hlist_empty(&rxnet->peer_keepalive[cursor])) {
- if (hlist_empty(&rxnet->peer_keepalive_new)) {
- spin_unlock_bh(&rxnet->peer_hash_lock);
- goto emptied_bucket;
+ keepalive_at = peer->last_tx_at + RXRPC_KEEPALIVE_TIME;
+ slot = keepalive_at - base;
+ _debug("%02x peer %u t=%d {%pISp}",
+ cursor, peer->debug_id, slot, &peer->srx.transport);
+
+ if (keepalive_at <= base ||
+ keepalive_at > base + RXRPC_KEEPALIVE_TIME) {
+ rxrpc_send_keepalive(peer);
+ slot = RXRPC_KEEPALIVE_TIME;
}
- hlist_move_list(&rxnet->peer_keepalive_new,
- &rxnet->peer_keepalive[cursor]);
+ /* A transmission to this peer occurred since last we examined
+ * it so put it into the appropriate future bucket.
+ */
+ slot += cursor;
+ slot &= mask;
+ spin_lock_bh(&rxnet->peer_hash_lock);
+ list_add_tail(&peer->keepalive_link,
+ &rxnet->peer_keepalive[slot & mask]);
+ rxrpc_put_peer(peer);
}
- peer = hlist_entry(rxnet->peer_keepalive[cursor].first,
- struct rxrpc_peer, keepalive_link);
- hlist_del_init(&peer->keepalive_link);
- if (!rxrpc_get_peer_maybe(peer))
- goto next_peer;
-
spin_unlock_bh(&rxnet->peer_hash_lock);
+}
+
+/*
+ * Perform keep-alive pings with VERSION packets to keep any NAT alive.
+ */
+void rxrpc_peer_keepalive_worker(struct work_struct *work)
+{
+ struct rxrpc_net *rxnet =
+ container_of(work, struct rxrpc_net, peer_keepalive_work);
+ const u8 mask = ARRAY_SIZE(rxnet->peer_keepalive) - 1;
+ time64_t base, now, delay;
+ u8 cursor, stop;
+ LIST_HEAD(collector);
- _debug("peer %u {%pISp}", peer->debug_id, &peer->srx.transport);
+ now = ktime_get_seconds();
+ base = rxnet->peer_keepalive_base;
+ cursor = rxnet->peer_keepalive_cursor;
+ _enter("%lld,%u", base - now, cursor);
-recalc:
- diff = ktime_divns(ktime_sub(peer->last_tx_at, base), NSEC_PER_SEC);
- if (diff < -30 || diff > 30)
- goto send; /* LSW of 64-bit time probably wrapped on 32-bit */
- diff += RXRPC_KEEPALIVE_TIME - 1;
- if (diff < 0)
- goto send;
-
- slot = (diff > RXRPC_KEEPALIVE_TIME - 1) ? RXRPC_KEEPALIVE_TIME - 1 : diff;
- if (slot == 0)
- goto send;
+ if (!rxnet->live)
+ return;
- /* A transmission to this peer occurred since last we examined it so
- * put it into the appropriate future bucket.
+ /* Remove to a temporary list all the peers that are currently lodged
+ * in expired buckets plus all new peers.
+ *
+ * Everything in the bucket at the cursor is processed this
+ * second; the bucket at cursor + 1 goes at now + 1s and so
+ * on...
*/
- slot = (slot + cursor) % ARRAY_SIZE(rxnet->peer_keepalive);
spin_lock_bh(&rxnet->peer_hash_lock);
- hlist_add_head(&peer->keepalive_link, &rxnet->peer_keepalive[slot]);
- rxrpc_put_peer(peer);
- goto next_peer;
-
-send:
- rxrpc_send_keepalive(peer);
- now = ktime_get_real();
- goto recalc;
-
-emptied_bucket:
- cursor++;
- if (cursor >= ARRAY_SIZE(rxnet->peer_keepalive))
- cursor = 0;
- base = ktime_add_ns(base, NSEC_PER_SEC);
- goto next_bucket;
+ list_splice_init(&rxnet->peer_keepalive_new, &collector);
+
+ stop = cursor + ARRAY_SIZE(rxnet->peer_keepalive);
+ while (base <= now && (s8)(cursor - stop) < 0) {
+ list_splice_tail_init(&rxnet->peer_keepalive[cursor & mask],
+ &collector);
+ base++;
+ cursor++;
+ }
+
+ base = now;
+ spin_unlock_bh(&rxnet->peer_hash_lock);
-resched:
rxnet->peer_keepalive_base = base;
rxnet->peer_keepalive_cursor = cursor;
- delay = nsecs_to_jiffies(-diff) + 1;
- timer_reduce(&rxnet->peer_keepalive_timer, jiffies + delay);
-out:
+ rxrpc_peer_keepalive_dispatch(rxnet, &collector, base, cursor);
+ ASSERT(list_empty(&collector));
+
+ /* Schedule the timer for the next occupied timeslot. */
+ cursor = rxnet->peer_keepalive_cursor;
+ stop = cursor + RXRPC_KEEPALIVE_TIME - 1;
+ for (; (s8)(cursor - stop) < 0; cursor++) {
+ if (!list_empty(&rxnet->peer_keepalive[cursor & mask]))
+ break;
+ base++;
+ }
+
+ now = ktime_get_seconds();
+ delay = base - now;
+ if (delay < 1)
+ delay = 1;
+ delay *= HZ;
+ if (rxnet->live)
+ timer_reduce(&rxnet->peer_keepalive_timer, jiffies + delay);
+
_leave("");
}
--- a/net/rxrpc/peer_object.c
+++ b/net/rxrpc/peer_object.c
@@ -322,7 +322,7 @@ struct rxrpc_peer *rxrpc_lookup_incoming
if (!peer) {
peer = prealloc;
hash_add_rcu(rxnet->peer_hash, &peer->hash_link, hash_key);
- hlist_add_head(&peer->keepalive_link, &rxnet->peer_keepalive_new);
+ list_add_tail(&peer->keepalive_link, &rxnet->peer_keepalive_new);
}
spin_unlock(&rxnet->peer_hash_lock);
@@ -367,8 +367,8 @@ struct rxrpc_peer *rxrpc_lookup_peer(str
if (!peer) {
hash_add_rcu(rxnet->peer_hash,
&candidate->hash_link, hash_key);
- hlist_add_head(&candidate->keepalive_link,
- &rxnet->peer_keepalive_new);
+ list_add_tail(&candidate->keepalive_link,
+ &rxnet->peer_keepalive_new);
}
spin_unlock_bh(&rxnet->peer_hash_lock);
@@ -441,7 +441,7 @@ static void __rxrpc_put_peer(struct rxrp
spin_lock_bh(&rxnet->peer_hash_lock);
hash_del_rcu(&peer->hash_link);
- hlist_del_init(&peer->keepalive_link);
+ list_del_init(&peer->keepalive_link);
spin_unlock_bh(&rxnet->peer_hash_lock);
kfree_rcu(peer, rcu);
--- a/net/rxrpc/rxkad.c
+++ b/net/rxrpc/rxkad.c
@@ -669,7 +669,7 @@ static int rxkad_issue_challenge(struct
return -EAGAIN;
}
- conn->params.peer->last_tx_at = ktime_get_real();
+ conn->params.peer->last_tx_at = ktime_get_seconds();
_leave(" = 0");
return 0;
}
@@ -725,7 +725,7 @@ static int rxkad_send_response(struct rx
return -EAGAIN;
}
- conn->params.peer->last_tx_at = ktime_get_real();
+ conn->params.peer->last_tx_at = ktime_get_seconds();
_leave(" = 0");
return 0;
}
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