linux-stable.git/net/dccp/timer.c, branch linux-4.9.y

dccp: fix tasklet usage

2018-05-19T08:26:57+00:00

[ Upstream commit a8d7aa17bbc970971ccdf71988ea19230ab368b1 ]

syzbot reported a crash in tasklet_action_common() caused by dccp.

dccp needs to make sure socket wont disappear before tasklet handler
has completed.

This patch takes a reference on the socket when arming the tasklet,
and moves the sock_put() from dccp_write_xmit_timer() to dccp_write_xmitlet()

kernel BUG at kernel/softirq.c:514!
invalid opcode: 0000 [#1] SMP KASAN
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 1 PID: 17 Comm: ksoftirqd/1 Not tainted 4.17.0-rc3+ #30
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:tasklet_action_common.isra.19+0x6db/0x700 kernel/softirq.c:515
RSP: 0018:ffff8801d9b3faf8 EFLAGS: 00010246
dccp_close: ABORT with 65423 bytes unread
RAX: 1ffff1003b367f6b RBX: ffff8801daf1f3f0 RCX: 0000000000000000
RDX: ffff8801cf895498 RSI: 0000000000000004 RDI: 0000000000000000
RBP: ffff8801d9b3fc40 R08: ffffed0039f12a95 R09: ffffed0039f12a94
dccp_close: ABORT with 65423 bytes unread
R10: ffffed0039f12a94 R11: ffff8801cf8954a3 R12: 0000000000000000
R13: ffff8801d9b3fc18 R14: dffffc0000000000 R15: ffff8801cf895490
FS:  0000000000000000(0000) GS:ffff8801daf00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2bc28000 CR3: 00000001a08a9000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 tasklet_action+0x1d/0x20 kernel/softirq.c:533
 __do_softirq+0x2e0/0xaf5 kernel/softirq.c:285
dccp_close: ABORT with 65423 bytes unread
 run_ksoftirqd+0x86/0x100 kernel/softirq.c:646
 smpboot_thread_fn+0x417/0x870 kernel/smpboot.c:164
 kthread+0x345/0x410 kernel/kthread.c:238
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412
Code: 48 8b 85 e8 fe ff ff 48 8b 95 f0 fe ff ff e9 94 fb ff ff 48 89 95 f0 fe ff ff e8 81 53 6e 00 48 8b 95 f0 fe ff ff e9 62 fb ff ff <0f> 0b 48 89 cf 48 89 8d e8 fe ff ff e8 64 53 6e 00 48 8b 8d e8
RIP: tasklet_action_common.isra.19+0x6db/0x700 kernel/softirq.c:515 RSP: ffff8801d9b3faf8

Fixes: dc841e30eaea ("dccp: Extend CCID packet dequeueing interface")
Signed-off-by: Eric Dumazet 
Reported-by: syzbot 
Cc: Gerrit Renker 
Cc: dccp@vger.kernel.org
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

net: rename NET_{ADD|INC}_STATS_BH()

2016-04-28T02:48:24+00:00

Rename NET_INC_STATS_BH() to __NET_INC_STATS()
and NET_ADD_STATS_BH() to __NET_ADD_STATS()

Signed-off-by: Eric Dumazet 
Signed-off-by: David S. Miller

dccp: rename DCCP_INC_STATS_BH()

2016-04-28T02:48:22+00:00

Rename DCCP_INC_STATS_BH() to __DCCP_INC_STATS()

Signed-off-by: Eric Dumazet 
Signed-off-by: David S. Miller

inet: get rid of central tcp/dccp listener timer

2015-03-20T16:40:25+00:00

One of the major issue for TCP is the SYNACK rtx handling,
done by inet_csk_reqsk_queue_prune(), fired by the keepalive
timer of a TCP_LISTEN socket.

This function runs for awful long times, with socket lock held,
meaning that other cpus needing this lock have to spin for hundred of ms.

SYNACK are sent in huge bursts, likely to cause severe drops anyway.

This model was OK 15 years ago when memory was very tight.

We now can afford to have a timer per request sock.

Timer invocations no longer need to lock the listener,
and can be run from all cpus in parallel.

With following patch increasing somaxconn width to 32 bits,
I tested a listener with more than 4 million active request sockets,
and a steady SYNFLOOD of ~200,000 SYN per second.
Host was sending ~830,000 SYNACK per second.

This is ~100 times more what we could achieve before this patch.

Later, we will get rid of the listener hash and use ehash instead.

Signed-off-by: Eric Dumazet 
Signed-off-by: David S. Miller

net/dccp/timer.c: use 'u64' instead of 's64' to avoid compiler's warning

2014-05-22T19:31:45+00:00

'dccp_timestamp_seed' is initialized once by ktime_get_real() in
dccp_timestamping_init(). It is always less than ktime_get_real()
in dccp_timestamp().

Then, ktime_us_delta() in dccp_timestamp() will always return positive
number. So can use manual type cast to let compiler and do_div() know
about it to avoid warning.

The related warning (with allmodconfig under unicore32):

    CC [M]  net/dccp/timer.o
  net/dccp/timer.c: In function ‘dccp_timestamp’:
  net/dccp/timer.c:285: warning: comparison of distinct pointer types lacks a cast

Signed-off-by: Chen Gang 
Signed-off-by: David S. Miller

net: Add export.h for EXPORT_SYMBOL/THIS_MODULE to non-modules

2011-10-31T23:30:30+00:00

These files are non modular, but need to export symbols using
the macros now living in export.h -- call out the include so
that things won't break when we remove the implicit presence
of module.h from everywhere.

Signed-off-by: Paul Gortmaker

dccp: Refine the wait-for-ccid mechanism

2010-10-28T17:27:01+00:00

This extends the existing wait-for-ccid routine so that it may be used with
different types of CCID, addressing the following problems:

 1) The queue-drain mechanism only works with rate-based CCIDs. If CCID-2 for
    example has a full TX queue and becomes network-limited just as the
    application wants to close, then waiting for CCID-2 to become unblocked
    could lead to an indefinite  delay (i.e., application "hangs").
 2) Since each TX CCID in turn uses a feedback mechanism, there may be changes
    in its sending policy while the queue is being drained. This can lead to
    further delays during which the application will not be able to terminate.
 3) The minimum wait time for CCID-3/4 can be expected to be the queue length
    times the current inter-packet delay. For example if tx_qlen=100 and a delay
    of 15 ms is used for each packet, then the application would have to wait
    for a minimum of 1.5 seconds before being allowed to exit.
 4) There is no way for the user/application to control this behaviour. It would
    be good to use the timeout argument of dccp_close() as an upper bound. Then
    the maximum time that an application is willing to wait for its CCIDs to can
    be set via the SO_LINGER option.

These problems are addressed by giving the CCID a grace period of up to the
`timeout' value.

The wait-for-ccid function is, as before, used when the application
 (a) has read all the data in its receive buffer and
 (b) if SO_LINGER was set with a non-zero linger time, or
 (c) the socket is either in the OPEN (active close) or in the PASSIVE_CLOSEREQ
     state (client application closes after receiving CloseReq).

In addition, there is a catch-all case of __skb_queue_purge() after waiting for
the CCID. This is necessary since the write queue may still have data when
 (a) the host has been passively-closed,
 (b) abnormal termination (unread data, zero linger time),
 (c) wait-for-ccid could not finish within the given time limit.

Signed-off-by: Gerrit Renker 
Signed-off-by: David S. Miller

dccp: Extend CCID packet dequeueing interface

2010-10-28T17:27:00+00:00

This extends the packet dequeuing interface of dccp_write_xmit() to allow
 1. CCIDs to take care of timing when the next packet may be sent;
 2. delayed sending (as before, with an inter-packet gap up to 65.535 seconds).

The main purpose is to take CCID-2 out of its polling mode (when it is network-
limited, it tries every millisecond to send, without interruption).

The mode of operation for (2) is as follows:
 * new packet is enqueued via dccp_sendmsg() => dccp_write_xmit(),
 * ccid_hc_tx_send_packet() detects that it may not send (e.g. window full),
 * it signals this condition via `CCID_PACKET_WILL_DEQUEUE_LATER',
 * dccp_write_xmit() returns without further action;
 * after some time the wait-condition for CCID becomes true,
 * that CCID schedules the tasklet,
 * tasklet function calls ccid_hc_tx_send_packet() via dccp_write_xmit(),
 * since the wait-condition is now true, ccid_hc_tx_packet() returns "send now",
 * packet is sent, and possibly more (since dccp_write_xmit() loops).

Code reuse: the taskled function calls dccp_write_xmit(), the timer function
            reduces to a wrapper around the same code.

Signed-off-by: Gerrit Renker 
Signed-off-by: David S. Miller

net: sk_dst_cache RCUification

2010-04-13T08:41:33+00:00

With latest CONFIG_PROVE_RCU stuff, I felt more comfortable to make this
work.

sk->sk_dst_cache is currently protected by a rwlock (sk_dst_lock)

This rwlock is readlocked for a very small amount of time, and dst
entries are already freed after RCU grace period. This calls for RCU
again :)

This patch converts sk_dst_lock to a spinlock, and use RCU for readers.

__sk_dst_get() is supposed to be called with rcu_read_lock() or if
socket locked by user, so use appropriate rcu_dereference_check()
condition (rcu_read_lock_held() || sock_owned_by_user(sk))

This patch avoids two atomic ops per tx packet on UDP connected sockets,
for example, and permits sk_dst_lock to be much less dirtied.

Signed-off-by: Eric Dumazet 
Signed-off-by: David S. Miller

net: Fix for dst_negative_advice

2009-10-21T01:55:46+00:00

dst_negative_advice() should check for changed dst and reset
sk_tx_queue_mapping accordingly. Pass sock to the callers of
dst_negative_advice.

(sk_reset_txq is defined just for use by dst_negative_advice. The
only way I could find to get around this is to move dst_negative_()
from dst.h to dst.c, include sock.h in dst.c, etc)

Signed-off-by: Krishna Kumar 
Signed-off-by: David S. Miller