linux-toradex.git/net/sunrpc/xprtsock.c, branch v4.9.76

sunrpc: fix some missing rq_rbuffer assignments

2016-10-28T20:57:33+00:00

We've been seeing some crashes in testing that look like this:

BUG: unable to handle kernel NULL pointer dereference at           (null)
IP: [] memcpy_orig+0x29/0x110
PGD 212ca2067 PUD 212ca3067 PMD 0
Oops: 0002 [#1] SMP
Modules linked in: rpcsec_gss_krb5 nfsv4 dns_resolver nfs fscache ppdev parport_pc i2c_piix4 sg parport i2c_core virtio_balloon pcspkr acpi_cpufreq nfsd auth_rpcgss nfs_acl lockd grace sunrpc ip_tables xfs libcrc32c sd_mod ata_generic pata_acpi virtio_scsi 8139too ata_piix libata 8139cp mii virtio_pci floppy virtio_ring serio_raw virtio
CPU: 1 PID: 1540 Comm: nfsd Not tainted 4.9.0-rc1 #39
Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2007
task: ffff88020d7ed200 task.stack: ffff880211838000
RIP: 0010:[]  [] memcpy_orig+0x29/0x110
RSP: 0018:ffff88021183bdd0  EFLAGS: 00010206
RAX: 0000000000000000 RBX: ffff88020d7fa000 RCX: 000000f400000000
RDX: 0000000000000014 RSI: ffff880212927020 RDI: 0000000000000000
RBP: ffff88021183be30 R08: 01000000ef896996 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff880211704ca8
R13: ffff88021473f000 R14: 00000000ef896996 R15: ffff880211704800
FS:  0000000000000000(0000) GS:ffff88021fc80000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000212ca1000 CR4: 00000000000006e0
Stack:
 ffffffffa01ea087 ffffffff63400001 ffff880215145e00 ffff880211bacd00
 ffff88021473f2b8 0000000000000004 00000000d0679d67 ffff880211bacd00
 ffff88020d7fa000 ffff88021473f000 0000000000000000 ffff88020d7faa30
Call Trace:
 [] ? svc_tcp_recvfrom+0x5a7/0x790 [sunrpc]
 [] svc_recv+0xad8/0xbd0 [sunrpc]
 [] nfsd+0xde/0x160 [nfsd]
 [] ? nfsd_destroy+0x60/0x60 [nfsd]
 [] kthread+0xd8/0xf0
 [] ret_from_fork+0x1f/0x40
 [] ? kthread_park+0x60/0x60
Code: 00 00 48 89 f8 48 83 fa 20 72 7e 40 38 fe 7c 35 48 83 ea 20 48 83 ea 20 4c 8b 06 4c 8b 4e 08 4c 8b 56 10 4c 8b 5e 18 48 8d 76 20 <4c> 89 07 4c 89 4f 08 4c 89 57 10 4c 89 5f 18 48 8d 7f 20 73 d4
RIP  [] memcpy_orig+0x29/0x110
 RSP 
CR2: 0000000000000000

Both Bruce and Eryu ran a bisect here and found that the problematic
patch was 68778945e46 (SUNRPC: Separate buffer pointers for RPC Call and
Reply messages).

That patch changed rpc_xdr_encode to use a new rq_rbuffer pointer to
set up the receive buffer, but didn't change all of the necessary
codepaths to set it properly. In particular the backchannel setup was
missing.

We need to set rq_rbuffer whenever rq_buffer is set. Ensure that it is.

Reviewed-by: Chuck Lever 
Tested-by: Chuck Lever 
Reported-by: Eryu Guan 
Tested-by: Eryu Guan 
Fixes: 68778945e46 "SUNRPC: Separate buffer pointers..."
Reported-by: J. Bruce Fields 
Signed-off-by: Jeff Layton 
Signed-off-by: J. Bruce Fields

sunrpc: fix write space race causing stalls

2016-09-19T17:21:36+00:00

Write space becoming available may race with putting the task to sleep
in xprt_wait_for_buffer_space().  The existing mechanism to avoid the
race does not work.

This (edited) partial trace illustrates the problem:

   [1] rpc_task_run_action: task:43546@5 ... action=call_transmit
   [2] xs_write_space <-xs_tcp_write_space
   [3] xprt_write_space <-xs_write_space
   [4] rpc_task_sleep: task:43546@5 ...
   [5] xs_write_space <-xs_tcp_write_space

[1] Task 43546 runs but is out of write space.

[2] Space becomes available, xs_write_space() clears the
    SOCKWQ_ASYNC_NOSPACE bit.

[3] xprt_write_space() attemts to wake xprt->snd_task (== 43546), but
    this has not yet been queued and the wake up is lost.

[4] xs_nospace() is called which calls xprt_wait_for_buffer_space()
    which queues task 43546.

[5] The call to sk->sk_write_space() at the end of xs_nospace() (which
    is supposed to handle the above race) does not call
    xprt_write_space() as the SOCKWQ_ASYNC_NOSPACE bit is clear and
    thus the task is not woken.

Fix the race by resetting the SOCKWQ_ASYNC_NOSPACE bit in xs_nospace()
so the second call to sk->sk_write_space() calls xprt_write_space().

Suggested-by: Trond Myklebust 
Signed-off-by: David Vrabel 
cc: stable@vger.kernel.org # 4.4
Signed-off-by: Anna Schumaker

SUNRPC: Generalize the RPC buffer release API

2016-09-19T17:08:37+00:00

xprtrdma needs to allocate the Call and Reply buffers separately.
TBH, the reliance on using a single buffer for the pair of XDR
buffers is transport implementation-specific.

Instead of passing just the rq_buffer into the buf_free method, pass
the task structure and let buf_free take care of freeing both
XDR buffers at once.

There's a micro-optimization here. In the common case, both
xprt_release and the transport's buf_free method were checking if
rq_buffer was NULL. Now the check is done only once per RPC.

Signed-off-by: Chuck Lever 
Signed-off-by: Anna Schumaker

SUNRPC: Generalize the RPC buffer allocation API

2016-09-19T17:08:37+00:00

xprtrdma needs to allocate the Call and Reply buffers separately.
TBH, the reliance on using a single buffer for the pair of XDR
buffers is transport implementation-specific.

Transports that want to allocate separate Call and Reply buffers
will ignore the "size" argument anyway.  Don't bother passing it.

The buf_alloc method can't return two pointers. Instead, make the
method's return value an error code, and set the rq_buffer pointer
in the method itself.

This gives call_allocate an opportunity to terminate an RPC instead
of looping forever when a permanent problem occurs. If a request is
just bogus, or the transport is in a state where it can't allocate
resources for any request, there needs to be a way to kill the RPC
right there and not loop.

This immediately fixes a rare problem in the backchannel send path,
which loops if the server happens to send a CB request whose
call+reply size is larger than a page (which it shouldn't do yet).

One more issue: looks like xprt_inject_disconnect was incorrectly
placed in the failure path in call_allocate. It needs to be in the
success path, as it is for other call-sites.

Signed-off-by: Chuck Lever 
Signed-off-by: Anna Schumaker

sunrpc: fix UDP memory accounting

2016-09-03T14:00:49+00:00

The commit f9b2ee714c5c ("SUNRPC: Move UDP receive data path
into a workqueue context"), as a side effect, moved the
skb_free_datagram() call outside the scope of the related socket
lock, but UDP sockets require such lock to be held for proper
memory accounting.
Fix it by replacing skb_free_datagram() with
skb_free_datagram_locked().

Fixes: f9b2ee714c5c ("SUNRPC: Move UDP receive data path into a workqueue context")
Reported-and-tested-by: Jan Stancek 
Signed-off-by: Paolo Abeni 
Cc: stable@vger.kernel.org # 4.4+
Signed-off-by: Trond Myklebust

SUNRPC: Limit the reconnect backoff timer to the max RPC message timeout

2016-08-05T18:12:09+00:00

...and ensure that we propagate it to new transports on the same
client.

Signed-off-by: Trond Myklebust

SUNRPC: Fix reconnection timeouts

2016-08-05T16:18:10+00:00

When the connect attempt fails and backs off, we should start the clock
at the last connection attempt, not time at which we queue up the
reconnect job.

Signed-off-by: Trond Myklebust

SUNRPC: disable the use of IPv6 temporary addresses.

2016-08-05T15:29:59+00:00

If the net.ipv6.conf.*.use_temp_addr sysctl is set to '2',
then TCP connections over IPv6 will prefer a 'private' source
address.
These eventually expire and become invalid, typically after a week,
but the time is configurable.

When the local address becomes invalid the client will not be able to
receive replies from the server.  Eventually the connection will timeout
or break and a new connection will be established, but this can take
half an hour (typically TCP connection break time).

RFC 4941, which describes private IPv6 addresses, acknowledges that some
applications might not work well with them and that the application may
explicitly a request non-temporary (i.e. "public") address.

I believe this is correct for SUNRPC clients.  Without this change, a
client will occasionally experience a long delay if private addresses
have been enabled.

The privacy offered by private addresses is of little value for an NFS
server which requires client authentication.

For NFSv3 this will often not be a problem because idle connections are
closed after 5 minutes.  For NFSv4 connections never go idle due to the
period RENEW (or equivalent) request.

Signed-off-by: NeilBrown 
Signed-off-by: Trond Myklebust

SUNRPC: Handle EADDRNOTAVAIL on connection failures

2016-08-01T19:03:02+00:00

If the connect attempt immediately fails with an EADDRNOTAVAIL error, then
that means our choice of source port number was bad.
This error is expected when we set the SO_REUSEPORT socket option and we
have 2 sockets sharing the same source and destination address and port
combinations.

Signed-off-by: Trond Myklebust 
Fixes: 402e23b4ed9ed ("SUNRPC: Fix stupid typo in xs_sock_set_reuseport")
Cc: stable@vger.kernel.org # v4.0+

Merge branch 'sunrpc'

2016-07-24T21:08:31+00:00