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  1. 10 4月, 2016 4 次提交
    • M
      NFC: pn533: Separate physical layer from the core implementation · 9815c7cf
      由 Michael Thalmeier 提交于 
      The driver now has all core stuff isolated in one file, and all
the hardware link specifics in another. Writing a pn533 driver
on top of another hardware link is now just a matter of adding a
new file for that new hardware specifics.

The first user of this separation will be the i2c based pn532
driver that reuses pn533 core implementation on top of an i2c
layer.
Signed-off-by: NMichael Thalmeier <michael.thalmeier@hale.at>
Signed-off-by: NSamuel Ortiz <sameo@linux.intel.com>
      9815c7cf
    • M
      NFC: pn533: Fix socket deadlock · 37f895d7
      由 Michael Thalmeier 提交于 
      A deadlock can occur when the NFC raw socket is closed while
the driver is processing a command.

Following is the call graph of the affected situation:

send data via raw_sock:
-------------
rawsock_tx_work
  sock_hold => socket refcnt++
  nfc_data_exchange => cb = rawsock_data_exchange_complete

    ops->im_transceive = pn533_transceive => arg->cb = db
                               = rawsock_data_exchange_complete

      pn533_send_data_async => cb = pn533_data_exchange_complete

        __pn533_send_async => cmd->complete_cb = cb
                              = pn533_data_exchange_complete

          if_ops->send_frame_async

response:
--------
pn533_recv_response
  queue_work(priv->wq, &priv->cmd_complete_work)

pn533_wq_cmd_complete

  pn533_send_async_complete

    cmd->complete_cb() = pn533_data_exchange_complete()

      arg->cb() = rawsock_data_exchange_complete()

        sock_put => socket refcnt-- => If the corresponding
                    socket gets closed in the meantime socket
                    will be destructed

          sk_free

            __sk_free

              sk->sk_destruct = rawsock_destruct

                nfc_deactivate_target

                  ops->deactivate_target = pn533_deactivate_target

                    pn533_send_cmd_sync

                      pn533_send_cmd_async

                        __pn533_send_async

                          list_add_tail(&cmd->queue,&dev->cmd_queue)
                                  => add to command list because
                                     a command is currently
                                     processed

                        wait_for_completion
                                   => the workqueue thread waits
                                      here because it is the one
                                      processing the commands
                                         => deadlock

To fix the deadlock pn533_deactivate_target is changed to
issue the PN533_CMD_IN_RELEASE command in async mode. This
way nothing blocks and the release command is executed after
the current command.
Signed-off-by: NMichael Thalmeier <michael.thalmeier@hale.at>
Signed-off-by: NSamuel Ortiz <sameo@linux.intel.com>
      37f895d7
    • M
      NFC: pn533: Send ATR_REQ only if NFC_PROTO_NFC_DEP bit is set · e997ebbe
      由 Michael Thalmeier 提交于 
      Currently it is not possible to only poll for passive targets
with the pn533 driver. To change this ATR_REQ is only sent when
NFC_PROTO_NFC_DEP is explicitly requested in poll_protocols.
As most implementations (e.g. neard) poll for all protocols
that are reported to be supported by the adapter, this should
not have much of an effect on current implementations.
Signed-off-by: NMichael Thalmeier <michael.thalmeier@hale.at>
Signed-off-by: NSamuel Ortiz <sameo@linux.intel.com>
      e997ebbe
    • E
      ipv6: fix inet6_lookup_listener() · 03c5b534
      由 Eric Dumazet 提交于 
      A stupid refactoring bug in inet6_lookup_listener() needs to be fixed
in order to get proper SO_REUSEPORT behavior.

Fixes: 3b24d854 ("tcp/dccp: do not touch listener sk_refcnt under synflood")
Signed-off-by: NEric Dumazet <edumazet@google.com>
Reported-by: NMaciej Żenczykowski <maze@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      03c5b534
  3. 09 4月, 2016 33 次提交
  5. 08 4月, 2016 3 次提交
    • D
      Merge branch 'bpf-tracepoints' · f8711655
      由 David S. Miller 提交于 
      Alexei Starovoitov says:

====================
allow bpf attach to tracepoints

Hi Steven, Peter,

v1->v2: addressed Peter's comments:
- fixed wording in patch 1, added ack
- refactored 2nd patch into 3:
2/10 remove unused __perf_addr macro which frees up
an argument in perf_trace_buf_submit
3/10 split perf_trace_buf_prepare into alloc and update parts, so that bpf
programs don't have to pay performance penalty for update of struct trace_entry
which is not going to be accessed by bpf
4/10 actual addition of bpf filter to perf tracepoint handler is now trivial
and bpf prog can be used as proper filter of tracepoints

v1 cover:
last time we discussed bpf+tracepoints it was a year ago [1] and the reason
we didn't proceed with that approach was that bpf would make arguments
arg1, arg2 to trace_xx(arg1, arg2) call to be exposed to bpf program
and that was considered unnecessary extension of abi. Back then I wanted
to avoid the cost of buffer alloc and field assign part in all
of the tracepoints, but looks like when optimized the cost is acceptable.
So this new apporach doesn't expose any new abi to bpf program.
The program is looking at tracepoint fields after they were copied
by perf_trace_xx() and described in /sys/kernel/debug/tracing/events/xxx/format
We made a tool [2] that takes arguments from /sys/.../format and works as:
$ tplist.py -v random:urandom_read
    int got_bits;
    int pool_left;
    int input_left;
Then these fields can be copy-pasted into bpf program like:
struct urandom_read {
    __u64 hidden_pad;
    int got_bits;
    int pool_left;
    int input_left;
};
and the program can use it:
SEC("tracepoint/random/urandom_read")
int bpf_prog(struct urandom_read *ctx)
{
    return ctx->pool_left > 0 ? 1 : 0;
}
This way the program can access tracepoint fields faster than
equivalent bpf+kprobe program, which is the main goal of these patches.

Patch 1-4 are simple changes in perf core side, please review.
I'd like to take the whole set via net-next tree, since the rest of
the patches might conflict with other bpf work going on in net-next
and we want to avoid cross-tree merge conflicts.
Alternatively we can put patches 1-4 into both tip and net-next.

Patch 9 is an example of access to tracepoint fields from bpf prog.
Patch 10 is a micro benchmark for bpf+kprobe vs bpf+tracepoint.

Note that for actual tracing tools the user doesn't need to
run tplist.py and copy-paste fields manually. The tools do it
automatically. Like argdist tool [3] can be used as:
$ argdist -H 't:block:block_rq_complete():u32:nr_sector'
where 'nr_sector' is name of tracepoint field taken from
/sys/kernel/debug/tracing/events/block/block_rq_complete/format
and appropriate bpf program is generated on the fly.

[1] http://thread.gmane.org/gmane.linux.kernel.api/8127/focus=8165
[2] https://github.com/iovisor/bcc/blob/master/tools/tplist.py
[3] https://github.com/iovisor/bcc/blob/master/tools/argdist.py
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      f8711655
    • A
      samples/bpf: add tracepoint vs kprobe performance tests · e3edfdec
      由 Alexei Starovoitov 提交于 
      the first microbenchmark does
fd=open("/proc/self/comm");
for() {
  write(fd, "test");
}
and on 4 cpus in parallel:
                                      writes per sec
base (no tracepoints, no kprobes)         930k
with kprobe at __set_task_comm()          420k
with tracepoint at task:task_rename       730k

For kprobe + full bpf program manully fetches oldcomm, newcomm via bpf_probe_read.
For tracepint bpf program does nothing, since arguments are copied by tracepoint.

2nd microbenchmark does:
fd=open("/dev/urandom");
for() {
  read(fd, buf);
}
and on 4 cpus in parallel:
                                       reads per sec
base (no tracepoints, no kprobes)         300k
with kprobe at urandom_read()             279k
with tracepoint at random:urandom_read    290k

bpf progs attached to kprobe and tracepoint are noop.
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      e3edfdec
    • A
      samples/bpf: tracepoint example · 3c9b1644
      由 Alexei Starovoitov 提交于 
      modify offwaketime to work with sched/sched_switch tracepoint
instead of kprobe into finish_task_switch
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      3c9b1644