xen/manage: fix potential deadlock when resuming the console

Calling xen_console_resume() in xen_suspend() causes a warning because
it locks irq_mapping_update_lock (a mutex) and this may sleep.  If a
userspace process is using the evtchn device then this mutex may be
locked at the point of the stop_machine() call and
xen_console_resume() would then deadlock.

Resuming the console after stop_machine() returns avoids this
deadlock.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: <stable@vger.kernel.org>
xen/balloon: set ballooned out pages as invalid in p2m

Since cd9151e26d31048b2b5e00fd02e110e07d2200c9 (xen/balloon: set a
mapping for ballooned out pages), a ballooned out page had its entry
in the p2m set to the MFN of one of the scratch pages.  This means
that the p2m will contain many entries pointing to the same MFN.

During a domain save, these many-to-one entries are not identified as
such and the scratch page is saved multiple times. On restore the
ballooned pages are populated with new frames and the domain may use
up its allocation before all pages can be restored.

Since the original fix only needed to keep a mapping for the ballooned
page it is safe to set ballooned out pages as INVALID_P2M_ENTRY in the
p2m (as they were before). Thus preventing them from being saved and
re-populated on restore.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Reported-by: Marek Marczykowski <marmarek@invisiblethingslab.com>
Tested-by: Marek Marczykowski <marmarek@invisiblethingslab.com>
Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: <stable@vger.kernel.org>
tracing: instance_rmdir() leaks ftrace_event_file->filter

instance_rmdir() path destroys the event files but forgets to free
file->filter. Change remove_event_file_dir() to free_event_filter().

Link: http://lkml.kernel.org/p/20140711190638.GA19517@redhat.com

Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Tom Zanussi <tom.zanussi@linux.intel.com>
Cc: "zhangwei(Jovi)" <jovi.zhangwei@huawei.com>
Cc: stable@vger.kernel.org # 3.11+
Fixes: f6a84bdc75b5 "tracing: Introduce remove_event_file_dir()"
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
tracing: Add ftrace_trace_stack into __trace_puts/__trace_bputs

Currently trace option stacktrace is not applicable for
trace_printk with constant string argument, the reason is
in __trace_puts/__trace_bputs ftrace_trace_stack is missing.

In contrast, when using trace_printk with non constant string
argument(will call into __trace_printk/__trace_bprintk), then
trace option stacktrace is workable, this inconstant result
will confuses users a lot.

Link: http://lkml.kernel.org/p/51E7A7C9.9040401@huawei.com

Cc: stable@vger.kernel.org # 3.10+
Signed-off-by: zhangwei(Jovi) <jovi.zhangwei@huawei.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
tracing: Fix graph tracer with stack tracer on other archs

Running my ftrace tests on PowerPC, it failed the test that checks
if function_graph tracer is affected by the stack tracer. It was.
Looking into this, I found that the update_function_graph_func()
must be called even if the trampoline function is not changed.
This is because archs like PowerPC do not support ftrace_ops being
passed by assembly and instead uses a helper function (what the
trampoline function points to). Since this function is not changed
even when multiple ftrace_ops are added to the code, the test that
falls out before calling update_function_graph_func() will miss that
the update must still be done.

Call update_function_graph_function() for all calls to
update_ftrace_function()

Cc: stable@vger.kernel.org # 3.3+
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
tracing: Add TRACE_ITER_PRINTK flag check in __trace_puts/__trace_bputs

The TRACE_ITER_PRINTK check in __trace_puts/__trace_bputs is missing,
so add it, to be consistent with __trace_printk/__trace_bprintk.
Those functions are all called by the same function: trace_printk().

Link: http://lkml.kernel.org/p/51E7A7D6.8090900@huawei.com

Cc: stable@vger.kernel.org # 3.11+
Signed-off-by: zhangwei(Jovi) <jovi.zhangwei@huawei.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
ring-buffer: Fix polling on trace_pipe

ring_buffer_poll_wait() should always put the poll_table to its wait_queue
even there is immediate data available.  Otherwise, the following epoll and
read sequence will eventually hang forever:

1. Put some data to make the trace_pipe ring_buffer read ready first
2. epoll_ctl(efd, EPOLL_CTL_ADD, trace_pipe_fd, ee)
3. epoll_wait()
4. read(trace_pipe_fd) till EAGAIN
5. Add some more data to the trace_pipe ring_buffer
6. epoll_wait() -> this epoll_wait() will block forever

~ During the epoll_ctl(efd, EPOLL_CTL_ADD,...) call in step 2,
  ring_buffer_poll_wait() returns immediately without adding poll_table,
  which has poll_table->_qproc pointing to ep_poll_callback(), to its
  wait_queue.
~ During the epoll_wait() call in step 3 and step 6,
  ring_buffer_poll_wait() cannot add ep_poll_callback() to its wait_queue
  because the poll_table->_qproc is NULL and it is how epoll works.
~ When there is new data available in step 6, ring_buffer does not know
  it has to call ep_poll_callback() because it is not in its wait queue.
  Hence, block forever.

Other poll implementation seems to call poll_wait() unconditionally as the very
first thing to do.  For example, tcp_poll() in tcp.c.

Link: http://lkml.kernel.org/p/20140610060637.GA14045@devbig242.prn2.facebook.com

Cc: stable@vger.kernel.org # 2.6.27
Fixes: 2a2cc8f7c4d0 "ftrace: allow the event pipe to be polled"
Reviewed-by: Chris Mason <clm@fb.com>
Signed-off-by: Martin Lau <kafai@fb.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Merge tag 'trace-fixes-v3.16-rc5-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing fixes from Steven Rostedt:
 "A few more fixes for ftrace infrastructure.

  I was cleaning out my INBOX and found two fixes from zhangwei from a
  year ago that were lost in my mail.  These fix an inconsistency
  between trace_puts() and the way trace_printk() works.  The reason
  this is important to fix is because when trace_printk() doesn't have
  any arguments, it turns into a trace_puts().  Not being able to enable
  a stack trace against trace_printk() because it does not have any
  arguments is quite confusing.  Also, the fix is rather trivial and low
  risk.

  While porting some changes to PowerPC I discovered that it still has
  the function graph tracer filter bug that if you also enable stack
  tracing the function graph tracer filter is ignored.  I fixed that up.

  Finally, Martin Lau, fixed a bug that would cause readers of the
  ftrace ring buffer to block forever even though it was suppose to be
  NONBLOCK"

This also includes the fix from an earlier pull request:

 "Oleg Nesterov fixed a memory leak that happens if a user creates a
  tracing instance, sets up a filter in an event, and then removes that
  instance.  The filter allocates memory that is never freed when the
  instance is destroyed"

* tag 'trace-fixes-v3.16-rc5-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  ring-buffer: Fix polling on trace_pipe
  tracing: Add TRACE_ITER_PRINTK flag check in __trace_puts/__trace_bputs
  tracing: Fix graph tracer with stack tracer on other archs
  tracing: Add ftrace_trace_stack into __trace_puts/__trace_bputs
  tracing: instance_rmdir() leaks ftrace_event_file->filter
Merge tag 'stable/for-linus-3.16-rc5-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip

Pull Xen fixes from Konrad Rzeszutek Wilk:
 "Two fixes found during migration of PV guests.  David would be the one
  doing this pull but he is on vacation.

  Fixes:
   - fix console deadlock when resuming PV guests
   - fix regression hit when ballooning and resuming PV guests"

* tag 'stable/for-linus-3.16-rc5-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  xen/balloon: set ballooned out pages as invalid in p2m
  xen/manage: fix potential deadlock when resuming the console