Merge remote branch 'intel/drm-intel-next' of /ssd/git/drm-next into drm-core-next

* 'intel/drm-intel-next' of /ssd/git/drm-next: (771 commits)
  drm/i915: Undo "Uncouple render/power ctx before suspending"
  drm/i915: Allow the application to choose the constant addressing mode
  drm/i915: dynamic render p-state support for Sandy Bridge
  drm/i915: Enable EI mode for RCx decision making on Sandybridge
  drm/i915/sdvo: Border and stall select became test bits in gen5
  drm/i915: Add Guess-o-matic for pageflip timestamping.
  drm/i915: Add support for precise vblank timestamping (v2)
  drm/i915: Add frame buffer compression on Sandybridge
  drm/i915: Add self-refresh support on Sandybridge
  drm/i915: Wait for vblank before unpinning old fb
  Revert "drm/i915: Avoid using PIPE_CONTROL on Ironlake"
  drm/i915: Pass clock limits down to PLL matcher
  drm/i915: Poll for seqno completion if IRQ is disabled
  drm/i915/ringbuffer: Make IRQ refcnting atomic
  agp/intel: Fix missed cached memory flags setting in i965_write_entry()
  drm/i915/sdvo: Only use the SDVO pin if it is in the valid range
  drm/i915: Enable RC6 autodownclocking on Sandybridge
  drm/i915: Terminate the FORCE WAKE after we have finished reading
  drm/i915/gtt: Clear the cachelines upon resume
  drm/i915: Restore GTT mapping first upon resume
  ...

1 files changed, 19 insertions, 0 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 042084157980..c380612273bf 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1283,6 +1283,8 @@ void trace_dump_stack(void)
         __ftrace_trace_stack(global_trace.buffer, flags, 3, preempt_count());
 }
 
+static DEFINE_PER_CPU(int, user_stack_count);
+
 void
 ftrace_trace_userstack(struct ring_buffer *buffer, unsigned long flags, int pc)
 {
@@ -1301,6 +1303,18 @@ ftrace_trace_userstack(struct ring_buffer *buffer, unsigned long flags, int pc)
         if (unlikely(in_nmi()))
                 return;
 
+        /*
+         * prevent recursion, since the user stack tracing may
+         * trigger other kernel events.
+         */
+        preempt_disable();
+        if (__this_cpu_read(user_stack_count))
+                goto out;
+
+        __this_cpu_inc(user_stack_count);
+
+
+
         event = trace_buffer_lock_reserve(buffer, TRACE_USER_STACK,
                                           sizeof(*entry), flags, pc);
         if (!event)
@@ -1318,6 +1332,11 @@ ftrace_trace_userstack(struct ring_buffer *buffer, unsigned long flags, int pc)
         save_stack_trace_user(&trace);
         if (!filter_check_discard(call, entry, buffer, event))
                 ring_buffer_unlock_commit(buffer, event);
+
+        __this_cpu_dec(user_stack_count);
+
+ out:
+        preempt_enable();
 }
 
 #ifdef UNUSED