diff mbox

drm/i915: move i915_trace_irq_get() out of the tracing macro

Message ID 1371809753-16052-1-git-send-email-bigeasy@linutronix.de (mailing list archive)
State New, archived
Headers show

Commit Message

Sebastian Andrzej Siewior June 21, 2013, 10:15 a.m. UTC
There is a report on RT about "BUG: scheduling while atomic" because the
sleeping lock is taken in tracing context. This patch simply moves
locking operation out of the tracing macro.

Reported-by: Joakim Hernberg <jbh@alchemy.lu>
[C.Emde@osadl.org: pull out seqno and define it so it compiled]
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 drivers/gpu/drm/i915/i915_gem_execbuffer.c | 5 ++++-
 drivers/gpu/drm/i915/i915_trace.h          | 1 -
 drivers/gpu/drm/i915/intel_ringbuffer.h    | 2 ++
 3 files changed, 6 insertions(+), 2 deletions(-)

Comments

Sebastian Andrzej Siewior June 21, 2013, 12:51 p.m. UTC | #1
On 06/21/2013 01:08 PM, Chris Wilson wrote:
> On Fri, Jun 21, 2013 at 12:15:53PM +0200, Sebastian Andrzej Siewior wrote:
>> There is a report on RT about "BUG: scheduling while atomic" because the
>> sleeping lock is taken in tracing context. This patch simply moves
>> locking operation out of the tracing macro.
> 
> No. This enables the IRQ, as well as making a number of
> very expensively serialised read, unconditionally.

Ach in case CONFIG_TRACING is enabled but the tracepoint itself is
disabled. In that case it is probably best to drop this tracepoint from
-RT.

> -Chris
> 
Sebastian
Daniel Vetter June 24, 2013, 7:31 a.m. UTC | #2
On Fri, Jun 21, 2013 at 02:51:07PM +0200, Sebastian Andrzej Siewior wrote:
> On 06/21/2013 01:08 PM, Chris Wilson wrote:
> > On Fri, Jun 21, 2013 at 12:15:53PM +0200, Sebastian Andrzej Siewior wrote:
> >> There is a report on RT about "BUG: scheduling while atomic" because the
> >> sleeping lock is taken in tracing context. This patch simply moves
> >> locking operation out of the tracing macro.
> > 
> > No. This enables the IRQ, as well as making a number of
> > very expensively serialised read, unconditionally.
> 
> Ach in case CONFIG_TRACING is enabled but the tracepoint itself is
> disabled. In that case it is probably best to drop this tracepoint from
> -RT.

Iirc when we've last discussed this with Thomas Gleixner he mentioned that
there's a setup/teardown hook when enabling/disabling a tracepoint. We
could use that to enable/disable interrupts. Needs a notch of logic rework
though since the auto-irq disable code needs adjusting ... And on a 2nd
look that trace_irq_seqno logic looks a bit broken anyway.

It's somewhere on my todo list, but patches very much welcome.
-Daniel
diff mbox

Patch

diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index 87a3227..fa5b45f 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -844,6 +844,7 @@  i915_gem_do_execbuffer(struct drm_device *dev, void *data,
 	struct intel_ring_buffer *ring;
 	u32 ctx_id = i915_execbuffer2_get_context_id(*args);
 	u32 exec_start, exec_len;
+	u32 seqno;
 	u32 mask, flags;
 	int ret, mode, i;
 	bool need_relocs;
@@ -1081,7 +1082,9 @@  i915_gem_do_execbuffer(struct drm_device *dev, void *data,
 			goto err;
 	}
 
-	trace_i915_gem_ring_dispatch(ring, intel_ring_get_seqno(ring), flags);
+	seqno = intel_ring_get_seqno(ring);
+	trace_i915_gem_ring_dispatch(ring, seqno, flags);
+	i915_trace_irq_get(ring, seqno);
 
 	i915_gem_execbuffer_move_to_active(&eb->objects, ring);
 	i915_gem_execbuffer_retire_commands(dev, file, ring, batch_obj);
diff --git a/drivers/gpu/drm/i915/i915_trace.h b/drivers/gpu/drm/i915/i915_trace.h
index 3db4a68..29217db 100644
--- a/drivers/gpu/drm/i915/i915_trace.h
+++ b/drivers/gpu/drm/i915/i915_trace.h
@@ -244,7 +244,6 @@  TRACE_EVENT(i915_gem_ring_dispatch,
 			   __entry->ring = ring->id;
 			   __entry->seqno = seqno;
 			   __entry->flags = flags;
-			   i915_trace_irq_get(ring, seqno);
 			   ),
 
 	    TP_printk("dev=%u, ring=%u, seqno=%u, flags=%x",
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index 799f04c..13ffe58 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -262,8 +262,10 @@  static inline u32 intel_ring_get_seqno(struct intel_ring_buffer *ring)
 
 static inline void i915_trace_irq_get(struct intel_ring_buffer *ring, u32 seqno)
 {
+#ifdef CONFIG_TRACEPOINTS
 	if (ring->trace_irq_seqno == 0 && ring->irq_get(ring))
 		ring->trace_irq_seqno = seqno;
+#endif
 }
 
 /* DRI warts */