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* [PATCH] drm/i915: Copy name string into ring buffer for intel_update/disable_plane tracepoints
@ 2019-07-10 16:01 Steven Rostedt
  2019-07-10 16:44 ` ✗ Fi.CI.BAT: failure for " Patchwork
                   ` (3 more replies)
  0 siblings, 4 replies; 6+ messages in thread
From: Steven Rostedt @ 2019-07-10 16:01 UTC (permalink / raw)
  To: intel-gfx, dri-devel, LKML
  Cc: Ville Syrjälä, Maarten Lankhorst, David Airlie, Daniel Vetter


From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>

Currently the intel_update_plane and intel_disable_plane tracepoints record
the address of plane->name in the ring buffer, and then when reading the
ring buffer uses %s to get the name. The issue with this, is that those two
events can be minutes, hours or even days apart. It is very dangerous to
dereference a string pointer without knowing if it still exists or not.

The proper way to handle this is to use the __string() macro in the
tracepoint which will save the string into the ring buffer at the time of
recording. Then there's no worries if the original string still exists in
memory when the ring buffer is read.

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 drivers/gpu/drm/i915/i915_trace.h | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_trace.h b/drivers/gpu/drm/i915/i915_trace.h
index 12893304c8f8..d41d914a16ca 100644
--- a/drivers/gpu/drm/i915/i915_trace.h
+++ b/drivers/gpu/drm/i915/i915_trace.h
@@ -298,16 +298,16 @@ TRACE_EVENT(intel_update_plane,
 
 	    TP_STRUCT__entry(
 			     __field(enum pipe, pipe)
-			     __field(const char *, name)
 			     __field(u32, frame)
 			     __field(u32, scanline)
 			     __array(int, src, 4)
 			     __array(int, dst, 4)
+			     __string(name, plane->name)
 			     ),
 
 	    TP_fast_assign(
+			   __assign_str(name, plane->name);
 			   __entry->pipe = crtc->pipe;
-			   __entry->name = plane->name;
 			   __entry->frame = crtc->base.dev->driver->get_vblank_counter(crtc->base.dev,
 										       crtc->pipe);
 			   __entry->scanline = intel_get_crtc_scanline(crtc);
@@ -316,7 +316,7 @@ TRACE_EVENT(intel_update_plane,
 			   ),
 
 	    TP_printk("pipe %c, plane %s, frame=%u, scanline=%u, " DRM_RECT_FP_FMT " -> " DRM_RECT_FMT,
-		      pipe_name(__entry->pipe), __entry->name,
+		      pipe_name(__entry->pipe), __get_str(name),
 		      __entry->frame, __entry->scanline,
 		      DRM_RECT_FP_ARG((const struct drm_rect *)__entry->src),
 		      DRM_RECT_ARG((const struct drm_rect *)__entry->dst))
@@ -328,21 +328,21 @@ TRACE_EVENT(intel_disable_plane,
 
 	    TP_STRUCT__entry(
 			     __field(enum pipe, pipe)
-			     __field(const char *, name)
 			     __field(u32, frame)
 			     __field(u32, scanline)
+			     __string(name, plane->name)
 			     ),
 
 	    TP_fast_assign(
+			   __assign_str(name, plane->name);
 			   __entry->pipe = crtc->pipe;
-			   __entry->name = plane->name;
 			   __entry->frame = crtc->base.dev->driver->get_vblank_counter(crtc->base.dev,
 										       crtc->pipe);
 			   __entry->scanline = intel_get_crtc_scanline(crtc);
 			   ),
 
 	    TP_printk("pipe %c, plane %s, frame=%u, scanline=%u",
-		      pipe_name(__entry->pipe), __entry->name,
+		      pipe_name(__entry->pipe), __get_str(name),
 		      __entry->frame, __entry->scanline)
 );
 
-- 
2.20.1


^ permalink raw reply related	[flat|nested] 6+ messages in thread

end of thread, other threads:[~2019-07-11 19:55 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-07-10 16:01 [PATCH] drm/i915: Copy name string into ring buffer for intel_update/disable_plane tracepoints Steven Rostedt
2019-07-10 16:44 ` ✗ Fi.CI.BAT: failure for " Patchwork
2019-07-10 17:12 ` [PATCH v2] " Ville Syrjala
2019-07-11 19:55   ` Ville Syrjälä
2019-07-11 10:44 ` ✓ Fi.CI.BAT: success for drm/i915: Copy name string into ring buffer for intel_update/disable_plane tracepoints (rev2) Patchwork
2019-07-11 18:07 ` ✓ Fi.CI.IGT: " Patchwork

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