[PATCH 08/15] tracing: Make kmem memory allocation tracepoints conditional

[Tom Zanussi]

Making the memory allocation tracepoints conditional allows those
events to be traced using the functions containing them e.g. the
kmalloc_trace() handler can itself use kmalloc() in the trace path,
which otherwise wouldn't be possible.

The TP_CONDITION simply tests gfp_flags for the newly introduced
___GFP_NOTRACE and if true, the tracepoint simply returns without
tracing.

This allows _notrace versions of the memory allocation functions to be
defined, which do the same thing as the normal versions but in
addition set the ___GFP_NOTRACE flag, and thus avoid the (possibly
indirect) recursive calls to themselves.

Signed-off-by: Tom Zanussi <tom.zanussi@xxxxxxxxxxxxxxx>
---
 include/trace/events/kmem.h | 28 +++++++++++++++++++---------
 1 file changed, 19 insertions(+), 9 deletions(-)

diff --git a/include/trace/events/kmem.h b/include/trace/events/kmem.h
index aece134..6d34eed 100644
--- a/include/trace/events/kmem.h
+++ b/include/trace/events/kmem.h
@@ -42,20 +42,24 @@ DECLARE_EVENT_CLASS(kmem_alloc,
 		show_gfp_flags(__entry->gfp_flags))
 );
 
-DEFINE_EVENT(kmem_alloc, kmalloc,
+DEFINE_EVENT_CONDITION(kmem_alloc, kmalloc,
 
 	TP_PROTO(unsigned long call_site, const void *ptr,
 		 size_t bytes_req, size_t bytes_alloc, gfp_t gfp_flags),
 
-	TP_ARGS(call_site, ptr, bytes_req, bytes_alloc, gfp_flags)
+	TP_ARGS(call_site, ptr, bytes_req, bytes_alloc, gfp_flags),
+
+	TP_CONDITION(!(gfp_flags & ___GFP_NOTRACE))
 );
 
-DEFINE_EVENT(kmem_alloc, kmem_cache_alloc,
+DEFINE_EVENT_CONDITION(kmem_alloc, kmem_cache_alloc,
 
 	TP_PROTO(unsigned long call_site, const void *ptr,
 		 size_t bytes_req, size_t bytes_alloc, gfp_t gfp_flags),
 
-	TP_ARGS(call_site, ptr, bytes_req, bytes_alloc, gfp_flags)
+	TP_ARGS(call_site, ptr, bytes_req, bytes_alloc, gfp_flags),
+
+	TP_CONDITION(!(gfp_flags & ___GFP_NOTRACE))
 );
 
 DECLARE_EVENT_CLASS(kmem_alloc_node,
@@ -96,22 +100,26 @@ DECLARE_EVENT_CLASS(kmem_alloc_node,
 		__entry->node)
 );
 
-DEFINE_EVENT(kmem_alloc_node, kmalloc_node,
+DEFINE_EVENT_CONDITION(kmem_alloc_node, kmalloc_node,
 
 	TP_PROTO(unsigned long call_site, const void *ptr,
 		 size_t bytes_req, size_t bytes_alloc,
 		 gfp_t gfp_flags, int node),
 
-	TP_ARGS(call_site, ptr, bytes_req, bytes_alloc, gfp_flags, node)
+	TP_ARGS(call_site, ptr, bytes_req, bytes_alloc, gfp_flags, node),
+
+	TP_CONDITION(!(gfp_flags & ___GFP_NOTRACE))
 );
 
-DEFINE_EVENT(kmem_alloc_node, kmem_cache_alloc_node,
+DEFINE_EVENT_CONDITION(kmem_alloc_node, kmem_cache_alloc_node,
 
 	TP_PROTO(unsigned long call_site, const void *ptr,
 		 size_t bytes_req, size_t bytes_alloc,
 		 gfp_t gfp_flags, int node),
 
-	TP_ARGS(call_site, ptr, bytes_req, bytes_alloc, gfp_flags, node)
+	TP_ARGS(call_site, ptr, bytes_req, bytes_alloc, gfp_flags, node),
+
+	TP_CONDITION(!(gfp_flags & ___GFP_NOTRACE))
 );
 
 DECLARE_EVENT_CLASS(kmem_free,
@@ -191,13 +199,15 @@ TRACE_EVENT(mm_page_free_batched,
 			__entry->cold)
 );
 
-TRACE_EVENT(mm_page_alloc,
+TRACE_EVENT_CONDITION(mm_page_alloc,
 
 	TP_PROTO(struct page *page, unsigned int order,
 			gfp_t gfp_flags, int migratetype),
 
 	TP_ARGS(page, order, gfp_flags, migratetype),
 
+	TP_CONDITION(!(gfp_flags & ___GFP_NOTRACE)),
+
 	TP_STRUCT__entry(
 		__field(	struct page *,	page		)
 		__field(	unsigned int,	order		)
-- 
1.9.3

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