X-Git-Url: http://git.lttng.org/?a=blobdiff_plain;f=lttng-context-callstack.c;h=2fa5f52dbf19929ff2686a1e594dc5d22cbd724a;hb=a2b0231a9ae996cc69e48d75c338ad7d081a0f85;hp=bdc1761ee705669ad8d7c95c8edeede0b434cb34;hpb=12c1f012312009f2af95757306aa51af792f1bf6;p=lttng-modules.git

diff --git a/lttng-context-callstack.c b/lttng-context-callstack.c
index bdc1761e..2fa5f52d 100644
--- a/lttng-context-callstack.c
+++ b/lttng-context-callstack.c
@@ -32,7 +32,7 @@
  *
  *   size = cpus * nest * depth * sizeof(unsigned long)
  *
- * Which is about 800 bytes per CPU on 64-bit host and a depth of 25.
+ * Which is 4096 bytes per CPU on 64-bit host and a depth of 128.
  * The allocation is done at the initialization to avoid memory
  * allocation overhead while tracing, using a shallow stack.
  *
@@ -62,7 +62,7 @@
 #include "wrapper/vmalloc.h"
 #include "lttng-tracer.h"
 
-#define MAX_ENTRIES 25
+#define MAX_ENTRIES 128
 
 enum lttng_cs_ctx_modes {
 	CALLSTACK_KERNEL = 0,
@@ -120,14 +120,26 @@ int init_type(enum lttng_cs_ctx_modes mode)
 	return 0;
 }
 
+/* Keep track of nesting inside userspace callstack context code */
+DEFINE_PER_CPU(int, callstack_user_nesting);
+
 static
 struct stack_trace *stack_trace_context(struct lttng_ctx_field *field,
 					struct lib_ring_buffer_ctx *ctx)
 {
-	int nesting;
+	int buffer_nesting, cs_user_nesting;
 	struct lttng_cs *cs;
 	struct field_data *fdata = field->priv;
 
+	/*
+	 * Do not gather the userspace callstack context when the event was
+	 * triggered by the userspace callstack context saving mechanism.
+	 */
+	cs_user_nesting = per_cpu(callstack_user_nesting, ctx->cpu);
+
+	if (fdata->mode == CALLSTACK_USER && cs_user_nesting >= 1)
+		return NULL;
+
 	/*
 	 * get_cpu() is not required, preemption is already
 	 * disabled while event is written.
@@ -136,11 +148,11 @@ struct stack_trace *stack_trace_context(struct lttng_ctx_field *field,
 	 * Check it again as a safety net.
 	 */
 	cs = per_cpu_ptr(fdata->cs_percpu, ctx->cpu);
-	nesting = per_cpu(lib_ring_buffer_nesting, ctx->cpu) - 1;
-	if (nesting >= RING_BUFFER_MAX_NESTING) {
+	buffer_nesting = per_cpu(lib_ring_buffer_nesting, ctx->cpu) - 1;
+	if (buffer_nesting >= RING_BUFFER_MAX_NESTING)
 		return NULL;
-	}
-	return &cs->dispatch[nesting].stack_trace;
+
+	return &cs->dispatch[buffer_nesting].stack_trace;
 }
 
 /*
@@ -168,8 +180,15 @@ size_t lttng_callstack_get_size(size_t offset, struct lttng_ctx_field *field,
 	/* reset stack trace, no need to clear memory */
 	trace->nr_entries = 0;
 
+	if (fdata->mode == CALLSTACK_USER)
+		++per_cpu(callstack_user_nesting, ctx->cpu);
+
 	/* do the real work and reserve space */
 	cs_types[fdata->mode].save_func(trace);
+
+	if (fdata->mode == CALLSTACK_USER)
+		per_cpu(callstack_user_nesting, ctx->cpu)--;
+
 	/*
 	 * Remove final ULONG_MAX delimiter. If we cannot find it, add
 	 * our own marker to show that the stack is incomplete. This is