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authorFrederic Weisbecker <fweisbec@gmail.com>2009-03-23 22:17:01 +0100
committerIngo Molnar <mingo@elte.hu>2009-03-23 23:25:32 +0100
commit1618536961d31f9b3f55767b22d4a897f4204c26 (patch)
treef1396f4c869328dc5d6e677f6fdde571d2c6e4d7 /kernel/trace
parentc4cff064be678f1e8344d907499f2a81282edc19 (diff)
tracing/function-graph-tracer: fix functions call traces imbalance
Impact: fix traces output Sometimes one can observe an imbalance in the traces between function calls and function return traces: func1() { } } The curly brace inside func1() is the return of another function nested inside func1. The return trace have been inserted in the buffer but not the entry. We are storing a return address on the function traces stack while we haven't inserted its entry on the buffer, hence the imbalance on the traces. This is because the tracers doesn't check all failures that can happen on buffer insertion. This patch reports the tracing recursion failures and the ring buffer failures. In such cases, we now restore the original return address for the function, giving up its return trace. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> LKML-Reference: <1237843021-11695-1-git-send-email-fweisbec@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/trace')
-rw-r--r--kernel/trace/trace.c16
1 files changed, 11 insertions, 5 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 6bad12819eb..89f0c2544ad 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -924,7 +924,7 @@ trace_function(struct trace_array *tr,
}
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
-static void __trace_graph_entry(struct trace_array *tr,
+static int __trace_graph_entry(struct trace_array *tr,
struct ftrace_graph_ent *trace,
unsigned long flags,
int pc)
@@ -933,15 +933,17 @@ static void __trace_graph_entry(struct trace_array *tr,
struct ftrace_graph_ent_entry *entry;
if (unlikely(local_read(&__get_cpu_var(ftrace_cpu_disabled))))
- return;
+ return 0;
event = trace_buffer_lock_reserve(&global_trace, TRACE_GRAPH_ENT,
sizeof(*entry), flags, pc);
if (!event)
- return;
+ return 0;
entry = ring_buffer_event_data(event);
entry->graph_ent = *trace;
ring_buffer_unlock_commit(global_trace.buffer, event);
+
+ return 1;
}
static void __trace_graph_return(struct trace_array *tr,
@@ -1162,6 +1164,7 @@ int trace_graph_entry(struct ftrace_graph_ent *trace)
struct trace_array_cpu *data;
unsigned long flags;
long disabled;
+ int ret;
int cpu;
int pc;
@@ -1177,15 +1180,18 @@ int trace_graph_entry(struct ftrace_graph_ent *trace)
disabled = atomic_inc_return(&data->disabled);
if (likely(disabled == 1)) {
pc = preempt_count();
- __trace_graph_entry(tr, trace, flags, pc);
+ ret = __trace_graph_entry(tr, trace, flags, pc);
+ } else {
+ ret = 0;
}
/* Only do the atomic if it is not already set */
if (!test_tsk_trace_graph(current))
set_tsk_trace_graph(current);
+
atomic_dec(&data->disabled);
local_irq_restore(flags);
- return 1;
+ return ret;
}
void trace_graph_return(struct ftrace_graph_ret *trace)