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From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	Ingo Molnar <mingo@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Peter Zijlstra <peterz@infradead.org>,
	linux-arch@vger.kernel.org,
	Joel Fernandes <joel@joelfernandes.org>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Andy Lutomirski <luto@kernel.org>,
	Frederic Weisbecker <frederic@kernel.org>,
	stable@kernel.org
Subject: [for-next][PATCH 17/18] function_graph: Reverse the order of pushing the ret_stack and the callback
Date: Wed, 21 Nov 2018 19:28:18 -0500	[thread overview]
Message-ID: <20181122003333.880108256@goodmis.org> (raw)
In-Reply-To: 20181122002801.501220343@goodmis.org

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

The function graph profiler uses the ret_stack to store the "subtime" and
reuse it by nested functions and also on the return. But the current logic
has the profiler callback called before the ret_stack is updated, and it is
just modifying the ret_stack that will later be allocated (it's just lucky
that the "subtime" is not touched when it is allocated).

This could also cause a crash if we are at the end of the ret_stack when
this happens.

By reversing the order of the allocating the ret_stack and then calling the
callbacks attached to a function being traced, the ret_stack entry is no
longer used before it is allocated.

Cc: stable@kernel.org
Fixes: 03274a3ffb449 ("tracing/fgraph: Adjust fgraph depth before calling trace return callback")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 kernel/trace/trace_functions_graph.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 4f0d72ae6362..2561460d7baf 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -188,15 +188,17 @@ int function_graph_enter(unsigned long ret, unsigned long func,
 	trace.func = func;
 	trace.depth = ++current->curr_ret_depth;
 
-	/* Only trace if the calling function expects to */
-	if (!ftrace_graph_entry(&trace))
-		goto out;
-
 	if (ftrace_push_return_trace(ret, func,
 				     frame_pointer, retp))
 		goto out;
 
+	/* Only trace if the calling function expects to */
+	if (!ftrace_graph_entry(&trace))
+		goto out_ret;
+
 	return 0;
+ out_ret:
+	current->curr_ret_stack--;
  out:
 	current->curr_ret_depth--;
 	return -EBUSY;
-- 
2.19.1



  parent reply	other threads:[~2018-11-22  0:34 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-22  0:28 [for-next][PATCH 00/18] function_graph: Add separate depth counter to prevent trace corruption Steven Rostedt
2018-11-22  0:28 ` [for-next][PATCH 01/18] function_graph: Create function_graph_enter() to consolidate architecture code Steven Rostedt
2018-11-22  0:28 ` [for-next][PATCH 02/18] x86/function_graph: Simplify with function_graph_entry() Steven Rostedt
2018-11-22  0:28 ` [for-next][PATCH 03/18] ARM: function_graph: " Steven Rostedt
2018-11-22  0:28 ` [for-next][PATCH 04/18] arm64: " Steven Rostedt
2018-11-27 18:07   ` Will Deacon
2018-11-27 18:26     ` Steven Rostedt
2018-11-22  0:28 ` [for-next][PATCH 05/18] microblaze: " Steven Rostedt
2018-11-22  0:28 ` [for-next][PATCH 06/18] MIPS: " Steven Rostedt
2018-11-22  0:28 ` [for-next][PATCH 07/18] nds32: " Steven Rostedt
2018-11-22  0:28 ` [for-next][PATCH 08/18] parisc: " Steven Rostedt
     [not found]   ` <20181123073033.2083020863@mail.kernel.org>
2018-11-23  9:06     ` Helge Deller
2018-11-23 17:12       ` Steven Rostedt
2018-11-23 18:34         ` Sasha Levin
2018-11-23 19:26           ` Steven Rostedt
2018-11-23 20:00             ` Sasha Levin
2018-11-24 18:46               ` Steven Rostedt
2018-12-03 14:54                 ` Sasha Levin
2018-11-22  0:28 ` [for-next][PATCH 09/18] powerpc/function_graph: " Steven Rostedt
2018-11-22  0:28 ` [for-next][PATCH 10/18] riscv/function_graph: " Steven Rostedt
2018-11-26 16:47   ` Palmer Dabbelt
2018-11-22  0:28 ` [for-next][PATCH 11/18] s390/function_graph: " Steven Rostedt
2018-11-22  6:43   ` Martin Schwidefsky
2018-11-23 17:15     ` Steven Rostedt
2018-11-22  0:28 ` [for-next][PATCH 12/18] sh/function_graph: " Steven Rostedt
2018-11-22  0:28 ` [for-next][PATCH 13/18] sparc/function_graph: " Steven Rostedt
2018-11-22  0:28 ` [for-next][PATCH 14/18] function_graph: Make ftrace_push_return_trace() static Steven Rostedt
2018-11-22  0:28 ` [for-next][PATCH 15/18] function_graph: Use new curr_ret_depth to manage depth instead of curr_ret_stack Steven Rostedt
2018-11-22 10:03   ` Peter Zijlstra
2018-11-23 14:14     ` Steven Rostedt
2018-11-22  0:28 ` [for-next][PATCH 16/18] function_graph: Move return callback before update " Steven Rostedt
2018-11-22  0:28 ` Steven Rostedt [this message]
2018-11-22  0:28 ` [for-next][PATCH 18/18] function_graph: Have profiler use curr_ret_stack and not depth Steven Rostedt
2018-11-26  5:15 ` [for-next][PATCH 00/18] function_graph: Add separate depth counter to prevent trace corruption Masami Hiramatsu
2018-11-28 20:39 ` Joe Lawrence
2018-11-28 21:00   ` Steven Rostedt
2018-11-29  3:29     ` Steven Rostedt
2018-11-29  4:24       ` Steven Rostedt
2018-11-29 15:08         ` Joe Lawrence
2018-11-29 16:17           ` Steven Rostedt
2018-11-29 16:32             ` Joe Lawrence

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