[3.11.y.z extended stable] Patch "tracing: Add ftrace_trace_stack into __trace_puts/__trace_bputs" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    tracing: Add ftrace_trace_stack into __trace_puts/__trace_bputs

to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 7bc2c3e8390e3be7973be74585060d4fcc81808b Mon Sep 17 00:00:00 2001
From: "zhangwei(Jovi)" <jovi.zhangwei at huawei.com>
Date: Thu, 18 Jul 2013 16:31:05 +0800
Subject: tracing: Add ftrace_trace_stack into __trace_puts/__trace_bputs

commit 8abfb8727f4a724d31f9ccfd8013fbd16d539445 upstream.

Currently trace option stacktrace is not applicable for
trace_printk with constant string argument, the reason is
in __trace_puts/__trace_bputs ftrace_trace_stack is missing.

In contrast, when using trace_printk with non constant string
argument(will call into __trace_printk/__trace_bprintk), then
trace option stacktrace is workable, this inconstant result
will confuses users a lot.

Link: http://lkml.kernel.org/p/51E7A7C9.9040401@huawei.com

Signed-off-by: zhangwei(Jovi) <jovi.zhangwei at huawei.com>
Signed-off-by: Steven Rostedt <rostedt at goodmis.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 kernel/trace/trace.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index c8b8717afc23..c75803fba4b9 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -434,6 +434,9 @@ int __trace_puts(unsigned long ip, const char *str, int size)
 	struct print_entry *entry;
 	unsigned long irq_flags;
 	int alloc;
+	int pc;
+
+	pc = preempt_count();

 	if (unlikely(tracing_selftest_running || tracing_disabled))
 		return 0;
@@ -443,7 +446,7 @@ int __trace_puts(unsigned long ip, const char *str, int size)
 	local_save_flags(irq_flags);
 	buffer = global_trace.trace_buffer.buffer;
 	event = trace_buffer_lock_reserve(buffer, TRACE_PRINT, alloc,
-					  irq_flags, preempt_count());
+					  irq_flags, pc);
 	if (!event)
 		return 0;

@@ -460,6 +463,7 @@ int __trace_puts(unsigned long ip, const char *str, int size)
 		entry->buf[size] = '\0';

 	__buffer_unlock_commit(buffer, event);
+	ftrace_trace_stack(buffer, irq_flags, 4, pc);

 	return size;
 }
@@ -477,6 +481,9 @@ int __trace_bputs(unsigned long ip, const char *str)
 	struct bputs_entry *entry;
 	unsigned long irq_flags;
 	int size = sizeof(struct bputs_entry);
+	int pc;
+
+	pc = preempt_count();

 	if (unlikely(tracing_selftest_running || tracing_disabled))
 		return 0;
@@ -484,7 +491,7 @@ int __trace_bputs(unsigned long ip, const char *str)
 	local_save_flags(irq_flags);
 	buffer = global_trace.trace_buffer.buffer;
 	event = trace_buffer_lock_reserve(buffer, TRACE_BPUTS, size,
-					  irq_flags, preempt_count());
+					  irq_flags, pc);
 	if (!event)
 		return 0;

@@ -493,6 +500,7 @@ int __trace_bputs(unsigned long ip, const char *str)
 	entry->str			= str;

 	__buffer_unlock_commit(buffer, event);
+	ftrace_trace_stack(buffer, irq_flags, 4, pc);

 	return 1;
 }
--
1.9.1