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

[Kamal Mostafa]

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-3.13.y-queue branch of the 3.13.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-3.13.y-queue

This patch is scheduled to be released in version 3.13.11.6.

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

For more information about the 3.13.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 9a36112be508a0cc8ebb1374d2bb84f9c8a646c7 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: Kamal Mostafa <kamal 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 9250479..d3db296 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -454,6 +454,9 @@ 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;
@@ -463,7 +466,7 @@ 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;

@@ -480,6 +483,7 @@ 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;
 }
@@ -497,6 +501,9 @@ 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;
@@ -504,7 +511,7 @@ 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;

@@ -513,6 +520,7 @@ 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