[PATCH][GIT PULL][v2.6.33] tracing: Remove comparing of NULL to va_list in trace_array_vprintk()

[Steven Rostedt <rostedt@goodmis.org>]

Hi Ingo,

This is an urgent fix that fixes a ARM build breakage. It is based on
the last pull request I had that fixes the function graph tracer output.


Ingo,

Please pull the latest tip/tracing/core2 tree, which can be found at:

  git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace.git
tip/tracing/core2


Carsten Emde (1):
      tracing: Remove comparing of NULL to va_list in trace_array_vprintk()

----
 kernel/trace/trace.c |   18 ++++++++++++------
 1 files changed, 12 insertions(+), 6 deletions(-)
---------------------------
commit efcf61abeb355273bc8933faf426adc366b23153
Author: Carsten Emde <Carsten.Emde@osadl.org>
Date:   Sun Dec 6 14:02:44 2009 +0100

    tracing: Remove comparing of NULL to va_list in trace_array_vprintk()
    
    Olof Johansson stated the following:
    
      Comparing a va_list with NULL is bogus. It's supposed to be treated like
      an opaque type and only be manipulated with va_* accessors.
    
    Olof noticed that this code broke the ARM builds:
    
        kernel/trace/trace.c: In function 'trace_array_vprintk':
        kernel/trace/trace.c:1364: error: invalid operands to binary == (have 'va_list' and 'void *')
        kernel/trace/trace.c: In function 'tracing_mark_write':
        kernel/trace/trace.c:3349: error: incompatible type for argument 3 of 'trace_vprintk'
    
    This patch partly reverts c13d2f7c3231e873f30db92b96c8caa48f100f33 and
    re-installs the original mark_printk() mechanism.
    
    Reported-by: Olof Johansson <olof@lixom.net>
    Signed-off-by: Carsten Emde <C.Emde@osadl.org>
    LKML-Reference: <4B1BAB74.104@osadl.org>
    Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 596dcf2..bf84e1a 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1361,11 +1361,7 @@ int trace_array_vprintk(struct trace_array *tr,
 	pause_graph_tracing();
 	raw_local_irq_save(irq_flags);
 	__raw_spin_lock(&trace_buf_lock);
-	if (args == NULL) {
-		strncpy(trace_buf, fmt, TRACE_BUF_SIZE);
-		len = strlen(trace_buf);
-	} else
-		len = vsnprintf(trace_buf, TRACE_BUF_SIZE, fmt, args);
+	len = vsnprintf(trace_buf, TRACE_BUF_SIZE, fmt, args);
 
 	size = sizeof(*entry) + len + 1;
 	buffer = tr->buffer;
@@ -3353,6 +3349,16 @@ tracing_entries_write(struct file *filp, const char __user *ubuf,
 	return cnt;
 }
 
+static int mark_printk(const char *fmt, ...)
+{
+	int ret;
+	va_list args;
+	va_start(args, fmt);
+	ret = trace_vprintk(0, fmt, args);
+	va_end(args);
+	return ret;
+}
+
 static ssize_t
 tracing_mark_write(struct file *filp, const char __user *ubuf,
 					size_t cnt, loff_t *fpos)
@@ -3379,7 +3385,7 @@ tracing_mark_write(struct file *filp, const char __user *ubuf,
 	} else
 		buf[cnt] = '\0';
 
-	cnt = trace_vprintk(0, buf, NULL);
+	cnt = mark_printk("%s", buf);
 	kfree(buf);
 	*fpos += cnt;