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Subject[PATCH 5/5] [PATCH 5/5] tracing: Remove comparing of NULL to va_list in trace_array_vprintk()
From: Carsten Emde <Carsten.Emde@osadl.org>

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>
---
kernel/trace/trace.c | 18 ++++++++++++------
1 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 484114d..88bd9ae 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;

--
1.6.5



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