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Subject[PATCH] ftrace: fix trace_marker output
When a string was written to <debugfs>/tracing/trace_marker, some
strange characters appeared in the trace output instead of the
string, since a vprint function erroneously called a vararg print
function with a va_list argument. This patch fixes the problem and
simplifies the related code.

Signed-off-by: Carsten Emde <C.Emde@osadl.org>

Index: linux-2.6.31.6-rt19/kernel/trace/trace.c
===================================================================
--- linux-2.6.31.6-rt19.orig/kernel/trace/trace.c
+++ linux-2.6.31.6-rt19/kernel/trace/trace.c
@@ -1376,10 +1376,11 @@ int trace_array_vprintk(struct trace_arr
pause_graph_tracing();
raw_local_irq_save(irq_flags);
__raw_spin_lock(&trace_buf_lock);
- len = vsnprintf(trace_buf, TRACE_BUF_SIZE, fmt, args);
-
- len = min(len, TRACE_BUF_SIZE-1);
- trace_buf[len] = 0;
+ if (args == NULL) {
+ strncpy(trace_buf, fmt, TRACE_BUF_SIZE);
+ len = strlen(trace_buf);
+ } else
+ len = vsnprintf(trace_buf, TRACE_BUF_SIZE, fmt, args);

size = sizeof(*entry) + len + 1;
buffer = tr->buffer;
@@ -1388,10 +1389,10 @@ int trace_array_vprintk(struct trace_arr
if (!event)
goto out_unlock;
entry = ring_buffer_event_data(event);
- entry->ip = ip;
+ entry->ip = ip;

memcpy(&entry->buf, trace_buf, len);
- entry->buf[len] = 0;
+ entry->buf[len] = '\0';
if (!filter_check_discard(call, entry, buffer, event))
ring_buffer_unlock_commit(buffer, event);

@@ -1408,7 +1409,7 @@ int trace_array_vprintk(struct trace_arr

int trace_vprintk(unsigned long ip, const char *fmt, va_list args)
{
- return trace_array_printk(&global_trace, ip, fmt, args);
+ return trace_array_vprintk(&global_trace, ip, fmt, args);
}
EXPORT_SYMBOL_GPL(trace_vprintk);

@@ -3336,22 +3337,11 @@ tracing_entries_write(struct file *filp,
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)
{
char *buf;
- char *end;

if (tracing_disabled)
return -EINVAL;
@@ -3359,7 +3349,7 @@ tracing_mark_write(struct file *filp, co
if (cnt > TRACE_BUF_SIZE)
cnt = TRACE_BUF_SIZE;

- buf = kmalloc(cnt + 1, GFP_KERNEL);
+ buf = kmalloc(cnt + 2, GFP_KERNEL);
if (buf == NULL)
return -ENOMEM;

@@ -3367,14 +3357,13 @@ tracing_mark_write(struct file *filp, co
kfree(buf);
return -EFAULT;
}
+ if (buf[cnt-1] != '\n') {
+ buf[cnt] = '\n';
+ buf[cnt+1] = '\0';
+ } else
+ buf[cnt] = '\0';

- /* Cut from the first nil or newline. */
- buf[cnt] = '\0';
- end = strchr(buf, '\n');
- if (end)
- *end = '\0';
-
- cnt = mark_printk("%s\n", buf);
+ cnt = trace_vprintk(0, buf, NULL);
kfree(buf);
*fpos += cnt;


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