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authorDan Carpenter <dan.carpenter@oracle.com>2014-11-27 18:57:52 +0300
committerSteven Rostedt <rostedt@goodmis.org>2014-12-03 17:10:14 -0500
commit3558a5ac50dbb2419cc649d5e154af161d661037 (patch)
tree748ba84148b99c750900206d90e5969e505726b6 /kernel/trace
parent8e1e1df29d837c589c8b4d7b49864481ff7795b8 (diff)
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tracing: Truncated output is better than nothing
The initial reason for this patch is that I noticed that: if (len > TRACE_BUF_SIZE) is off by one. In this code, if len == TRACE_BUF_SIZE, then it means we have truncated the last character off the output string. If we truncate two or more characters then we exit without printing. After some discussion, we decided that printing truncated data is better than not printing at all so we should just use vscnprintf() and remove the test entirely. Also I have updated memcpy() to copy the NUL char instead of setting the NUL in a separate step. Link: http://lkml.kernel.org/r/20141127155752.GA21914@mwanda Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace')
-rw-r--r--kernel/trace/trace.c7
1 files changed, 2 insertions, 5 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 3ce3c4ccfc94..4ceb2546c7ef 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2158,9 +2158,7 @@ __trace_array_vprintk(struct ring_buffer *buffer,
goto out;
}
- len = vsnprintf(tbuffer, TRACE_BUF_SIZE, fmt, args);
- if (len > TRACE_BUF_SIZE)
- goto out;
+ len = vscnprintf(tbuffer, TRACE_BUF_SIZE, fmt, args);
local_save_flags(flags);
size = sizeof(*entry) + len + 1;
@@ -2171,8 +2169,7 @@ __trace_array_vprintk(struct ring_buffer *buffer,
entry = ring_buffer_event_data(event);
entry->ip = ip;
- memcpy(&entry->buf, tbuffer, len);
- entry->buf[len] = '\0';
+ memcpy(&entry->buf, tbuffer, len + 1);
if (!call_filter_check_discard(call, entry, buffer, event)) {
__buffer_unlock_commit(buffer, event);
ftrace_trace_stack(buffer, flags, 6, pc);