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authorSteven Rostedt <rostedt@goodmis.org>2008-10-28 10:44:24 -0400
committerIngo Molnar <mingo@elte.hu>2008-10-28 16:33:47 +0100
commit60063a66236c15f5613f91390631e06718689782 (patch)
tree3625c15ade69e4f8cbb85d737290da1312123241
parent21798a84ab383cdac0e7ee3368e0792b718b867d (diff)
ftrace: fix current_tracer error return
The commit (in linux-tip) c2931e05ec5965597cbfb79ad332d4a29aeceb23 ( ftrace: return an error when setting a nonexistent tracer ) added useful code that would error when a bad tracer was written into the current_tracer file. But this had a bug if the amount written was more than the amount read by that code. The first iteration would set the tracer correctly, but since it did not consume the rest of what was written (usually whitespace), the userspace utility would continue to write what was not consumed. This second iteration would fail to find a tracer and return -EINVAL. Funny thing is that the tracer would have already been set. This patch just consumes all the data that is written to the file. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r--kernel/trace/trace.c7
1 files changed, 4 insertions, 3 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index bc577dcc0e47..a610ca771558 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2377,9 +2377,10 @@ tracing_set_trace_write(struct file *filp, const char __user *ubuf,
int i;
size_t ret;
+ ret = cnt;
+
if (cnt > max_tracer_type_len)
cnt = max_tracer_type_len;
- ret = cnt;
if (copy_from_user(&buf, ubuf, cnt))
return -EFAULT;
@@ -2412,8 +2413,8 @@ tracing_set_trace_write(struct file *filp, const char __user *ubuf,
out:
mutex_unlock(&trace_types_lock);
- if (ret == cnt)
- filp->f_pos += cnt;
+ if (ret > 0)
+ filp->f_pos += ret;
return ret;
}