From: Steven Rostedt Date: Tue, 28 Oct 2008 14:44:24 +0000 (-0400) Subject: ftrace: fix current_tracer error return X-Git-Tag: v2.6.28-rc3~86^2 X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=60063a66236c15f5613f91390631e06718689782;p=linux-2.6-omap-h63xx.git 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 Signed-off-by: Ingo Molnar --- diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index bc577dcc0e4..a610ca77155 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; }