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authorSteven Rostedt <rostedt@goodmis.org>2008-10-28 10:44:24 -0400
committerIngo Molnar <mingo@elte.hu>2008-10-28 11:33:47 -0400
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,
2377 int i; 2377 int i;
2378 size_t ret; 2378 size_t ret;
2379 2379
2380 ret = cnt;
2381
2380 if (cnt > max_tracer_type_len) 2382 if (cnt > max_tracer_type_len)
2381 cnt = max_tracer_type_len; 2383 cnt = max_tracer_type_len;
2382 ret = cnt;
2383 2384
2384 if (copy_from_user(&buf, ubuf, cnt)) 2385 if (copy_from_user(&buf, ubuf, cnt))
2385 return -EFAULT; 2386 return -EFAULT;
@@ -2412,8 +2413,8 @@ tracing_set_trace_write(struct file *filp, const char __user *ubuf,
2412 out: 2413 out:
2413 mutex_unlock(&trace_types_lock); 2414 mutex_unlock(&trace_types_lock);
2414 2415
2415 if (ret == cnt) 2416 if (ret > 0)
2416 filp->f_pos += cnt; 2417 filp->f_pos += ret;
2417 2418
2418 return ret; 2419 return ret;
2419} 2420}