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Subject[PATCH 1/4] [PATCH 1/4] tracing: Add pipe_close interface
From: Steven Rostedt <srostedt@redhat.com>

An ftrace plugin can add a pipe_open interface when the user opens
trace_pipe. But if the plugin allocates something within the pipe_open
it can not free it because there exists no pipe_close. The hook to
the trace file open has a corresponding close. The closing of the
trace_pipe file should also have a corresponding close.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
kernel/trace/trace.c | 4 ++++
kernel/trace/trace.h | 2 ++
2 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 874f289..f804b40 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2898,6 +2898,10 @@ static int tracing_release_pipe(struct inode *inode, struct file *file)
else
cpumask_clear_cpu(iter->cpu_file, tracing_reader_cpumask);

+
+ if (iter->trace->pipe_open)
+ iter->trace->pipe_close(iter);
+
mutex_unlock(&trace_types_lock);

free_cpumask_var(iter->started);
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 1d7f483..7fa33ca 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -272,6 +272,7 @@ struct tracer_flags {
* @pipe_open: called when the trace_pipe file is opened
* @wait_pipe: override how the user waits for traces on trace_pipe
* @close: called when the trace file is released
+ * @pipe_close: called when the trace_pipe file is released
* @read: override the default read callback on trace_pipe
* @splice_read: override the default splice_read callback on trace_pipe
* @selftest: selftest to run on boot (see trace_selftest.c)
@@ -290,6 +291,7 @@ struct tracer {
void (*pipe_open)(struct trace_iterator *iter);
void (*wait_pipe)(struct trace_iterator *iter);
void (*close)(struct trace_iterator *iter);
+ void (*pipe_close)(struct trace_iterator *iter);
ssize_t (*read)(struct trace_iterator *iter,
struct file *filp, char __user *ubuf,
size_t cnt, loff_t *ppos);
--
1.6.5



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