ftrace: add trace pipe header pluggin
This patch adds a method for open_pipe and open_read to the pluggins
so that they can add a header to the trace pipe call.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index b9126ef..32f9106 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2307,11 +2307,15 @@
if (!iter)
return -ENOMEM;
+ mutex_lock(&trace_types_lock);
iter->tr = &global_trace;
iter->trace = current_trace;
-
filp->private_data = iter;
+ if (iter->trace->pipe_open)
+ iter->trace->pipe_open(iter);
+ mutex_unlock(&trace_types_lock);
+
return 0;
}
@@ -2380,13 +2384,24 @@
return cnt;
}
+ mutex_lock(&trace_types_lock);
+ if (iter->trace->read) {
+ ret = iter->trace->read(iter, filp, ubuf, cnt, ppos);
+ if (ret) {
+ read = ret;
+ goto out;
+ }
+ }
+
trace_seq_reset(&iter->seq);
start = 0;
while (trace_empty(iter)) {
- if ((filp->f_flags & O_NONBLOCK))
- return -EAGAIN;
+ if ((filp->f_flags & O_NONBLOCK)) {
+ read = -EAGAIN;
+ goto out;
+ }
/*
* This is a make-shift waitqueue. The reason we don't use
@@ -2400,16 +2415,22 @@
set_current_state(TASK_INTERRUPTIBLE);
iter->tr->waiter = current;
+ mutex_unlock(&trace_types_lock);
+
/* sleep for one second, and try again. */
schedule_timeout(HZ);
+ mutex_lock(&trace_types_lock);
+
iter->tr->waiter = NULL;
- if (signal_pending(current))
- return -EINTR;
+ if (signal_pending(current)) {
+ read = -EINTR;
+ goto out;
+ }
if (iter->trace != current_trace)
- return 0;
+ goto out;
/*
* We block until we read something and tracing is disabled.
@@ -2428,7 +2449,7 @@
/* stop when tracing is finished */
if (trace_empty(iter))
- return 0;
+ goto out;
if (cnt >= PAGE_SIZE)
cnt = PAGE_SIZE - 1;
@@ -2518,6 +2539,9 @@
if (ret)
read = -EFAULT;
+out:
+ mutex_unlock(&trace_types_lock);
+
return read;
}
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index c1ec134..ee53d70 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -135,9 +135,13 @@
void (*init)(struct trace_array *tr);
void (*reset)(struct trace_array *tr);
void (*open)(struct trace_iterator *iter);
+ void (*pipe_open)(struct trace_iterator *iter);
void (*close)(struct trace_iterator *iter);
void (*start)(struct trace_iterator *iter);
void (*stop)(struct trace_iterator *iter);
+ ssize_t (*read)(struct trace_iterator *iter,
+ struct file *filp, char __user *ubuf,
+ size_t cnt, loff_t *ppos);
void (*ctrl_update)(struct trace_array *tr);
#ifdef CONFIG_FTRACE_STARTUP_TEST
int (*selftest)(struct tracer *trace,
@@ -160,6 +164,7 @@
struct trace_iterator {
struct trace_array *tr;
struct tracer *trace;
+ void *private;
long last_overrun[NR_CPUS];
long overrun[NR_CPUS];
