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 (file)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2307,11 +2307,15 @@ static int tracing_open_pipe(struct inode *inode, struct file *filp)
        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 @@ tracing_read_pipe(struct file *filp, char __user *ubuf,
                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 @@ tracing_read_pipe(struct file *filp, char __user *ubuf,
                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 @@ tracing_read_pipe(struct file *filp, char __user *ubuf,
 
        /* 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 @@ tracing_read_pipe(struct file *filp, char __user *ubuf,
        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 (file)
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -135,9 +135,13 @@ struct tracer {
        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_seq {
 struct trace_iterator {
        struct trace_array      *tr;
        struct tracer           *trace;
+       void                    *private;
        long                    last_overrun[NR_CPUS];
        long                    overrun[NR_CPUS];