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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>
This commit is contained in:
Steven Rostedt 2008-05-12 21:21:01 +02:00 committed by Thomas Gleixner
parent 53d0aa7730
commit 107bad8bef
2 changed files with 36 additions and 7 deletions
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38
kernel/trace/trace.c
View File

@ -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;
}

5
kernel/trace/trace.h
View File

@ -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];