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Commit 6c6c2796 authored by Pekka Paalanen's avatar Pekka Paalanen Committed by Thomas Gleixner
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ftrace: add readpos to struct trace_seq; add trace_seq_to_user() 



Refactor code from tracing_read_pipe() and create trace_seq_to_user().
Moved trace_seq_reset() call before iter->trace->read() call so that
when all leftover data is returned, trace_seq is reset automatically.

Signed-off-by: default avatarPekka Paalanen <pq@iki.fi>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 2bb6f8d6

kernel/trace/trace.c

+36 −37
Original line number Diff line number Diff line
@@ -400,6 +400,26 @@ static void 
trace_seq_reset(struct trace_seq *s)

{

	s->len = 0;

	s->readpos = 0;

}



ssize_t trace_seq_to_user(struct trace_seq *s, char __user *ubuf, size_t cnt)

{

	int len;

	int ret;



	if (s->len <= s->readpos)

		return -EBUSY;



	len = s->len - s->readpos;

	if (cnt > len)

		cnt = len;

	ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt);

	if (ret)

		return -EFAULT;



	s->readpos += len;

	return cnt;

}



static void
@@ -2361,46 +2381,32 @@ tracing_read_pipe(struct file *filp, char __user *ubuf, 
	struct trace_iterator *iter = filp->private_data;

	struct trace_array_cpu *data;

	static cpumask_t mask;

	static int start;

	unsigned long flags;

#ifdef CONFIG_FTRACE

	int ftrace_save;

#endif

	int read = 0;

	int cpu;

	int len;

	int ret;

	ssize_t sret;



	/* return any leftover data */

	if (iter->seq.len > start) {

		len = iter->seq.len - start;

		if (cnt > len)

			cnt = len;

		ret = copy_to_user(ubuf, iter->seq.buffer + start, cnt);

		if (ret)

			cnt = -EFAULT;

	sret = trace_seq_to_user(&iter->seq, ubuf, cnt);

	if (sret != -EBUSY)

		return sret;

	sret = 0;



		start += len;



		return cnt;

	}

	trace_seq_reset(&iter->seq);



	mutex_lock(&trace_types_lock);

	if (iter->trace->read) {

		ret = iter->trace->read(iter, filp, ubuf, cnt, ppos);

		if (ret) {

			read = ret;

		sret = iter->trace->read(iter, filp, ubuf, cnt, ppos);

		if (sret)

			goto out;

	}

	}



	trace_seq_reset(&iter->seq);

	start = 0;



	while (trace_empty(iter)) {



		if ((filp->f_flags & O_NONBLOCK)) {

			read = -EAGAIN;

			sret = -EAGAIN;

			goto out;

		}
@@ -2426,7 +2432,7 @@ tracing_read_pipe(struct file *filp, char __user *ubuf, 
		iter->tr->waiter = NULL;



		if (signal_pending(current)) {

			read = -EINTR;

			sret = -EINTR;

			goto out;

		}
@@ -2496,6 +2502,7 @@ tracing_read_pipe(struct file *filp, char __user *ubuf, 
	}



	while (find_next_entry_inc(iter) != NULL) {

		int ret;

		int len = iter->seq.len;



		ret = print_trace_line(iter);
@@ -2526,24 +2533,16 @@ tracing_read_pipe(struct file *filp, char __user *ubuf, 
	local_irq_restore(flags);



	/* Now copy what we have to the user */

	read = iter->seq.len;

	if (read > cnt)

		read = cnt;



	ret = copy_to_user(ubuf, iter->seq.buffer, read);



	if (read < iter->seq.len)

		start = read;

	else

	sret = trace_seq_to_user(&iter->seq, ubuf, cnt);

	if (iter->seq.readpos >= iter->seq.len)

		trace_seq_reset(&iter->seq);



	if (ret)

		read = -EFAULT;

	if (sret == -EBUSY)

		sret = 0;



out:

	mutex_unlock(&trace_types_lock);



	return read;

	return sret;

}



static ssize_t

kernel/trace/trace.h

+3 −0
Original line number Diff line number Diff line
@@ -155,6 +155,7 @@ struct tracer { 
struct trace_seq {

	unsigned char		buffer[PAGE_SIZE];

	unsigned int		len;

	unsigned int		readpos;

};



/*
@@ -301,6 +302,8 @@ extern int trace_selftest_startup_sched_switch(struct tracer *trace, 


extern void *head_page(struct trace_array_cpu *data);

extern int trace_seq_printf(struct trace_seq *s, const char *fmt, ...);

extern ssize_t trace_seq_to_user(struct trace_seq *s, char __user *ubuf,

				 size_t cnt);

extern long ns2usecs(cycle_t nsec);



extern unsigned long trace_flags;