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: Pekka Paalanen <pq@iki.fi>
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 c232d82..82ced40 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -400,6 +400,26 @@
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 @@
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 @@
iter->tr->waiter = NULL;
if (signal_pending(current)) {
- read = -EINTR;
+ sret = -EINTR;
goto out;
}
@@ -2496,6 +2502,7 @@
}
while (find_next_entry_inc(iter) != NULL) {
+ int ret;
int len = iter->seq.len;
ret = print_trace_line(iter);
@@ -2526,24 +2533,16 @@
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