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ftrace: add readpos to struct trace_seq; add trace_seq_to_user()

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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>
This commit is contained in:
Pekka Paalanen 2008-05-12 21:21:02 +02:00 committed by Thomas Gleixner
parent 2bb6f8d638
commit 6c6c27969a
2 changed files with 39 additions and 37 deletions
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73
kernel/trace/trace.c
View File

@ -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

3
kernel/trace/trace.h
View File

@ -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;