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>
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Родитель
2bb6f8d638
Коммит
6c6c27969a
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@ -400,6 +400,26 @@ static void
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trace_seq_reset(struct trace_seq *s)
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{
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s->len = 0;
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s->readpos = 0;
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}
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ssize_t trace_seq_to_user(struct trace_seq *s, char __user *ubuf, size_t cnt)
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{
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int len;
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int ret;
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if (s->len <= s->readpos)
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return -EBUSY;
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len = s->len - s->readpos;
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if (cnt > len)
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cnt = len;
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ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt);
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if (ret)
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return -EFAULT;
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s->readpos += len;
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return cnt;
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}
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static void
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@ -2361,46 +2381,32 @@ tracing_read_pipe(struct file *filp, char __user *ubuf,
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struct trace_iterator *iter = filp->private_data;
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struct trace_array_cpu *data;
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static cpumask_t mask;
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static int start;
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unsigned long flags;
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#ifdef CONFIG_FTRACE
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int ftrace_save;
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#endif
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int read = 0;
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int cpu;
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int len;
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int ret;
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ssize_t sret;
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/* return any leftover data */
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if (iter->seq.len > start) {
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len = iter->seq.len - start;
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if (cnt > len)
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cnt = len;
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ret = copy_to_user(ubuf, iter->seq.buffer + start, cnt);
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if (ret)
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cnt = -EFAULT;
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sret = trace_seq_to_user(&iter->seq, ubuf, cnt);
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if (sret != -EBUSY)
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return sret;
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sret = 0;
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start += len;
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return cnt;
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}
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trace_seq_reset(&iter->seq);
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mutex_lock(&trace_types_lock);
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if (iter->trace->read) {
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ret = iter->trace->read(iter, filp, ubuf, cnt, ppos);
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if (ret) {
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read = ret;
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sret = iter->trace->read(iter, filp, ubuf, cnt, ppos);
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if (sret)
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goto out;
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}
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}
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trace_seq_reset(&iter->seq);
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start = 0;
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while (trace_empty(iter)) {
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if ((filp->f_flags & O_NONBLOCK)) {
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read = -EAGAIN;
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sret = -EAGAIN;
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goto out;
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}
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@ -2426,7 +2432,7 @@ tracing_read_pipe(struct file *filp, char __user *ubuf,
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iter->tr->waiter = NULL;
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if (signal_pending(current)) {
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read = -EINTR;
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sret = -EINTR;
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goto out;
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}
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@ -2496,6 +2502,7 @@ tracing_read_pipe(struct file *filp, char __user *ubuf,
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}
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while (find_next_entry_inc(iter) != NULL) {
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int ret;
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int len = iter->seq.len;
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ret = print_trace_line(iter);
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@ -2526,24 +2533,16 @@ tracing_read_pipe(struct file *filp, char __user *ubuf,
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local_irq_restore(flags);
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/* Now copy what we have to the user */
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read = iter->seq.len;
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if (read > cnt)
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read = cnt;
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ret = copy_to_user(ubuf, iter->seq.buffer, read);
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if (read < iter->seq.len)
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start = read;
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else
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sret = trace_seq_to_user(&iter->seq, ubuf, cnt);
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if (iter->seq.readpos >= iter->seq.len)
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trace_seq_reset(&iter->seq);
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if (ret)
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read = -EFAULT;
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if (sret == -EBUSY)
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sret = 0;
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out:
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mutex_unlock(&trace_types_lock);
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return read;
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return sret;
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}
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static ssize_t
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@ -155,6 +155,7 @@ struct tracer {
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struct trace_seq {
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unsigned char buffer[PAGE_SIZE];
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unsigned int len;
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unsigned int readpos;
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};
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/*
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@ -301,6 +302,8 @@ extern int trace_selftest_startup_sched_switch(struct tracer *trace,
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extern void *head_page(struct trace_array_cpu *data);
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extern int trace_seq_printf(struct trace_seq *s, const char *fmt, ...);
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extern ssize_t trace_seq_to_user(struct trace_seq *s, char __user *ubuf,
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size_t cnt);
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extern long ns2usecs(cycle_t nsec);
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extern unsigned long trace_flags;
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