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tracing: Move pipe waiting code out of tracing_read_pipe().
This moves the pipe waiting code from tracing_read_pipe() into tracing_wait_pipe(), which is useful to implement other fops, like splice_read. Signed-off-by: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro> Signed-off-by: Steven Rostedt <srostedt@redhat.com>
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3c56819b14
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@ -2388,6 +2388,63 @@ tracing_poll_pipe(struct file *filp, poll_table *poll_table)
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}
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}
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/* Must be called with trace_types_lock mutex held. */
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static int tracing_wait_pipe(struct file *filp)
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{
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struct trace_iterator *iter = filp->private_data;
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while (trace_empty(iter)) {
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if ((filp->f_flags & O_NONBLOCK)) {
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return -EAGAIN;
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}
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/*
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* This is a make-shift waitqueue. The reason we don't use
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* an actual wait queue is because:
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* 1) we only ever have one waiter
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* 2) the tracing, traces all functions, we don't want
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* the overhead of calling wake_up and friends
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* (and tracing them too)
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* Anyway, this is really very primitive wakeup.
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*/
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set_current_state(TASK_INTERRUPTIBLE);
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iter->tr->waiter = current;
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mutex_unlock(&trace_types_lock);
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/* sleep for 100 msecs, and try again. */
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schedule_timeout(HZ/10);
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mutex_lock(&trace_types_lock);
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iter->tr->waiter = NULL;
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if (signal_pending(current)) {
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return -EINTR;
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}
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if (iter->trace != current_trace)
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return 0;
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/*
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* We block until we read something and tracing is disabled.
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* We still block if tracing is disabled, but we have never
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* read anything. This allows a user to cat this file, and
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* then enable tracing. But after we have read something,
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* we give an EOF when tracing is again disabled.
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*
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* iter->pos will be 0 if we haven't read anything.
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*/
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if (!tracer_enabled && iter->pos)
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break;
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continue;
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}
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return 1;
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}
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/*
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* Consumer reader.
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*/
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@ -2413,61 +2470,15 @@ tracing_read_pipe(struct file *filp, char __user *ubuf,
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}
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waitagain:
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sret = 0;
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while (trace_empty(iter)) {
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if ((filp->f_flags & O_NONBLOCK)) {
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sret = -EAGAIN;
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goto out;
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}
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/*
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* This is a make-shift waitqueue. The reason we don't use
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* an actual wait queue is because:
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* 1) we only ever have one waiter
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* 2) the tracing, traces all functions, we don't want
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* the overhead of calling wake_up and friends
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* (and tracing them too)
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* Anyway, this is really very primitive wakeup.
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*/
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set_current_state(TASK_INTERRUPTIBLE);
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iter->tr->waiter = current;
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mutex_unlock(&trace_types_lock);
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/* sleep for 100 msecs, and try again. */
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schedule_timeout(HZ/10);
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mutex_lock(&trace_types_lock);
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iter->tr->waiter = NULL;
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if (signal_pending(current)) {
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sret = -EINTR;
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goto out;
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}
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if (iter->trace != current_trace)
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goto out;
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/*
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* We block until we read something and tracing is disabled.
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* We still block if tracing is disabled, but we have never
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* read anything. This allows a user to cat this file, and
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* then enable tracing. But after we have read something,
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* we give an EOF when tracing is again disabled.
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*
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* iter->pos will be 0 if we haven't read anything.
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*/
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if (!tracer_enabled && iter->pos)
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break;
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continue;
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}
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sret = tracing_wait_pipe(filp);
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if (sret <= 0)
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goto out;
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/* stop when tracing is finished */
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if (trace_empty(iter))
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if (trace_empty(iter)) {
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sret = 0;
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goto out;
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}
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if (cnt >= PAGE_SIZE)
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cnt = PAGE_SIZE - 1;
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