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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>
This commit is contained in:
Eduard - Gabriel Munteanu 2009-02-09 08:15:55 +02:00 committed by Steven Rostedt
parent 3c56819b14
commit ff98781bab
1 changed files with 63 additions and 52 deletions
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115
kernel/trace/trace.c
View File

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