tracing: Turn event/id->i_private into call->event.type
event_id_read() is racy, ftrace_event_call can be already freed by trace_remove_event_call() callers. Change event_create_dir() to pass "data = call->event.type", this is all event_id_read() needs. ftrace_event_id_fops no longer needs tracing_open_generic(). We add the new helper, event_file_data(), to read ->i_private, it will have more users. Note: currently ACCESS_ONCE() and "id != 0" check are not needed, but we are going to change event_remove/rmdir to clear ->i_private. Link: http://lkml.kernel.org/r/20130726172532.GA3605@redhat.com Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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@ -409,6 +409,11 @@ static void put_system(struct ftrace_subsystem_dir *dir)
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mutex_unlock(&event_mutex);
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}
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static void *event_file_data(struct file *filp)
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{
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return ACCESS_ONCE(file_inode(filp)->i_private);
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}
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/*
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* Open and update trace_array ref count.
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* Must have the current trace_array passed to it.
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@ -946,14 +951,18 @@ static int trace_format_open(struct inode *inode, struct file *file)
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static ssize_t
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event_id_read(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos)
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{
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struct ftrace_event_call *call = filp->private_data;
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int id = (long)event_file_data(filp);
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char buf[32];
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int len;
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if (*ppos)
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return 0;
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len = sprintf(buf, "%d\n", call->event.type);
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if (unlikely(!id))
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return -ENODEV;
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len = sprintf(buf, "%d\n", id);
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return simple_read_from_buffer(ubuf, cnt, ppos, buf, len);
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}
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@ -1240,7 +1249,6 @@ static const struct file_operations ftrace_event_format_fops = {
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};
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static const struct file_operations ftrace_event_id_fops = {
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.open = tracing_open_generic,
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.read = event_id_read,
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.llseek = default_llseek,
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};
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@ -1488,8 +1496,8 @@ event_create_dir(struct dentry *parent,
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#ifdef CONFIG_PERF_EVENTS
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if (call->event.type && call->class->reg)
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trace_create_file("id", 0444, file->dir, call,
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id);
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trace_create_file("id", 0444, file->dir,
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(void *)(long)call->event.type, id);
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#endif
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/*
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