1UTRACE_BARRIER(9)               utrace core API              UTRACE_BARRIER(9)
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NAME

6       utrace_barrier - synchronize with simultaneous tracing callbacks
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SYNOPSIS

9       int utrace_barrier(struct task_struct * target,
10                          struct utrace_engine * engine);
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ARGUMENTS

13       target
14           thread to affect
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16       engine
17           engine to affect (can be detached)
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DESCRIPTION

20       This blocks while target might be in the midst of making a callback to
21       engine. It can be interrupted by signals and will return -ERESTARTSYS.
22       A return value of zero means no callback from target to engine was in
23       progress. Any effect of its return value (such as UTRACE_STOP) has
24       already been applied to engine.
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26       It's not necessary to keep the target pointer alive for this call. It's
27       only necessary to hold a ref on engine. This will return safely even if
28       target has been reaped and has no task refs.
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30       A successful return from utrace_barrier guarantees its ordering with
31       respect to utrace_set_events and utrace_control calls. If target was
32       not properly stopped, event callbacks just disabled might still be in
33       progress; utrace_barrier waits until there is no chance an unwanted
34       callback can be in progress.
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38Kernel Hackers Manual 2.6.       November 2011               UTRACE_BARRIER(9)
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