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For the signals with global handlers, the handler is reset to SIG_DFL and the handler is called under a lock, so there is no race if signal() is called again from the handler to reassert itself as the handler. For the signals with per-thread handlers, the state is local to the thread and resultantly there is no opportunity for a race.
Exceptions
SIG34-C-EX1: For implementations with persistent signal handlers, it is safe for a handler to modify the behavior of its own signal. Behavior modifications include ignoring the signal, resetting to the default behavior, and having the signal handled by a different handler. A handler reasserting its binding is also safe but unnecessary.
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