[PATCH 3/3] usage: do not check die recursion outside main thread

When we have started threads with the async subsystem, both the thread and the main program may call die(). The async subsystem sets up a special die routine to call pthread_exit rather than regular exit, but the recursion check in die() happens outside of this routine, and does not know that it's OK for two dies to run.

As a result, we may print "recursion in die handler" when an async thread dies, even though there is no recursion. This can be triggered, for example, by upload-pack errors; the receiving side will die both in the async sideband demultiplexer and in the main program.

This patch teaches the recursion check to use the same running_main_thread() check that the async code bases its exit decision on. That means we detect only recursion within the main program itself, and assume that async handlers correctly die (which they do).

Signed-off-by: Jeff King <peff@peff.net>
---
This is the simplest solution. You could actually have a thread-local
dying counter, which would detect die recursion within an async thread.
But I did not want to get into designing a lowest-common-denominator of
thread-local storage that would work on all of our platforms.

 usage.c | 4 ++++
 1 file changed, 4 insertions(+)