Fix a deadlock in channels, again. #12352
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This deadlock was caused when the channel was closed at just the right time, so the extra `self.cnt.fetch_add` actually should have preserved the DISCONNECTED state of the channel. by modifying this the channel entered a state such that the port would never succeed in dropping. This also moves the increment of self.steals until after the MAX_STEALS block. The reason for this is that in 'fn recv()' the steals variable is decremented immediately after the try_recv(), which could in theory set steals to -1 if it was previously set to 0 in try_recv(). Closes rust-lang#12340
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This deadlock was caused when the channel was closed at just the right time, so the extra `self.cnt.fetch_add` actually should have preserved the DISCONNECTED state of the channel. by modifying this the channel entered a state such that the port would never succeed in dropping. This also moves the increment of self.steals until after the MAX_STEALS block. The reason for this is that in 'fn recv()' the steals variable is decremented immediately after the try_recv(), which could in theory set steals to -1 if it was previously set to 0 in try_recv(). Closes #12340
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This deadlock was caused when the channel was closed at just the right time, so
the extra
self.cnt.fetch_addactually should have preserved the DISCONNECTEDstate of the channel. by modifying this the channel entered a state such that
the port would never succeed in dropping.
This also moves the increment of self.steals until after the MAX_STEALS block.
The reason for this is that in 'fn recv()' the steals variable is decremented
immediately after the try_recv(), which could in theory set steals to -1 if it
was previously set to 0 in try_recv().
Closes #12340