device: 0.790
instruction: 0.629
graphic: 0.537
socket: 0.488
network: 0.422
vnc: 0.411
semantic: 0.395
boot: 0.302
mistranslation: 0.080
other: 0.068
KVM: 0.065
assembly: 0.015

windows serial COM PollingFunc don't sleep if guest uart can't write
Description of problem:
If two or more characters are sent from the host to the guest via Windows Com/Serial, everything freezes.
Steps to reproduce:
1.
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Additional information:
I fix it in qemu/chardev/char-win.c see attached file