poll: Write back only revents to userspace, matching Linux behavior#12898
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copybara-service[bot] merged 2 commits intomasterfrom Apr 9, 2026
Merged
poll: Write back only revents to userspace, matching Linux behavior#12898copybara-service[bot] merged 2 commits intomasterfrom
copybara-service[bot] merged 2 commits intomasterfrom
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doPoll() was modifying pfd.Events (adding POLLHUP|POLLERR) and writing back the entire pollfd struct. Linux only writes back revents via unsafe_put_user() in do_sys_poll(). The polluted events field broke libevent's poll_del(), causing a busy-loop in tmux (CPU 96.6%). Fix: write back only the 2-byte revents field per fd in doPoll(). Signed-off-by: Tan Yifeng <yiftan@tencent.com>
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poll: Write back only revents to userspace, matching Linux behavior
doPoll() was modifying pfd.Events (adding POLLHUP|POLLERR) and writing back the entire pollfd struct. Linux only writes back revents via unsafe_put_user() in do_sys_poll(). The polluted events field broke libevent's poll_del(), causing a busy-loop in tmux (CPU 96.6%).
Fix: write back only the 2-byte revents field per fd in doPoll().
FUTURE_COPYBARA_INTEGRATE_REVIEW=#12851 from tanyifeng:poll-revents-writeback 3169ea6