Change Details

Otherwise, per submitter report, if the PT_ATTACH SIGSTOP was delivered right after the thread was added to the sleepqueue but not yet really sleep, and cursig() caused debugger attach, the thread sleeps instead of returning to the userspace boundary with EINTR. PR: 231445

In particular, do not clear TDP_FSTP in ptracestop() if td_wchan is non-NULL. Leave it to sleepq_catch_signal() to clear and convert zero return code to EINTR. Otherwise, per submitter report, if the PT_ATTACH SIGSTOP was delivered right after the thread was added to the sleepqueue but not yet really sleep, and cursig() caused debugger attach, the thread sleeps instead of returning to the userspace boundary with EINTR. PR: 231445

In particular, do not clear TDP_FSTP in ptracestop() if td_wchan is non-NULL. Leave it to sleepq_catch_signal() to clear and convert zero return code to EINTR. Otherwise, per submitter report, if the PT_ATTACH SIGSTOP was delivered right after the thread was added to the sleepqueue but not yet really sleep, and cursig() caused debugger attach, the thread sleeps instead of returning to the userspace boundary with EINTR. PR: 231445