Hi guys, I spent some time investigating the sigqueue code path, which is used by realtime signals, but I am confused about some logics, please provide comments if you have specific knowledge about this part. I followed the call chain path of sigqueue, and pretty confident about how a signal is generated and put into a queue, but not sure how a signal is consumed. Followings are some details. When we used sigqueue, netbsd will invoke sys_sigqueueinfo->kill1->kpsignal2(assume we just want to send signal to a process)->sigput & sigpost.
Basically, sigput will put a signal into a queue specific to a process, and sigpost will change the running status of a process and notify proper process to handle the signal. In terms of consuming a signal, I saw there was function call sigclearall, which takes all signals from the queue and prepare to consume. I searched all related calls to sigclearall, it seems it is invoked when executing exec, exit functions. It seems not the correct callers to sigclearall when running a simple program like, https://github.com/ycui1984/posixtestsuite/blob/master/conformance/interfaces/sigqueue/9-1.cI guess there will be some routines that are called when a process is running on a processor. It may find the running flag is set with pending signals and then start to operate signals, but I cannot find the signal consumer code path. Any ideas on this? Thanks Charles
