send_sig_info() question: Missing signal?

qinqin · 03-27-2012, 01:28 AM

Hi all,

I am writing a driver which sends signal from kernel to user space process.

I am using send_sig_info() from kernel and I am using real time signal (e.g., signal number = SIGRTMIN+2). In user space, I am using sigaction() to register the signal handler to this signal.

The issue I am seeing right now is that sometimes (randomly) even send_sig_info() returns successfully, my user space signal handler is not being called.

Could you please give some hints what could be the issue?

nini09 · 03-27-2012, 03:10 PM

You can't assume real-time signal is no lost in Linux domain. The real-time signal can sometime be lost. If the signal deliver so quickly and application doesn't handle them, the signal could be ignored.

qinqin · 03-27-2012, 04:38 PM

Quote:

Originally Posted by nini09

You can't assume real-time signal is no lost in Linux domain. The real-time signal can sometime be lost. If the signal deliver so quickly and application doesn't handle them, the signal could be ignored.

Thanks for the reply. Could you please be more specific on "If the signal deliver so quickly and application doesn't handle them, the signal could be ignored". Do you mean the queue for RT signal is full and signal is dropped? Is there way to check the status of the queue?

nini09 · 03-28-2012, 02:35 PM

When queue is full, it doesn't always return error code. Only special signal return error code.