Invoking a signal handler

[Shrivats]

Hi,


I am trying to understand how the kernel invokes the signal handler for a process, to deliver an asynchronous signal posted by another process.


I was looking at the sendsig() function which saves the current user context. My question is, when and how does the transition from the kernel mode to the user mode take place so that the signal handler is invoked? 




Thanks,
-shrivatsan