NAME
sys_tgkill - send signal to one specific thread
SYNOPSIS
long sys_tgkill (int tgid, int pid, int sig);
ARGUMENTS
tgid the thread group ID of the thread
pid the PID of the thread
sig signal to be sent
DESCRIPTION
This syscall also checks the tgid and returns -ESRCH even if the PID
exists but it’s not belonging to the target process anymore. This
method solves the problem of threads exiting and PIDs getting reused.