Name
sys_tgkill — 
     send signal to one specific thread
 
Synopsis
| long sys_tgkill ( | pid_t tgid, | 
|  | pid_t 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.