minix/kernel/system/do_nice.c
Tomas Hruby c6fec6866f No locking in kernel code
- No locking in RTS_(UN)SET macros

- No lock_notify()

- Removed unused lock_send()

- No lock/unlock macros anymore
2010-02-09 15:26:58 +00:00

49 lines
1.5 KiB
C

/* The kernel call implemented in this file:
* m_type: SYS_NICE
*
* The parameters for this kernel call are:
* m1_i1: PR_ENDPT process number to change priority
* m1_i2: PR_PRIORITY the new priority
*/
#include "../system.h"
#include <sys/resource.h>
#if USE_NICE
/*===========================================================================*
* do_nice *
*===========================================================================*/
PUBLIC int do_nice(struct proc * caller, message * m_ptr)
{
/* Change process priority or stop the process. */
int proc_nr, pri, new_q ;
register struct proc *rp;
/* Extract the message parameters and do sanity checking. */
if(!isokendpt(m_ptr->PR_ENDPT, &proc_nr)) return EINVAL;
if (iskerneln(proc_nr)) return(EPERM);
pri = m_ptr->PR_PRIORITY;
rp = proc_addr(proc_nr);
/* The value passed in is currently between PRIO_MIN and PRIO_MAX.
* We have to scale this between MIN_USER_Q and MAX_USER_Q to match
* the kernel's scheduling queues.
*/
if (pri < PRIO_MIN || pri > PRIO_MAX) return(EINVAL);
new_q = MAX_USER_Q + (pri-PRIO_MIN) * (MIN_USER_Q-MAX_USER_Q+1) /
(PRIO_MAX-PRIO_MIN+1);
if (new_q < MAX_USER_Q) new_q = MAX_USER_Q; /* shouldn't happen */
if (new_q > MIN_USER_Q) new_q = MIN_USER_Q; /* shouldn't happen */
/* Dequeue the process and put it in its new queue if it is runnable. */
RTS_SET(rp, RTS_SYS_LOCK);
rp->p_max_priority = rp->p_priority = new_q;
RTS_UNSET(rp, RTS_SYS_LOCK);
return(OK);
}
#endif /* USE_NICE */