minix3/kernel/system/do_runctl.c

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2020-02-21 00:59:27 +05:30
/* The kernel call implemented in this file:
* m_type: SYS_RUNCTL
*
* The parameters for this kernel call are:
* m1_i1: RC_ENDPT process number to control
* m1_i2: RC_ACTION stop or resume the process
* m1_i3: RC_FLAGS request flags
*/
#include "kernel/system.h"
#include <assert.h>
#if USE_RUNCTL
/*===========================================================================*
* do_runctl *
*===========================================================================*/
int do_runctl(struct proc * caller, message * m_ptr)
{
/* Control a process's RTS_PROC_STOP flag. Used for process management.
* If the process is queued sending a message or stopped for system call
* tracing, and the RC_DELAY request flag is given, set MF_SIG_DELAY instead
* of RTS_PROC_STOP, and send a SIGSNDELAY signal later when the process is done
* sending (ending the delay). Used by PM for safe signal delivery.
*/
int proc_nr, action, flags;
register struct proc *rp;
/* Extract the message parameters and do sanity checking. */
if (!isokendpt(m_ptr->RC_ENDPT, &proc_nr)) return(EINVAL);
if (iskerneln(proc_nr)) return(EPERM);
rp = proc_addr(proc_nr);
action = m_ptr->RC_ACTION;
flags = m_ptr->RC_FLAGS;
/* Is the target sending or syscall-traced? Then set MF_SIG_DELAY instead.
* Do this only when the RC_DELAY flag is set in the request flags field.
* The process will not become runnable before PM has called SYS_ENDKSIG.
* Note that asynchronous messages are not covered: a process using SENDA
* should not also install signal handlers *and* expect POSIX compliance.
*/
if (action == RC_STOP && (flags & RC_DELAY)) {
if (RTS_ISSET(rp, RTS_SENDING) || (rp->p_misc_flags & MF_SC_DEFER))
rp->p_misc_flags |= MF_SIG_DELAY;
if (rp->p_misc_flags & MF_SIG_DELAY)
return (EBUSY);
}
/* Either set or clear the stop flag. */
switch (action) {
case RC_STOP:
#if CONFIG_SMP
/* check if we must stop a process on a different CPU */
if (rp->p_cpu != cpuid) {
smp_schedule_stop_proc(rp);
break;
}
#endif
RTS_SET(rp, RTS_PROC_STOP);
break;
case RC_RESUME:
assert(RTS_ISSET(rp, RTS_PROC_STOP));
RTS_UNSET(rp, RTS_PROC_STOP);
break;
default:
return(EINVAL);
}
return(OK);
}
#endif /* USE_RUNCTL */