Extend the support for exempting processes from being killed when swap is

exhausted.
- Add a new protect(1) command that can be used to set or revoke protection
  from arbitrary processes.  Similar to ktrace it can apply a change to all
  existing descendants of a process as well as future descendants.
- Add a new procctl(2) system call that provides a generic interface for
  control operations on processes (as opposed to the debugger-specific
  operations provided by ptrace(2)).  procctl(2) uses a combination of
  idtype_t and an id to identify the set of processes on which to operate
  similar to wait6().
- Add a PROC_SPROTECT control operation to manage the protection status
  of a set of processes.  MADV_PROTECT still works for backwards
  compatability.
- Add a p_flag2 to struct proc (and a corresponding ki_flag2 to kinfo_proc)
  the first bit of which is used to track if P_PROTECT should be inherited
  by new child processes.

Reviewed by:	kib, jilles (earlier version)
Approved by:	re (delphij)
MFC after:	1 month

1 files changed, 4 insertions, 4 deletions

diff --git a/sys/sys/proc.h b/sys/sys/proc.h
index 2f03152..5443b61 100644
--- a/sys/sys/proc.h
+++ b/sys/sys/proc.h
@@ -492,11 +492,8 @@ struct proc {
 	struct callout	p_limco;	/* (c) Limit callout handle */
 	struct sigacts	*p_sigacts;	/* (x) Signal actions, state (CPU). */
 
-	/*
-	 * The following don't make too much sense.
-	 * See the td_ or ke_ versions of the same flags.
-	 */
 	int		p_flag;		/* (c) P_* flags. */
+	int		p_flag2;	/* (c) P2_* flags. */
 	enum {
 		PRS_NEW = 0,		/* In creation */
 		PRS_NORMAL,		/* threads can be run. */
@@ -641,6 +638,9 @@ struct proc {
 #define	P_SHOULDSTOP(p)	((p)->p_flag & P_STOPPED)
 #define	P_KILLED(p)	((p)->p_flag & P_WKILLED)
 
+/* These flags are kept in p_flag2. */
+#define	P2_INHERIT_PROTECTED 0x00000001 /* New children get P_PROTECTED. */
+
 /*
  * These were process status values (p_stat), now they are only used in
  * legacy conversion code.