- Move p_cpulimit to struct proc from struct plimit and protect it with

  sched_lock.  This means that we no longer access p_limit in mi_switch()
  and the p_limit pointer can be protected by the proc lock.
- Remove PRS_ZOMBIE check from CPU limit test in mi_switch().  PRS_ZOMBIE
  processes don't call mi_switch(), and even if they did there is no longer
  the danger of p_limit being NULL (which is what the original zombie check
  was added for).
- When we bump the current processes soft CPU limit in ast(), just bump the
  private p_cpulimit instead of the shared rlimit.  This fixes an XXX for
  some value of fix.  There is still a (probably benign) bug in that this
  code doesn't check that the new soft limit exceeds the hard limit.

Inspired by:	bde (2)

1 files changed, 2 insertions, 8 deletions

diff --git a/sys/kern/kern_synch.c b/sys/kern/kern_synch.c
index b0f9d92..29c3838 100644
--- a/sys/kern/kern_synch.c
+++ b/sys/kern/kern_synch.c
@@ -786,15 +786,9 @@ mi_switch(void)
 	/*
 	 * Check if the process exceeds its cpu resource allocation.  If
 	 * over max, arrange to kill the process in ast().
-	 *
-	 * XXX The checking for p_limit being NULL here is totally bogus,
-	 * but hides something easy to trip over, as a result of us switching
-	 * after the limit has been freed/set-to-NULL.  A KASSERT() will be
-	 * appropriate once this is no longer a bug, to watch for regression.
 	 */
-	if (p->p_state != PRS_ZOMBIE && p->p_limit != NULL &&
-	    p->p_limit->p_cpulimit != RLIM_INFINITY &&
-	    p->p_runtime.sec > p->p_limit->p_cpulimit) {
+	if (p->p_cpulimit != RLIM_INFINITY &&
+	    p->p_runtime.sec > p->p_cpulimit) {
 		p->p_sflag |= PS_XCPU;
 		ke->ke_flags |= KEF_ASTPENDING;
 	}