final ucred patch

[Julian Elischer]

After comments by jhb and bde

-- 
+------------------------------------+       ______ _  __
|   __--_|\  Julian Elischer         |       \     U \/ / hard at work in 
|  /       \ [EMAIL PROTECTED]     +------>x   USA    \ a very strange
| (   OZ    )                                \___   ___ | country !
+- X_.---._/    presently in San Francisco       \_/   \\
          v

? i386/conf/LINT
Index: i386/i386/trap.c
===================================================================
RCS file: /home/ncvs/src/sys/i386/i386/trap.c,v
retrieving revision 1.211
diff -u -r1.211 trap.c
--- i386/i386/trap.c    10 Jan 2002 11:49:54 -0000      1.211
+++ i386/i386/trap.c    10 Feb 2002 00:52:58 -0000
@@ -256,9 +256,19 @@
                sticks = td->td_kse->ke_sticks;
                td->td_frame = &frame;
                KASSERT(td->td_ucred == NULL, ("already have a ucred"));
-               PROC_LOCK(p);
-               td->td_ucred = crhold(p->p_ucred);
-               PROC_UNLOCK(p);
+               if (td->td_ucred != p->p_ucred) {
+                       if (td->td_ucred) {
+                               mtx_lock(&Giant);
+                               crfree(td->td_ucred);
+                               td->td_ucred = NULL;
+                               mtx_unlock(&Giant);
+                       }
+                       if (p->p_ucred) {
+                               PROC_LOCK(p);
+                               td->td_ucred = crhold(p->p_ucred);
+                               PROC_UNLOCK(p);
+                       }
+               }
 
                switch (type) {
                case T_PRIVINFLT:       /* privileged instruction fault */
@@ -644,10 +654,12 @@
        userret(td, &frame, sticks);
        mtx_assert(&Giant, MA_NOTOWNED);
 userout:
+#ifdef INVARIANTS
        mtx_lock(&Giant);
        crfree(td->td_ucred);
-       mtx_unlock(&Giant);
        td->td_ucred = NULL;
+       mtx_unlock(&Giant);
+#endif
 out:
        return;
 }
@@ -954,9 +966,19 @@
        sticks = td->td_kse->ke_sticks;
        td->td_frame = &frame;
        KASSERT(td->td_ucred == NULL, ("already have a ucred"));
-       PROC_LOCK(p);
-       td->td_ucred = crhold(p->p_ucred);
-       PROC_UNLOCK(p);
+       if (td->td_ucred != p->p_ucred) {
+               if (td->td_ucred) {
+                       mtx_lock(&Giant);
+                       crfree(td->td_ucred);
+                       td->td_ucred = NULL;
+                       mtx_unlock(&Giant);
+               }
+               if (p->p_ucred) {
+                       PROC_LOCK(p);
+                       td->td_ucred = crhold(p->p_ucred);
+                       PROC_UNLOCK(p);
+               }
+       }
        params = (caddr_t)frame.tf_esp + sizeof(int);
        code = frame.tf_eax;
        orig_tf_eflags = frame.tf_eflags;
@@ -1099,10 +1121,14 @@
         */
        STOPEVENT(p, S_SCX, code);
 
-       mtx_lock(&Giant);
-       crfree(td->td_ucred);
-       mtx_unlock(&Giant);
-       td->td_ucred = NULL;
+#ifdef INVARIANTS
+       if (td->td_ucred) {
+               mtx_lock(&Giant);
+               crfree(td->td_ucred);
+               td->td_ucred = NULL;
+               mtx_unlock(&Giant);
+       }
+#endif
 #ifdef WITNESS
        if (witness_list(td)) {
                panic("system call %s returning with mutex(s) held\n",
Index: kern/subr_trap.c
===================================================================
RCS file: /home/ncvs/src/sys/kern/subr_trap.c,v
retrieving revision 1.206
diff -u -r1.206 subr_trap.c
--- kern/subr_trap.c    17 Jan 2002 17:49:23 -0000      1.206
+++ kern/subr_trap.c    10 Feb 2002 00:53:00 -0000
@@ -161,9 +161,19 @@
                        p->p_stats->p_prof.pr_ticks = 0;
                }
                mtx_unlock_spin(&sched_lock);
-               PROC_LOCK(p);
-               td->td_ucred = crhold(p->p_ucred);
-               PROC_UNLOCK(p);
+               if (td->td_ucred != p->p_ucred) {
+                       if (td->td_ucred) {
+                               mtx_lock(&Giant);
+                               crfree(td->td_ucred);
+                               td->td_ucred = NULL;
+                               mtx_unlock(&Giant);
+                       }
+                       if (p->p_ucred) {
+                               PROC_LOCK(p);
+                               td->td_ucred = crhold(p->p_ucred);
+                               PROC_UNLOCK(p);
+                       }
+               }
                if (flags & KEF_OWEUPC && sflag & PS_PROFIL)
                        addupc_task(ke, p->p_stats->p_prof.pr_addr, prticks);
                if (sflag & PS_ALRMPEND) {
@@ -188,10 +198,14 @@
                }
 
                userret(td, framep, sticks);
-               mtx_lock(&Giant);
-               crfree(td->td_ucred);
-               mtx_unlock(&Giant);
-               td->td_ucred = NULL;
+#ifdef INVARIANTS
+               if (td->td_ucred) {
+                       mtx_lock(&Giant);
+                       crfree(td->td_ucred);
+                       td->td_ucred = NULL;
+                       mtx_unlock(&Giant);
+               }
+#endif
                s = cpu_critical_enter();
        }
        mtx_assert(&Giant, MA_NOTOWNED);