From cd672ca60f7c08a5189078c18579e12b65606f4c Mon Sep 17 00:00:00 2001
From: Mateusz Guzik <mjg@FreeBSD.org>
Date: Thu, 16 Jul 2015 14:30:11 +0000
Subject: [PATCH] Get rid of lim_update_thread and cred_update_thread.

Their primary use was in thread_cow_update to free up old resources.
Freeing had to be done with proc lock held and _cow_ funcs already knew
how to free old structs.
---
 sys/kern/init_main.c     |  5 ++++-
 sys/kern/kern_prot.c     | 18 ------------------
 sys/kern/kern_resource.c | 14 --------------
 sys/kern/kern_thread.c   | 24 ++++++++++++++++++------
 sys/sys/resourcevar.h    |  2 --
 sys/sys/ucred.h          |  1 -
 6 files changed, 22 insertions(+), 42 deletions(-)

diff --git a/sys/kern/init_main.c b/sys/kern/init_main.c
index 7552d517200f..a362d00fbfdf 100644
--- a/sys/kern/init_main.c
+++ b/sys/kern/init_main.c
@@ -827,6 +827,7 @@ static void
 create_init(const void *udata __unused)
 {
 	struct ucred *newcred, *oldcred;
+	struct thread *td;
 	int error;
 
 	error = fork1(&thread0, RFFDG | RFPROC | RFSTOPPED, 0, &initproc,
@@ -850,7 +851,9 @@ create_init(const void *udata __unused)
 	audit_cred_proc1(newcred);
 #endif
 	proc_set_cred(initproc, newcred);
-	cred_update_thread(FIRST_THREAD_IN_PROC(initproc));
+	td = FIRST_THREAD_IN_PROC(initproc);
+	crfree(td->td_ucred);
+	td->td_ucred = crhold(initproc->p_ucred);
 	PROC_UNLOCK(initproc);
 	sx_xunlock(&proctree_lock);
 	crfree(oldcred);
diff --git a/sys/kern/kern_prot.c b/sys/kern/kern_prot.c
index b531763b8b14..d7ec70134ddf 100644
--- a/sys/kern/kern_prot.c
+++ b/sys/kern/kern_prot.c
@@ -1934,24 +1934,6 @@ cru2x(struct ucred *cr, struct xucred *xcr)
 	    ngroups * sizeof(*cr->cr_groups));
 }
 
-/*
- * small routine to swap a thread's current ucred for the correct one taken
- * from the process.
- */
-void
-cred_update_thread(struct thread *td)
-{
-	struct proc *p;
-	struct ucred *cred;
-
-	p = td->td_proc;
-	cred = td->td_ucred;
-	PROC_LOCK_ASSERT(p, MA_OWNED);
-	td->td_ucred = crhold(p->p_ucred);
-	if (cred != NULL)
-		crfree(cred);
-}
-
 /*
  * Set initial process credentials.
  * Callers are responsible for providing the reference for provided credentials.
diff --git a/sys/kern/kern_resource.c b/sys/kern/kern_resource.c
index 48427637338f..b6dbab99188c 100644
--- a/sys/kern/kern_resource.c
+++ b/sys/kern/kern_resource.c
@@ -1436,17 +1436,3 @@ chgkqcnt(struct uidinfo *uip, int diff, rlim_t max)
 
 	return (chglimit(uip, &uip->ui_kqcnt, diff, max, "kqcnt"));
 }
-
-void
-lim_update_thread(struct thread *td)
-{
-	struct proc *p;
-	struct plimit *lim;
-
-	p = td->td_proc;
-	lim = td->td_limit;
-	PROC_LOCK_ASSERT(p, MA_OWNED);
-	td->td_limit = lim_hold(p->p_limit);
-	if (lim != NULL)
-		lim_free(lim);
-}
diff --git a/sys/kern/kern_thread.c b/sys/kern/kern_thread.c
index 0f65403f77fa..3c6232cc1e21 100644
--- a/sys/kern/kern_thread.c
+++ b/sys/kern/kern_thread.c
@@ -409,9 +409,9 @@ void
 thread_cow_free(struct thread *td)
 {
 
-	if (td->td_ucred)
+	if (td->td_ucred != NULL)
 		crfree(td->td_ucred);
-	if (td->td_limit)
+	if (td->td_limit != NULL)
 		lim_free(td->td_limit);
 }
 
@@ -419,15 +419,27 @@ void
 thread_cow_update(struct thread *td)
 {
 	struct proc *p;
+	struct ucred *oldcred;
+	struct plimit *oldlimit;
 
 	p = td->td_proc;
+	oldcred = NULL;
+	oldlimit = NULL;
 	PROC_LOCK(p);
-	if (td->td_ucred != p->p_ucred)
-		cred_update_thread(td);
-	if (td->td_limit != p->p_limit)
-		lim_update_thread(td);
+	if (td->td_ucred != p->p_ucred) {
+		oldcred = td->td_ucred;
+		td->td_ucred = crhold(p->p_ucred);
+	}
+	if (td->td_limit != p->p_limit) {
+		oldlimit = td->td_limit;
+		td->td_limit = lim_hold(p->p_limit);
+	}
 	td->td_cowgen = p->p_cowgen;
 	PROC_UNLOCK(p);
+	if (oldcred != NULL)
+		crfree(oldcred);
+	if (oldlimit != NULL)
+		lim_free(oldlimit);
 }
 
 /*
diff --git a/sys/sys/resourcevar.h b/sys/sys/resourcevar.h
index d374472c8269..9612f12aacea 100644
--- a/sys/sys/resourcevar.h
+++ b/sys/sys/resourcevar.h
@@ -159,7 +159,5 @@ void	 ui_racct_foreach(void (*callback)(struct racct *racct,
 	    void *arg2, void *arg3), void *arg2, void *arg3);
 #endif
 
-void	lim_update_thread(struct thread *td);
-
 #endif /* _KERNEL */
 #endif /* !_SYS_RESOURCEVAR_H_ */
diff --git a/sys/sys/ucred.h b/sys/sys/ucred.h
index 9a453087ff0e..d7e7fa5a947c 100644
--- a/sys/sys/ucred.h
+++ b/sys/sys/ucred.h
@@ -105,7 +105,6 @@ void	change_svuid(struct ucred *newcred, uid_t svuid);
 void	crcopy(struct ucred *dest, struct ucred *src);
 struct ucred	*crcopysafe(struct proc *p, struct ucred *cr);
 struct ucred	*crdup(struct ucred *cr);
-void	cred_update_thread(struct thread *td);
 void	proc_set_cred_init(struct proc *p, struct ucred *cr);
 struct ucred	*proc_set_cred(struct proc *p, struct ucred *cr);
 void	crfree(struct ucred *cr);