svn commit: r262260 - stable/10/sys/kern

[Mateusz Guzik]

Author: mjg
Date: Thu Feb 20 21:52:39 2014
New Revision: 262260
URL: http://svnweb.freebsd.org/changeset/base/262260

Log:
  MFC r259330,r259331:
  
  rlimit: add and utilize lim_shared
  
  rlimit: avoid unnecessary copying of rlimits
  
  If refcount is 1 just modify rlimits in place.

Modified:
  stable/10/sys/kern/kern_resource.c

Modified: stable/10/sys/kern/kern_resource.c
==============================================================================
--- stable/10/sys/kern/kern_resource.c  Thu Feb 20 21:36:05 2014        
(r262259)
+++ stable/10/sys/kern/kern_resource.c  Thu Feb 20 21:52:39 2014        
(r262260)
@@ -80,6 +80,8 @@ static int    donice(struct thread *td, str
 static struct uidinfo *uilookup(uid_t uid);
 static void    ruxagg_locked(struct rusage_ext *rux, struct thread *td);
 
+static __inline int    lim_shared(struct plimit *limp);
+
 /*
  * Resource controls and accounting.
  */
@@ -677,21 +679,29 @@ kern_proc_setrlimit(struct thread *td, s
                limp->rlim_max = RLIM_INFINITY;
 
        oldssiz.rlim_cur = 0;
-       newlim = lim_alloc();
+       newlim = NULL;
        PROC_LOCK(p);
+       if (lim_shared(p->p_limit)) {
+               PROC_UNLOCK(p);
+               newlim = lim_alloc();
+               PROC_LOCK(p);
+       }
        oldlim = p->p_limit;
        alimp = &oldlim->pl_rlimit[which];
        if (limp->rlim_cur > alimp->rlim_max ||
            limp->rlim_max > alimp->rlim_max)
                if ((error = priv_check(td, PRIV_PROC_SETRLIMIT))) {
                        PROC_UNLOCK(p);
-                       lim_free(newlim);
+                       if (newlim != NULL)
+                               lim_free(newlim);
                        return (error);
                }
        if (limp->rlim_cur > limp->rlim_max)
                limp->rlim_cur = limp->rlim_max;
-       lim_copy(newlim, oldlim);
-       alimp = &newlim->pl_rlimit[which];
+       if (newlim != NULL) {
+               lim_copy(newlim, oldlim);
+               alimp = &newlim->pl_rlimit[which];
+       }
 
        switch (which) {
 
@@ -741,9 +751,11 @@ kern_proc_setrlimit(struct thread *td, s
        if (p->p_sysent->sv_fixlimit != NULL)
                p->p_sysent->sv_fixlimit(limp, which);
        *alimp = *limp;
-       p->p_limit = newlim;
+       if (newlim != NULL)
+               p->p_limit = newlim;
        PROC_UNLOCK(p);
-       lim_free(oldlim);
+       if (newlim != NULL)
+               lim_free(oldlim);
 
        if (which == RLIMIT_STACK) {
                /*
@@ -1129,6 +1141,14 @@ lim_hold(limp)
        return (limp);
 }
 
+static __inline int
+lim_shared(limp)
+       struct plimit *limp;
+{
+
+       return (limp->pl_refcnt > 1);
+}
+
 void
 lim_fork(struct proc *p1, struct proc *p2)
 {
@@ -1162,7 +1182,7 @@ lim_copy(dst, src)
        struct plimit *dst, *src;
 {
 
-       KASSERT(dst->pl_refcnt == 1, ("lim_copy to shared limit"));
+       KASSERT(!lim_shared(dst), ("lim_copy to shared limit"));
        bcopy(src->pl_rlimit, dst->pl_rlimit, sizeof(src->pl_rlimit));
 }
 
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