Locking for the per-process resource limits structure.

- struct plimit includes a mutex to protect a reference count.  The plimit
  structure is treated similarly to struct ucred in that is is always copy
  on write, so having a reference to a structure is sufficient to read from
  it without needing a further lock.
- The proc lock protects the p_limit pointer and must be held while reading
  limits from a process to keep the limit structure from changing out from
  under you while reading from it.
- Various global limits that are ints are not protected by a lock since
  int writes are atomic on all the archs we support and thus a lock
  wouldn't buy us anything.
- All accesses to individual resource limits from a process are abstracted
  behind a simple lim_rlimit(), lim_max(), and lim_cur() API that return
  either an rlimit, or the current or max individual limit of the specified
  resource from a process.
- dosetrlimit() was renamed to kern_setrlimit() to match existing style of
  other similar syscall helper functions.
- The alpha OSF/1 compat layer no longer calls getrlimit() and setrlimit()
  (it didn't used the stackgap when it should have) but uses lim_rlimit()
  and kern_setrlimit() instead.
- The svr4 compat no longer uses the stackgap for resource limits calls,
  but uses lim_rlimit() and kern_setrlimit() instead.
- The ibcs2 compat no longer uses the stackgap for resource limits.  It
  also no longer uses the stackgap for accessing sysctl's for the
  ibcs2_sysconf() syscall but uses kernel_sysctl() instead.  As a result,
  ibcs2_sysconf() no longer needs Giant.
- The p_rlimit macro no longer exists.

Submitted by:	mtm (mostly, I only did a few cleanups and catchups)
Tested on:	i386
Compiled on:	alpha, amd64

1 files changed, 24 insertions, 11 deletions

diff --git a/sys/vm/vm_mmap.c b/sys/vm/vm_mmap.c
index ab876a5..2cad29b 100644
--- a/sys/vm/vm_mmap.c
+++ b/sys/vm/vm_mmap.c
@@ -266,7 +266,7 @@ mmap(td, uap)
 			return (EINVAL);
 		if (addr + size < addr)
 			return (EINVAL);
-	}
+	} else {
 	/*
 	 * XXX for non-fixed mappings where no hint is provided or
 	 * the hint would fall in the potential heap space,
@@ -275,13 +275,15 @@ mmap(td, uap)
 	 * There should really be a pmap call to determine a reasonable
 	 * location.
 	 */
-	else if (addr == 0 ||
-	    (addr >= round_page((vm_offset_t)vms->vm_taddr) &&
-	     addr < round_page((vm_offset_t)vms->vm_daddr +
-	      td->td_proc->p_rlimit[RLIMIT_DATA].rlim_max)))
-		addr = round_page((vm_offset_t)vms->vm_daddr +
-		    td->td_proc->p_rlimit[RLIMIT_DATA].rlim_max);
-
+		PROC_LOCK(td->td_proc);
+		if (addr == 0 ||
+		    (addr >= round_page((vm_offset_t)vms->vm_taddr) &&
+		    addr < round_page((vm_offset_t)vms->vm_daddr +
+		    lim_max(td->td_proc, RLIMIT_DATA))))
+			addr = round_page((vm_offset_t)vms->vm_daddr +
+			    lim_max(td->td_proc, RLIMIT_DATA));
+		PROC_UNLOCK(td->td_proc);
+	}
 	mtx_lock(&Giant);	/* syscall marked mp-safe but isn't */
 	do {
 		if (flags & MAP_ANON) {
@@ -1002,9 +1004,13 @@ mlock(td, uap)
 		return (EAGAIN);
 
 #if 0
+	PROC_LOCK(td->td_proc);
 	if (size + ptoa(pmap_wired_count(vm_map_pmap(&td->td_proc->p_vmspace->vm_map))) >
-	    td->td_proc->p_rlimit[RLIMIT_MEMLOCK].rlim_cur)
+	    lim_cur(td->td_proc, RLIMIT_MEMLOCK)) {
+		PROC_UNLOCK(td->td_proc);
 		return (ENOMEM);
+	}
+	PROC_UNLOCK(td->td_proc);
 #else
 	error = suser(td);
 	if (error)
@@ -1044,9 +1050,13 @@ mlockall(td, uap)
 	 * If wiring all pages in the process would cause it to exceed
 	 * a hard resource limit, return ENOMEM.
 	 */
+	PROC_LOCK(td->td_proc);
 	if (map->size - ptoa(pmap_wired_count(vm_map_pmap(map)) >
-		td->td_proc->p_rlimit[RLIMIT_MEMLOCK].rlim_cur))
+		lim_cur(td->td_proc, RLIMIT_MEMLOCK))) {
+		PROC_UNLOCK(td->td_proc);
 		return (ENOMEM);
+	}
+	PROC_UNLOCK(td->td_proc);
 #else
 	error = suser(td);
 	if (error)
@@ -1176,10 +1186,13 @@ vm_mmap(vm_map_t map, vm_offset_t *addr, vm_size_t size, vm_prot_t prot,
 
 	objsize = size = round_page(size);
 
+	PROC_LOCK(td->td_proc);
 	if (td->td_proc->p_vmspace->vm_map.size + size >
-	    td->td_proc->p_rlimit[RLIMIT_VMEM].rlim_cur) {
+	    lim_cur(td->td_proc, RLIMIT_VMEM)) {
+		PROC_UNLOCK(td->td_proc);
 		return(ENOMEM);
 	}
+	PROC_UNLOCK(td->td_proc);
 
 	/*
 	 * We currently can only deal with page aligned file offsets.