svn commit: r266814 - head/sys/kern

[Don Lewis]

Author: truckman
Date: Wed May 28 16:57:17 2014
New Revision: 266814
URL: http://svnweb.freebsd.org/changeset/base/266814

Log:
  Initialize r_flags the same way in all cases using a sanitized copy of
  flags that has several bits cleared. The RF_WANTED and RF_FIRSTSHARE
  bits are invalid in this context, and we want to defer setting RF_ACTIVE
  in r_flags until later.  This should make rman_get_flags() return
  the correct answer in all cases.
  
  Add a KASSERT() to catch callers which incorrectly pass the RF_WANTED
  or RF_FIRSTSHARE flags.
  
  Do a strict equality check on the share type bits of flags.  In
  particular, do an equality check on RF_PREFETCHABLE.  The previous
  code would allow one type of mismatch of RF_PREFETCHABLE but disallow
  the other type of mismatch.  Also, ignore the the RF_ALIGNMENT_MASK
  bits since alignment validity should be handled by the amask check.
  This field contains an integer value, but previous code did a strange
  bitwise comparison on it.
  
  Leave the original value of flags unmolested as a minor debug aid.
  
  Change the start+amask overflow check to a KASSERT() since it is just
  meant to catch a highly unlikely programming error in the caller.
  
  Reviewed by:	jhb
  MFC after:	1 month

Modified:
  head/sys/kern/subr_rman.c

Modified: head/sys/kern/subr_rman.c
==============================================================================
--- head/sys/kern/subr_rman.c	Wed May 28 16:50:18 2014	(r266813)
+++ head/sys/kern/subr_rman.c	Wed May 28 16:57:17 2014	(r266814)
@@ -435,12 +435,14 @@ rman_adjust_resource(struct resource *rr
 	return (0);
 }
 
+#define	SHARE_TYPE(f)	(f & (RF_SHAREABLE | RF_TIMESHARE | RF_PREFETCHABLE))
+
 struct resource *
 rman_reserve_resource_bound(struct rman *rm, u_long start, u_long end,
 		      u_long count, u_long bound,  u_int flags,
 		      struct device *dev)
 {
-	u_int	want_activate;
+	u_int	new_rflags;
 	struct	resource_i *r, *s, *rv;
 	u_long	rstart, rend, amask, bmask;
 
@@ -450,8 +452,10 @@ rman_reserve_resource_bound(struct rman 
 	       "length %#lx, flags %u, device %s\n", rm->rm_descr, start, end,
 	       count, flags,
 	       dev == NULL ? "<null>" : device_get_nameunit(dev)));
-	want_activate = (flags & RF_ACTIVE);
-	flags &= ~RF_ACTIVE;
+	KASSERT((flags & (RF_WANTED | RF_FIRSTSHARE)) == 0,
+	    ("invalid flags %#x", flags));
+	new_rflags = (flags & ~(RF_ACTIVE | RF_WANTED | RF_FIRSTSHARE)) |
+	    RF_ALLOCATED;
 
 	mtx_lock(rm->rm_mtx);
 
@@ -466,10 +470,8 @@ rman_reserve_resource_bound(struct rman 
 	}
 
 	amask = (1ul << RF_ALIGNMENT(flags)) - 1;
-	if (start > ULONG_MAX - amask) {
-		DPRINTF(("start+amask would wrap around\n"));
-		goto out;
-	}
+	KASSERT(start <= ULONG_MAX - amask,
+	    ("start (%#lx) + amask (%#lx) would wrap around", start, amask));
 
 	/* If bound is 0, bmask will also be 0 */
 	bmask = ~(bound - 1);
@@ -522,7 +524,7 @@ rman_reserve_resource_bound(struct rman 
 			if ((s->r_end - s->r_start + 1) == count) {
 				DPRINTF(("candidate region is entire chunk\n"));
 				rv = s;
-				rv->r_flags |= RF_ALLOCATED | flags;
+				rv->r_flags = new_rflags;
 				rv->r_dev = dev;
 				goto out;
 			}
@@ -542,7 +544,7 @@ rman_reserve_resource_bound(struct rman 
 				goto out;
 			rv->r_start = rstart;
 			rv->r_end = rstart + count - 1;
-			rv->r_flags = flags | RF_ALLOCATED;
+			rv->r_flags = new_rflags;
 			rv->r_dev = dev;
 			rv->r_rm = rm;
 
@@ -603,7 +605,7 @@ rman_reserve_resource_bound(struct rman 
 		goto out;
 
 	for (s = r; s && s->r_end <= end; s = TAILQ_NEXT(s, r_link)) {
-		if ((s->r_flags & flags) == flags &&
+		if (SHARE_TYPE(s->r_flags) == SHARE_TYPE(flags) &&
 		    s->r_start >= start &&
 		    (s->r_end - s->r_start + 1) == count &&
 		    (s->r_start & amask) == 0 &&
@@ -613,8 +615,7 @@ rman_reserve_resource_bound(struct rman 
 				goto out;
 			rv->r_start = s->r_start;
 			rv->r_end = s->r_end;
-			rv->r_flags = s->r_flags &
-				(RF_ALLOCATED | RF_SHAREABLE | RF_TIMESHARE);
+			rv->r_flags = new_rflags;
 			rv->r_dev = dev;
 			rv->r_rm = rm;
 			if (s->r_sharehead == NULL) {
@@ -641,13 +642,12 @@ rman_reserve_resource_bound(struct rman 
 	 */
 out:
 	/*
-	 * If the user specified RF_ACTIVE in the initial flags,
-	 * which is reflected in `want_activate', we attempt to atomically
+	 * If the user specified RF_ACTIVE in flags, we attempt to atomically
 	 * activate the resource.  If this fails, we release the resource
 	 * and indicate overall failure.  (This behavior probably doesn't
 	 * make sense for RF_TIMESHARE-type resources.)
 	 */
-	if (rv && want_activate) {
+	if (rv && (flags & RF_ACTIVE) != 0) {
 		struct resource_i *whohas;
 		if (int_rman_activate_resource(rm, rv, &whohas)) {
 			int_rman_release_resource(rm, rv);