Extend the rman(9) API to support altering an existing resource.

Specifically, these changes allow a resource to back a relocatable and
resizable resource such as the I/O window decoders in PCI-PCI bridges.
- rman_adjust_resource() can adjust the start and end address of an
  existing resource.  It only succeeds if the newly requested address
  space is already free.  It also supports shrinking a resource in
  which case the freed space will be marked unallocated in the rman.
- rman_first_free_region() and rman_last_free_region() return the
  start and end addresses for the first or last unallocated region in
  an rman, respectively.  This can be used to determine by how much
  the resource backing an rman must be adjusted to accomodate an
  allocation request that does not fit into the existing rman.

While here, document the rm_start and rm_end fields in struct rman,
rman_is_region_manager(), the bound argument to
rman_reserve_resource_bound(), and rman_init_from_resource().

share/man/man9/Makefile

@@ -967,9 +967,11 @@ MLINKS+=refcount.9 refcount_acquire.9 \
 MLINKS+=resource_int_value.9 resource_long_value.9 \
 	resource_int_value.9 resource_string_value.9
 MLINKS+=rman.9 rman_activate_resource.9 \
+	rman.9 rman_adjust_resource.9 \
 	rman.9 rman_await_resource.9 \
 	rman.9 rman_deactivate_resource.9 \
 	rman.9 rman_fini.9 \
+	rman.9 rman_first_free_region.9 \
 	rman.9 rman_get_bushandle.9 \
 	rman.9 rman_get_bustag.9 \
 	rman.9 rman_get_device.9 \
@@ -980,6 +982,9 @@ MLINKS+=rman.9 rman_activate_resource.9 \
 	rman.9 rman_get_start.9 \
 	rman.9 rman_get_virtual.9 \
 	rman.9 rman_init.9 \
+	rman.9 rman_init_from_resource.9 \
+	rman.9 rman_is_region_manager.9 \
+	rman.9 rman_last_free_region.9 \
 	rman.9 rman_make_alignment_flags.9 \
 	rman.9 rman_manage_region.9 \
 	rman.9 rman_release_resource.9 \

share/man/man9/rman.9

@@ -25,17 +25,22 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd April 29, 2007
+.Dd April 29, 2011
 .Dt RMAN 9
 .Os
 .Sh NAME
 .Nm rman ,
 .Nm rman_activate_resource ,
+.Nm rman_adjust_resource ,
 .Nm rman_await_resource ,
 .Nm rman_deactivate_resource ,
 .Nm rman_fini ,
 .Nm rman_init ,
+.Nm rman_init_from_resource ,
+.Nm rman_is_region_manager ,
 .Nm rman_manage_region ,
+.Nm rman_first_free_region ,
+.Nm rman_last_free_region ,
 .Nm rman_release_resource ,
 .Nm rman_reserve_resource ,
 .Nm rman_reserve_resource_bound ,
@@ -60,6 +65,8 @@
 .Ft int
 .Fn rman_activate_resource "struct resource *r"
 .Ft int
+.Fn rman_adjust_resource "struct resource *r" "u_long start" "u_long end"
+.Ft int
 .Fn rman_await_resource "struct resource *r" "int pri2" "int timo"
 .Ft int
 .Fn rman_deactivate_resource "struct resource *r"
@@ -68,8 +75,16 @@
 .Ft int
 .Fn rman_init "struct rman *rm"
 .Ft int
+.Fn rman_init_from_resource "struct rman *rm" "struct resource *r"
+.Ft int
+.Fn rman_is_region_manager "struct resource *r" "struct rman *rm"
+.Ft int
 .Fn rman_manage_region "struct rman *rm" "u_long start" "u_long end"
 .Ft int
+.Fn rman_first_free_region "struct rman *rm" "u_long *start" "u_long *end"
+.Ft int
+.Fn rman_last_free_region "struct rman *rm" "u_long *start" "u_long *end"
+.Ft int
 .Fn rman_release_resource "struct resource *r"
 .Ft "struct resource *"
 .Fo rman_reserve_resource
@@ -155,6 +170,14 @@ shall be set to
 The field
 .Va rm_descr
 shall be set to a string that describes the resource to be managed.
+The
+.Va rm_start
+and
+.Va rm_end
+fields may be set to limit the range of acceptable resource addresses.
+If these fields are not set,
+.Fn rman_init
+will initialize them to allow the entire range of resource addresses.
 It also initializes any mutexes associated with the structure.
 If
 .Fn rman_init
@@ -194,12 +217,49 @@ If successful,
 will return 0.
 If the region overlaps with an existing region, it will return
 .Er EBUSY .
+If any part of the region falls outside of the valid address range for
+.Fa rm ,
+it will return
+.Er EINVAL .
 .Er ENOMEM
-will be return when
+will be returned when
 .Fn rman_manage_region
 failed to allocate memory for the region.
 .Pp
 The
+.Fn rman_init_from_resource
+function is a wrapper routine to create a resource manager backed by an
+existing resource.
+It initializes
+.Fa rm
+using
+.Fn rman_init
+and then adds a region to
+.Fa rm
+corresponding to the address range allocated to
+.Fa r
+via
+.Fn rman_manage_region .
+.Pp
+The
+.Fn rman_first_free_region
+and
+.Fn rman_last_free_region
+functions can be used to query a resource manager for its first
+.Pq or last
+unallocated region.
+If
+.Fa rm
+contains no free region,
+these functions will return
+.Er ENOENT .
+Otherwise,
+.Fa *start
+and
+.Fa *end
+are set to the bounds of the free region and zero is returned.
+.Pp
+The
 .Fn rman_reserve_resource_bound
 function is where the bulk of the
 .Nm
@@ -212,8 +272,9 @@ The caller can specify the
 .Fa start
 and
 .Fa end
-of an acceptable range, as well as
-alignment, and the code will attempt to find a free segment which fits.
+of an acceptable range,
+as well as a boundary restriction and required aligment,
+and the code will attempt to find a free segment which fits.
 The
 .Fa start
 argument is the lowest acceptable starting value of the resource.
@@ -225,6 +286,19 @@ Therefore,
 must be \[<=]
 .Fa end
 for any allocation to happen.
+The aligment requirement
+.Pq if any
+is specified in
+.Fa flags .
+The
+.Fa bound
+argument may be set to specify a boundary restriction such that an
+allocated region may cross an address that is a multiple of the
+boundary.
+The
+.Fa bound
+argument must be a power of two.
+It may be set to zero to specify no boundary restriction.
 The default behavior is to allocate an exclusive segment, unless the
 .Dv RF_SHAREABLE
 or
@@ -240,7 +314,7 @@ function is used to reserve resources within a previously established region.
 It is a simplified interface to
 .Fn rman_reserve_resource_bound
 which passes 0 for the
-.Fa flags
+.Fa bound
 argument.
 .Pp
 The
@@ -251,6 +325,49 @@ This should be used when calling
 .Fn rman_reserve_resource_bound .
 .Pp
 The
+.Fn rman_is_region_manager
+function returns true if the allocated resource
+.Fa r
+was allocated from
+.Fa rm .
+Otherwise,
+it returns false.
+.Pp
+The
+.Fn rman_adjust_resource
+function is used to adjust the reserved address range of an allocated resource
+to reserve
+.Fa start
+through
+.Fa end .
+It can be used to grow or shrink one or both ends of the resource range.
+The current implementation does not support entirely relocating the resource
+and will fail with
+.Er EINVAL
+if the new resource range does not overlap the old resource range.
+If either end of the resource range grows and the new resource range would
+conflict with another allocated resource,
+the function will fail with
+.Er EBUSY .
+The
+.Fn rman_adjust_resource
+function does not support adjusting the resource range for shared resources
+and will fail such attempts with
+.Er EINVAL .
+Upon success,
+the resource
+.Fa r
+will have a start address of
+.Fa start
+and an end address of
+.Fa end
+and the function will return zero.
+Note that none of the constraints of the original allocation request such
+as alignment or boundary restrictions are checked by
+.Fn rman_adjust_resource .
+It is the caller's responsibility to enforce any such requirements.
+.Pp
+The
 .Fn rman_release_resource
 function releases the reserved resource
 .Fa r .

sys/kern/subr_rman.c

@@ -272,6 +272,164 @@ rman_fini(struct rman *rm)
 	return 0;
 }
 
+int
+rman_first_free_region(struct rman *rm, u_long *start, u_long *end)
+{
+	struct resource_i *r;
+
+	mtx_lock(rm->rm_mtx);
+	TAILQ_FOREACH(r, &rm->rm_list, r_link) {
+		if (!(r->r_flags & RF_ALLOCATED)) {
+			*start = r->r_start;
+			*end = r->r_end;
+			mtx_unlock(rm->rm_mtx);
+			return (0);
+		}
+	}
+	mtx_unlock(rm->rm_mtx);
+	return (ENOENT);
+}
+
+int
+rman_last_free_region(struct rman *rm, u_long *start, u_long *end)
+{
+	struct resource_i *r;
+
+	mtx_lock(rm->rm_mtx);
+	TAILQ_FOREACH_REVERSE(r, &rm->rm_list, resource_head, r_link) {
+		if (!(r->r_flags & RF_ALLOCATED)) {
+			*start = r->r_start;
+			*end = r->r_end;
+			mtx_unlock(rm->rm_mtx);
+			return (0);
+		}
+	}
+	mtx_unlock(rm->rm_mtx);
+	return (ENOENT);
+}
+
+/* Shrink or extend one or both ends of an allocated resource. */
+int
+rman_adjust_resource(struct resource *rr, u_long start, u_long end)
+{
+	struct	resource_i *r, *s, *t, *new;
+	struct	rman *rm;
+
+	/* Not supported for shared resources. */
+	r = rr->__r_i;
+	if (r->r_flags & (RF_TIMESHARE | RF_SHAREABLE))
+		return (EINVAL);
+
+	/*
+	 * This does not support wholesale moving of a resource.  At
+	 * least part of the desired new range must overlap with the
+	 * existing resource.
+	 */
+	if (end < r->r_start || r->r_end < start)
+		return (EINVAL);
+
+	/*
+	 * Find the two resource regions immediately adjacent to the
+	 * allocated resource.
+	 */
+	rm = r->r_rm;
+	mtx_lock(rm->rm_mtx);
+#ifdef INVARIANTS
+	TAILQ_FOREACH(s, &rm->rm_list, r_link) {
+		if (s == r)
+			break;
+	}
+	if (s == NULL)
+		panic("resource not in list");
+#endif
+	s = TAILQ_PREV(r, resource_head, r_link);
+	t = TAILQ_NEXT(r, r_link);
+	KASSERT(s == NULL || s->r_end + 1 == r->r_start,
+	    ("prev resource mismatch"));
+	KASSERT(t == NULL || r->r_end + 1 == t->r_start,
+	    ("next resource mismatch"));
+
+	/*
+	 * See if the changes are permitted.  Shrinking is always allowed,
+	 * but growing requires sufficient room in the adjacent region.
+	 */
+	if (start < r->r_start && (s == NULL || (s->r_flags & RF_ALLOCATED) ||
+	    s->r_start > start)) {
+		mtx_unlock(rm->rm_mtx);
+		return (EBUSY);
+	}
+	if (end > r->r_end && (t == NULL || (t->r_flags & RF_ALLOCATED) ||
+	    t->r_end < end)) {
+		mtx_unlock(rm->rm_mtx);
+		return (EBUSY);
+	}
+
+	/*
+	 * While holding the lock, grow either end of the resource as
+	 * needed and shrink either end if the shrinking does not require
+	 * allocating a new resource.  We can safely drop the lock and then
+	 * insert a new range to handle the shrinking case afterwards.
+	 */
+	if (start < r->r_start ||
+	    (start > r->r_start && s != NULL && !(s->r_flags & RF_ALLOCATED))) {
+		KASSERT(s->r_flags == 0, ("prev is busy"));
+		r->r_start = start;
+		if (s->r_start == start) {
+			TAILQ_REMOVE(&rm->rm_list, s, r_link);
+			free(s, M_RMAN);
+		} else
+			s->r_end = start - 1;
+	}
+	if (end > r->r_end ||
+	    (end < r->r_end && t != NULL && !(t->r_flags & RF_ALLOCATED))) {
+		KASSERT(t->r_flags == 0, ("next is busy"));
+		r->r_end = end;
+		if (t->r_end == end) {
+			TAILQ_REMOVE(&rm->rm_list, t, r_link);
+			free(t, M_RMAN);
+		} else
+			t->r_start = end + 1;
+	}
+	mtx_unlock(rm->rm_mtx);
+
+	/*
+	 * Handle the shrinking cases that require allocating a new
+	 * resource to hold the newly-free region.  We have to recheck
+	 * if we still need this new region after acquiring the lock.
+	 */
+	if (start > r->r_start) {
+		new = int_alloc_resource(M_WAITOK);
+		new->r_start = r->r_start;
+		new->r_end = start - 1;
+		new->r_rm = rm;
+		mtx_lock(rm->rm_mtx);
+		r->r_start = start;
+		s = TAILQ_PREV(r, resource_head, r_link);
+		if (s != NULL && !(s->r_flags & RF_ALLOCATED)) {
+			s->r_end = start - 1;
+			free(new, M_RMAN);
+		} else
+			TAILQ_INSERT_BEFORE(r, new, r_link);
+		mtx_unlock(rm->rm_mtx);
+	}
+	if (end < r->r_end) {
+		new = int_alloc_resource(M_WAITOK);
+		new->r_start = end + 1;
+		new->r_end = r->r_end;
+		new->r_rm = rm;
+		mtx_lock(rm->rm_mtx);
+		r->r_end = end;
+		t = TAILQ_NEXT(r, r_link);
+		if (t != NULL && !(t->r_flags & RF_ALLOCATED)) {
+			t->r_start = end + 1;
+			free(new, M_RMAN);
+		} else
+			TAILQ_INSERT_AFTER(&rm->rm_list, r, new, r_link);
+		mtx_unlock(rm->rm_mtx);
+	}
+	return (0);
+}
+
 struct resource *
 rman_reserve_resource_bound(struct rman *rm, u_long start, u_long end,
 		      u_long count, u_long bound,  u_int flags,

sys/sys/rman.h

@@ -116,7 +116,9 @@ struct rman {
 TAILQ_HEAD(rman_head, rman);
 
 int	rman_activate_resource(struct resource *r);
+int	rman_adjust_resource(struct resource *r, u_long start, u_long end);
 int	rman_await_resource(struct resource *r, int pri, int timo);
+int	rman_first_free_region(struct rman *rm, u_long *start, u_long *end);
 bus_space_handle_t rman_get_bushandle(struct resource *);
 bus_space_tag_t rman_get_bustag(struct resource *);
 u_long	rman_get_end(struct resource *);
@@ -130,6 +132,7 @@ int	rman_deactivate_resource(struct resource *r);
 int	rman_fini(struct rman *rm);
 int	rman_init(struct rman *rm);
 int	rman_init_from_resource(struct rman *rm, struct resource *r);
+int	rman_last_free_region(struct rman *rm, u_long *start, u_long *end);
 uint32_t rman_make_alignment_flags(uint32_t size);
 int	rman_manage_region(struct rman *rm, u_long start, u_long end);
 int	rman_is_region_manager(struct resource *r, struct rman *rm);