PNP: replace pnp_resource_table with dynamically allocated resources

PNP used to have a fixed-size pnp_resource_table for tracking the
resources used by a device.  This table often overflowed, so we've
had to increase the table size, which wastes memory because most
devices have very few resources.

This patch replaces the table with a linked list of resources where
the entries are allocated on demand.

This removes messages like these:

    pnpacpi: exceeded the max number of IO resources
    00:01: too many I/O port resources

References:

    http://bugzilla.kernel.org/show_bug.cgi?id=9535
    http://bugzilla.kernel.org/show_bug.cgi?id=9740
    http://lkml.org/lkml/2007/11/30/110

This patch also changes the way PNP uses the IORESOURCE_UNSET,
IORESOURCE_AUTO, and IORESOURCE_DISABLED flags.

Prior to this patch, the pnp_resource_table entries used the flags
like this:

    IORESOURCE_UNSET
	This table entry is unused and available for use.  When this flag
	is set, we shouldn't look at anything else in the resource structure.
	This flag is set when a resource table entry is initialized.

    IORESOURCE_AUTO
	This resource was assigned automatically by pnp_assign_{io,mem,etc}().

	This flag is set when a resource table entry is initialized and
	cleared whenever we discover a resource setting by reading an ISAPNP
	config register, parsing a PNPBIOS resource data stream, parsing an
	ACPI _CRS list, or interpreting a sysfs "set" command.

	Resources marked IORESOURCE_AUTO are reinitialized and marked as
	IORESOURCE_UNSET by pnp_clean_resource_table() in these cases:

	    - before we attempt to assign resources automatically,
	    - if we fail to assign resources automatically,
	    - after disabling a device

    IORESOURCE_DISABLED
	Set by pnp_assign_{io,mem,etc}() when automatic assignment fails.
	Also set by PNPBIOS and PNPACPI for:

	    - invalid IRQs or GSI registration failures
	    - invalid DMA channels
	    - I/O ports above 0x10000
	    - mem ranges with negative length

After this patch, there is no pnp_resource_table, and the resource list
entries use the flags like this:

    IORESOURCE_UNSET
	This flag is no longer used in PNP.  Instead of keeping
	IORESOURCE_UNSET entries in the resource list, we remove
	entries from the list and free them.

    IORESOURCE_AUTO
	No change in meaning: it still means the resource was assigned
	automatically by pnp_assign_{port,mem,etc}(), but these functions
	now set the bit explicitly.

	We still "clean" a device's resource list in the same places,
	but rather than reinitializing IORESOURCE_AUTO entries, we
	just remove them from the list.

	Note that IORESOURCE_AUTO entries are always at the end of the
	list, so removing them doesn't reorder other list entries.
	This is because non-IORESOURCE_AUTO entries are added by the
	ISAPNP, PNPBIOS, or PNPACPI "get resources" methods and by the
	sysfs "set" command.  In each of these cases, we completely free
	the resource list first.

    IORESOURCE_DISABLED
	In addition to the cases where we used to set this flag, ISAPNP now
	adds an IORESOURCE_DISABLED resource when it reads a configuration
	register with a "disabled" value.

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Len Brown <len.brown@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>

1 files changed, 17 insertions, 8 deletions

diff --git a/drivers/pnp/core.c b/drivers/pnp/core.c
index 20771b7..7182da9 100644
--- a/drivers/pnp/core.c
+++ b/drivers/pnp/core.c
@@ -99,6 +99,21 @@ static void pnp_free_ids(struct pnp_dev *dev)
 	}
 }
 
+void pnp_free_resource(struct pnp_resource *pnp_res)
+{
+	list_del(&pnp_res->list);
+	kfree(pnp_res);
+}
+
+void pnp_free_resources(struct pnp_dev *dev)
+{
+	struct pnp_resource *pnp_res, *tmp;
+
+	list_for_each_entry_safe(pnp_res, tmp, &dev->resources, list) {
+		pnp_free_resource(pnp_res);
+	}
+}
+
 static void pnp_release_device(struct device *dmdev)
 {
 	struct pnp_dev *dev = to_pnp_dev(dmdev);
@@ -106,7 +121,7 @@ static void pnp_release_device(struct device *dmdev)
 	pnp_free_option(dev->independent);
 	pnp_free_option(dev->dependent);
 	pnp_free_ids(dev);
-	kfree(dev->res);
+	pnp_free_resources(dev);
 	kfree(dev);
 }
 
@@ -119,12 +134,7 @@ struct pnp_dev *pnp_alloc_dev(struct pnp_protocol *protocol, int id, char *pnpid
 	if (!dev)
 		return NULL;
 
-	dev->res = kzalloc(sizeof(struct pnp_resource_table), GFP_KERNEL);
-	if (!dev->res) {
-		kfree(dev);
-		return NULL;
-	}
-
+	INIT_LIST_HEAD(&dev->resources);
 	dev->protocol = protocol;
 	dev->number = id;
 	dev->dma_mask = DMA_24BIT_MASK;
@@ -140,7 +150,6 @@ struct pnp_dev *pnp_alloc_dev(struct pnp_protocol *protocol, int id, char *pnpid
 
 	dev_id = pnp_add_id(dev, pnpid);
 	if (!dev_id) {
-		kfree(dev->res);
 		kfree(dev);
 		return NULL;
 	}