• Bjorn Helgaas's avatar
    PNP: replace pnp_resource_table with dynamically allocated resources · aee3ad81
    Bjorn Helgaas authored
    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: default avatarBjorn Helgaas <bjorn.helgaas@hp.com>
    Signed-off-by: default avatarLen Brown <len.brown@intel.com>
    Signed-off-by: default avatarAndi Kleen <ak@linux.intel.com>
    aee3ad81
core.c 4.66 KB