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Subject[PATCH] PnPBIOS patch #10
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Date
Here's the remainder of the changes I made to the PnPBIOS driver.

- Minor formatting changes
- Use spin_lock_init() instead of "= SPIN_LOCK_UNLOCKED"
- Add some comments
- Don't export pnpbios_announce_device, which isn't
used by anyone else
- Don't lock when accessing info that doesn't change
- Update Christian Schmidt's e-mail address
- Add pnpbios_get_device() The idea here is to provide a
replacement for pnpbios_find_device(), which returns
a pointer into the driver's device list, which must
be locked since it can be updated. The _get_ function
copies the node into a struct pci_dev provided by the
caller, instead of returning a pointer, so the caller
needn't lock to read the info. Instead of a pointer
to a previous node, the caller provides the previous
node number.

Tested by me. Should be quite safe to apply.

Alan: Please let me know if you have criticisms of the patch.

--
Thomas Hood

The Patch:
--- linux-2.4.13-ac7/drivers/pnp/pnp_bios.c Sat Nov 3 18:15:27 2001
+++ linux-2.4.13-ac7-fix/drivers/pnp/pnp_bios.c Sat Nov 3 20:09:10 2001
@@ -1,7 +1,7 @@
/*
* PnP BIOS services
*
- * Originally (C) 1998 Christian Schmidt (chr.schmidt@tu-bs.de)
+ * Originally (C) 1998 Christian Schmidt <schmidt@digadd.de>
* Modifications (c) 1998 Tom Lees <tom@lpsg.demon.co.uk>
* Minor reorganizations by David Hinds <dahinds@users.sourceforge.net>
* Modifications (c) 2001 by Thomas Hood <jdthood@mail.com>
@@ -86,12 +86,12 @@
static union pnp_bios_expansion_header * pnp_bios_hdr = NULL;

/* The PnP BIOS entries in the GDT */
-#define PNP_GDT 0x0060
-#define PNP_CS32 (PNP_GDT+0x00) /* segment for calling fn */
-#define PNP_CS16 (PNP_GDT+0x08) /* code segment for BIOS */
-#define PNP_DS (PNP_GDT+0x10) /* data segment for BIOS */
-#define PNP_TS1 (PNP_GDT+0x18) /* transfer data segment */
-#define PNP_TS2 (PNP_GDT+0x20) /* another data segment */
+#define PNP_GDT (0x0060)
+#define PNP_CS32 (PNP_GDT+0x00) /* segment for calling fn */
+#define PNP_CS16 (PNP_GDT+0x08) /* code segment for BIOS */
+#define PNP_DS (PNP_GDT+0x10) /* data segment for BIOS */
+#define PNP_TS1 (PNP_GDT+0x18) /* transfer data segment */
+#define PNP_TS2 (PNP_GDT+0x20) /* another data segment */

/*
* These are some opcodes for a "static asmlinkage"
@@ -137,7 +137,7 @@
u32 pnp_bios_fault_eip;
u32 pnp_bios_is_utter_crap = 0;

-static spinlock_t pnp_bios_lock = SPIN_LOCK_UNLOCKED;
+static spinlock_t pnp_bios_lock;

static inline u16 call_pnp_bios(u16 func, u16 arg1, u16 arg2, u16 arg3,
u16 arg4, u16 arg5, u16 arg6, u16 arg7)
@@ -793,26 +793,26 @@
* presumably it continues to describe the current config.
* For those BIOSes that can change the current config, we
* keep the information in the devlist up to date.
+ *
+ * Note that it is currently assumed that the list does not
+ * grow or shrink in size after init time, and slot_name
+ * never changes.
*/

static LIST_HEAD(pnpbios_devices);

-spinlock_t pnpbios_devices_lock = SPIN_LOCK_UNLOCKED;
-EXPORT_SYMBOL(pnpbios_devices_lock);
+static spinlock_t pnpbios_devices_lock;

static int inline pnpbios_insert_device(struct pci_dev *dev)
{
- unsigned long flags;
-
- spin_lock_irqsave(&pnpbios_devices_lock, flags);

/*
* FIXME: Check for re-add of existing node;
* return -1 if node already present
*/
- list_add_tail(&dev->global_list, &pnpbios_devices);

- spin_unlock_irqrestore(&pnpbios_devices_lock, flags);
+ /* We don't lock because we only do this at init time */
+ list_add_tail(&dev->global_list, &pnpbios_devices);

return 0;
}
@@ -898,62 +898,93 @@
nodes_got, nodes_got != 1 ? "s" : "", devs);
}

+/*
+ * Return pointer to device node after *prev with name pnpid[]
+ *
+ * Deprecated, since the information in the node may be
+ * updated while it's being read.
+ * Use pnpbios_get_device instead.
+ */
struct pci_dev *pnpbios_find_device(char *pnpid, struct pci_dev *prev)
{
struct pci_dev *dev;
- int nodenum;
- unsigned long flags;
+ int minnodenum;

- nodenum = 0;
+ minnodenum = 0;
if(prev)
- nodenum=prev->devfn + 1;
-
- spin_lock_irqsave(&pnpbios_devices_lock, flags);
+ minnodenum=prev->devfn + 1;

+ /*
+ * We don't lock. We assume that the list can be
+ * traversed and slot_name searched at any time,
+ * since this is static information.
+ */
pnpbios_for_each_dev(dev) {
- if(dev->devfn >= nodenum) {
+ if(dev->devfn >= minnodenum) {
if(memcmp(dev->slot_name, pnpid, 7)==0)
- goto out;
+ return dev;
}
}
- dev = (struct pci_dev *)NULL;

-out:
- spin_unlock_irqrestore(&pnpbios_devices_lock, flags);
-
- return dev;
+ return (struct pci_dev *)NULL;
}

EXPORT_SYMBOL(pnpbios_find_device);

-static struct pci_dev *__pnpbios_find_device_by_nodenum( u8 nodenum )
+/*
+ * Copy device node with node number greater than prevnodenum
+ * and with name pnpid[] to *dev.
+ * Return node number on success, -1 on failure.
+ *
+ * Note: Call with prevnodenum = -1 the first time.
+ */
+int pnpbios_get_device(char *pnpid, int prevnodenum, struct pci_dev *usrdev)
+{
+ struct pci_dev *dev;
+
+ pnpbios_for_each_dev(dev) {
+ if((int)dev->devfn > prevnodenum && memcmp(dev->slot_name,pnpid,7)==0) {
+ unsigned long flags;
+ /* We lock to prevent updates while we are making a copy */
+ spin_lock_irqsave(&pnpbios_devices_lock, flags);
+ memcpy(usrdev,dev,sizeof(struct pci_dev));
+ spin_unlock_irqrestore(&pnpbios_devices_lock, flags);
+ usrdev->global_list.prev = NULL;
+ usrdev->global_list.next = NULL;
+ return (int)dev->devfn;
+ }
+ }
+
+ /* Didn't got it */
+ return -1;
+}
+
+EXPORT_SYMBOL(pnpbios_get_device);
+
+static struct pci_dev *pnpbios_find_device_by_nodenum( u8 nodenum )
{
struct pci_dev *dev;

pnpbios_for_each_dev(dev) {
if(dev->devfn == nodenum)
- goto out;
+ return dev;
}
- dev = (struct pci_dev *)NULL;

-out:
- return dev;
+ return NULL;
}

static void pnpbios_update_devlist( u8 nodenum, struct pnp_bios_node *data )
{
struct pci_dev *dev;
- unsigned long flags;
-
- spin_lock_irqsave(&pnpbios_devices_lock, flags);

- dev = __pnpbios_find_device_by_nodenum( nodenum );
+ dev = pnpbios_find_device_by_nodenum( nodenum );
if ( dev ) {
+ unsigned long flags;
+ spin_lock_irqsave(&pnpbios_devices_lock, flags);
pnpbios_node_resource_data_to_dev(data,dev);
+ spin_unlock_irqrestore(&pnpbios_devices_lock, flags);
}

- spin_unlock_irqrestore(&pnpbios_devices_lock, flags);
-
return;
}

@@ -980,7 +1011,7 @@
* pnpbios_device_id structure or %NULL if there is no match.
*/

-const struct pnpbios_device_id *
+static const struct pnpbios_device_id *
pnpbios_match_device(const struct pnpbios_device_id *ids, const struct pci_dev *dev)
{
while (*ids->id)
@@ -992,7 +1023,7 @@
return NULL;
}

-int pnpbios_announce_device(struct pnpbios_driver *drv, struct pci_dev *dev)
+static int pnpbios_announce_device(struct pnpbios_driver *drv, struct pci_dev *dev)
{
const struct pnpbios_device_id *id;
int ret = 0;
@@ -1017,8 +1048,6 @@
return ret;
}

-EXPORT_SYMBOL(pnpbios_announce_device);
-
/**
* pnpbios_register_driver - register a new pci driver
* @drv: the driver structure to register
@@ -1206,6 +1235,7 @@
int i, length;

spin_lock_init(&pnp_bios_lock);
+ spin_lock_init(&pnpbios_devices_lock);

if(pnpbios_disabled) {
printk(KERN_INFO "PnPBIOS: Disabled.\n");
--- linux-2.4.13-ac7/include/linux/pnp_bios.h Sat Nov 3 18:29:25 2001
+++ linux-2.4.13-ac7-fix/include/linux/pnp_bios.h Sat Nov 3 19:15:11 2001
@@ -137,8 +137,8 @@
for(dev = pnpbios_dev_g(pnpbios_devices.next); dev != pnpbios_dev_g(&pnpbios_devices); dev = pnpbios_dev_g(dev->global_list.next))

/* exported functions */
-extern struct pci_dev *pnpbios_find_device(char *pnpid, struct pci_dev *dev);
-extern int pnpbios_announce_device(struct pnpbios_driver *drv, struct pci_dev *dev);
+extern struct pci_dev *pnpbios_find_device(char *pnpid, struct pci_dev *prevdev);
+extern int pnpbios_get_device(char *pnpid, int prevnodenum, struct pci_dev *dev);
extern int pnpbios_register_driver(struct pnpbios_driver *drv);
extern void pnpbios_unregister_driver(struct pnpbios_driver *drv);

@@ -202,11 +202,6 @@
static __inline__ struct pci_dev *pnpbios_find_device(char *pnpid, struct pci_dev *dev)
{
return NULL;
-}
-
-static __inline__ int pnpbios_announce_device(struct pnpbios_driver *drv, struct pci_dev *dev)
-{
- return 0;
}

static __inline__ int pnpbios_register_driver(struct pnpbios_driver *drv)
-
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