[PATCH] PATCH -- pci_pool and CONFIG_DEBUG_SLAB

I got burnt one too many time by mismatches between
the pci_pool and "real" slabs... something changed in
mm/slab.c and broke a driver, so I'm going for the real
fix this time.  Having poisoning that _works_ is a huge
help in the innards of the USB host controller drivers.

This patch gets rid of some #ifdefs and makes the pci_pool
code poison memory if CONFIG_DEBUG_SLAB is set.
The functionality has always been there, but this makes
it simpler to get at.

drivers/pci/pci.c

@@ -1710,7 +1710,6 @@ struct pci_pool {	/* the pool */
 	spinlock_t		lock;
 	size_t			blocks_per_page;
 	size_t			size;
-	int			flags;
 	struct pci_dev		*dev;
 	size_t			allocation;
 	char			name [32];
@@ -1727,8 +1726,6 @@ struct pci_page {	/* cacheable header for 'allocation' bytes */
 #define	POOL_TIMEOUT_JIFFIES	((100 /* msec */ * HZ) / 1000)
 #define	POOL_POISON_BYTE	0xa7
 
-// #define CONFIG_PCIPOOL_DEBUG
-
 
 /**
  * pci_pool_create - Creates a pool of pci consistent memory blocks, for dma.
@@ -1737,7 +1734,7 @@ struct pci_page {	/* cacheable header for 'allocation' bytes */
  * @size: size of the blocks in this pool.
  * @align: alignment requirement for blocks; must be a power of two
  * @allocation: returned blocks won't cross this boundary (or zero)
- * @flags: SLAB_* flags (not all are supported).
+ * @mem_flags: SLAB_* flags.
  *
  * Returns a pci allocation pool with the requested characteristics, or
  * null if one can't be created.  Given one of these pools, pci_pool_alloc()
@@ -1753,7 +1750,7 @@ struct pci_page {	/* cacheable header for 'allocation' bytes */
  */
 struct pci_pool *
 pci_pool_create (const char *name, struct pci_dev *pdev,
-	size_t size, size_t align, size_t allocation, int flags)
+	size_t size, size_t align, size_t allocation, int mem_flags)
 {
 	struct pci_pool		*retval;
 
@@ -1777,13 +1774,9 @@ pci_pool_create (const char *name, struct pci_dev *pdev,
 	} else if (allocation < size)
 		return 0;
 
-	if (!(retval = kmalloc (sizeof *retval, flags)))
+	if (!(retval = kmalloc (sizeof *retval, mem_flags)))
 		return retval;
 
-#ifdef	CONFIG_PCIPOOL_DEBUG
-	flags |= SLAB_POISON;
-#endif
-
 	strncpy (retval->name, name, sizeof retval->name);
 	retval->name [sizeof retval->name - 1] = 0;
 
@@ -1791,17 +1784,10 @@ pci_pool_create (const char *name, struct pci_dev *pdev,
 	INIT_LIST_HEAD (&retval->page_list);
 	spin_lock_init (&retval->lock);
 	retval->size = size;
-	retval->flags = flags;
 	retval->allocation = allocation;
 	retval->blocks_per_page = allocation / size;
 	init_waitqueue_head (&retval->waitq);
 
-#ifdef CONFIG_PCIPOOL_DEBUG
-	printk (KERN_DEBUG "pcipool create %s/%s size %d, %d/page (%d alloc)\n",
-		pdev ? pdev->slot_name : NULL, retval->name, size,
-		retval->blocks_per_page, allocation);
-#endif
-
 	return retval;
 }
 
@@ -1824,8 +1810,9 @@ pool_alloc_page (struct pci_pool *pool, int mem_flags)
 					    &page->dma);
 	if (page->vaddr) {
 		memset (page->bitmap, 0xff, mapsize);	// bit set == free
-		if (pool->flags & SLAB_POISON)
+#ifdef	CONFIG_DEBUG_SLAB
 		memset (page->vaddr, POOL_POISON_BYTE, pool->allocation);
+#endif
 		list_add (&page->page_list, &pool->page_list);
 	} else {
 		kfree (page);
@@ -1851,8 +1838,9 @@ pool_free_page (struct pci_pool *pool, struct pci_page *page)
 {
 	dma_addr_t	dma = page->dma;
 
-	if (pool->flags & SLAB_POISON)
+#ifdef	CONFIG_DEBUG_SLAB
 	memset (page->vaddr, POOL_POISON_BYTE, pool->allocation);
+#endif
 	pci_free_consistent (pool->dev, pool->allocation, page->vaddr, dma);
 	list_del (&page->page_list);
 	kfree (page);
@@ -1871,12 +1859,6 @@ pci_pool_destroy (struct pci_pool *pool)
 {
 	unsigned long		flags;
 
-#ifdef CONFIG_PCIPOOL_DEBUG
-	printk (KERN_DEBUG "pcipool destroy %s/%s\n",
-		pool->dev ? pool->dev->slot_name : NULL,
-		pool->name);
-#endif
-
 	spin_lock_irqsave (&pool->lock, flags);
 	while (!list_empty (&pool->page_list)) {
 		struct pci_page		*page;
@@ -2010,30 +1992,27 @@ pci_pool_free (struct pci_pool *pool, void *vaddr, dma_addr_t dma)
 			pool->name, vaddr, (unsigned long) dma);
 		return;
 	}
-#ifdef	CONFIG_PCIPOOL_DEBUG
-	if (((dma - page->dma) + (void *)page->vaddr) != vaddr) {
-		printk (KERN_ERR "pci_pool_free %s/%s, %p (bad vaddr)/%lx\n",
-			pool->dev ? pool->dev->slot_name : NULL,
-			pool->name, vaddr, (unsigned long) dma);
-		return;
-	}
-#endif
 
 	block = dma - page->dma;
 	block /= pool->size;
 	map = block / BITS_PER_LONG;
 	block %= BITS_PER_LONG;
 
-#ifdef	CONFIG_PCIPOOL_DEBUG
+#ifdef	CONFIG_DEBUG_SLAB
+	if (((dma - page->dma) + (void *)page->vaddr) != vaddr) {
+		printk (KERN_ERR "pci_pool_free %s/%s, %p (bad vaddr)/%lx\n",
+			pool->dev ? pool->dev->slot_name : NULL,
+			pool->name, vaddr, (unsigned long) dma);
+		return;
+	}
 	if (page->bitmap [map] & (1UL << block)) {
 		printk (KERN_ERR "pci_pool_free %s/%s, dma %x already free\n",
 			pool->dev ? pool->dev->slot_name : NULL,
 			pool->name, dma);
 		return;
 	}
-#endif
-	if (pool->flags & SLAB_POISON)
 	memset (vaddr, POOL_POISON_BYTE, pool->size);
+#endif
 
 	spin_lock_irqsave (&pool->lock, flags);
 	set_bit (block, &page->bitmap [map]);