Fix USDPAA dma_mem allocator when blocks needed to be split

Also rework the fragment management to eliminate fragmentation

Signed-off-by: Roy Pledge <Roy.Pledge@freescale.com>
Change-Id: Ieb1aaf3b7d7e3d42b78efe2411952f10bbd2803d
Reviewed-on: http://git.am.freescale.net:8181/4774
Tested-by: Review Code-CDREVIEW <CDREVIEW@freescale.com>
Reviewed-by: Wang Haiying-R54964 <Haiying.Wang@freescale.com>
Reviewed-by: Thorpe Geoff-R01361 <Geoff.Thorpe@freescale.com>
Reviewed-by: Rivera Jose-B46482 <German.Rivera@freescale.com>

1 files changed, 51 insertions, 90 deletions

diff --git a/drivers/staging/fsl_qbman/fsl_usdpaa.c b/drivers/staging/fsl_qbman/fsl_usdpaa.c
index 033cfbb..b6f0ef2 100644
--- a/drivers/staging/fsl_qbman/fsl_usdpaa.c
+++ b/drivers/staging/fsl_qbman/fsl_usdpaa.c
@@ -220,57 +220,24 @@ static struct mem_fragment *split_frag(struct mem_fragment *frag)
 	return x[2];
 }
 
-/* Conversely, when a fragment is released we look to see whether its
- * similarly-split siblings are free to be reassembled. */
-static struct mem_fragment *merge_frag(struct mem_fragment *frag)
+/* Walk the list of fragments and adjoin neighbouring segments if possible */
+static void compress_frags(void)
 {
-	/* If this fragment can be merged with its siblings, it will have
-	 * newbase and newlen as its geometry. */
-	uint64_t newlen = frag->len << 2;
-	uint64_t newbase = frag->base & ~(newlen - 1);
-	struct mem_fragment *tmp, *leftmost = frag, *rightmost = frag;
-
-	/* If this fragment is already at root size don't allow merge */
-	if (frag->len == frag->root_len)
-		return NULL;
-	/* Scan left until we find the start */
-	tmp = list_entry(frag->list.prev, struct mem_fragment, list);
-	while ((&tmp->list != &mem_list) && (tmp->base >= newbase)) {
-		if (tmp->refs)
-			return NULL;
-		if (tmp->len != frag->len)
-			return NULL;
-		leftmost = tmp;
-		tmp = list_entry(tmp->list.prev, struct mem_fragment, list);
-	}
-	/* Scan right until we find the end */
-	tmp = list_entry(frag->list.next, struct mem_fragment, list);
-	while ((&tmp->list != &mem_list) && (tmp->base < (newbase + newlen))) {
-		if (tmp->refs)
-			return NULL;
-		if (tmp->len != frag->len)
-			return NULL;
-		rightmost = tmp;
-		tmp = list_entry(tmp->list.next, struct mem_fragment, list);
-	}
-	if (leftmost == rightmost)
-		return NULL;
-	/* OK, we can merge */
-	frag = leftmost;
-	frag->len = newlen;
-	frag->pfn_len = newlen >> PAGE_SHIFT;
-	while (1) {
-		int lastone;
-		tmp = list_entry(frag->list.next, struct mem_fragment, list);
-		lastone = (tmp == rightmost);
-		if (&tmp->list == &mem_list)
-			break;
-		list_del(&tmp->list);
-		kfree(tmp);
-		if (lastone)
-			break;
+	/* Walk the fragment list and combine fragments */
+	struct mem_fragment *frag, *tmpfrag;
+	list_for_each_entry_safe(frag, tmpfrag, &mem_list, list) {
+		struct mem_fragment *next_frag =
+			list_entry(frag->list.next, struct mem_fragment, list);
+		if (frag->refs == 0 &&
+		    frag->len < frag->root_len &&
+		    &next_frag->list != &mem_list) {
+			if (next_frag->refs == 0) {
+				/* Merge with next */
+				next_frag->len += frag->len;
+				list_del(&frag->list);
+			}
+		}
 	}
-	return frag;
 }
 
 /* Hook from arch/powerpc/mm/mem.c */
@@ -464,8 +431,8 @@ __maybe_unused static void dump_frags(void)
 	struct mem_fragment *frag;
 	int i = 0;
 	list_for_each_entry(frag, &mem_list, list) {
-		pr_info("FRAG %d: base 0x%llx len 0x%llx root_len 0x%llx\n",
-			i, frag->base, frag->len, frag->root_len);
+		pr_info("FRAG %d: base 0x%llx len 0x%llx root_len 0x%llx refs %d\n",
+			i, frag->base, frag->len, frag->root_len, frag->refs);
 		++i;
 	}
 }
@@ -558,15 +525,12 @@ static int usdpaa_release(struct inode *inode, struct file *filp)
 		}
 		/* Check each fragment and merge if the ref count is 0 */
 		for (i = 0; i < map->frag_count; i++) {
-			if (!--current_frag->refs) {
-				struct mem_fragment *frag = current_frag;
-				do {
-					frag = merge_frag(frag);
-				} while (frag);
-			}
+			--current_frag->refs;
 			current_frag = list_entry(current_frag->list.next,
 						  struct mem_fragment, list);
 		}
+
+		compress_frags();
 		list_del(&map->list);
 		kfree(map);
 	}
@@ -608,8 +572,6 @@ static int check_mmap_dma(struct ctx *ctx, struct vm_area_struct *vma,
 		for (i = 0; i < map->frag_count; i++) {
 			if (frag->pfn_base == vma->vm_pgoff) {
 				*match = 1;
-				if (frag->len != (vma->vm_end - vma->vm_start))
-					return -EINVAL;
 				*pfn = frag->pfn_base;
 				return 0;
 			}
@@ -705,6 +667,7 @@ static unsigned long usdpaa_get_unmapped_area(struct file *file,
 	while (vma) {
 		if ((addr + len) < vma->vm_start)
 			return addr;
+
 		addr = USDPAA_MEM_ROUNDUP(vma->vm_end, len);
 		vma = vma->vm_next;
 	}
@@ -914,7 +877,7 @@ static long ioctl_dma_map(struct file *fp, struct ctx *ctx,
 				/* See if the next x fragments are free
 				   and can accomidate the size */
 				u32 found_size = largest_page;
-				next_frag = list_entry(frag->list.next,
+				next_frag = list_entry(frag->list.prev,
 						       struct mem_fragment,
 						       list);
 				/* If the fragement is too small check
@@ -926,6 +889,10 @@ static long ioctl_dma_map(struct file *fp, struct ctx *ctx,
 					    next_frag->len == 0)
 						break; /* not enough space */
 					found_size += next_frag->len;
+					next_frag = list_entry(
+						next_frag->list.prev,
+						struct mem_fragment,
+						list);
 				}
 				if (found_size >= i->len) {
 					/* Success! there is enough contigous
@@ -952,20 +919,23 @@ do_map:
 		BUG_ON(next_frag->len == 0);
 		while ((next_frag->len + so_far) > i->len) {
 			/* Split frag until they match */
-			split_frag(next_frag);
+			if (next_frag == start_frag)
+				start_frag = next_frag = split_frag(next_frag);
+			else
+				next_frag = split_frag(next_frag);
 		}
 		so_far += next_frag->len;
 		++frag_count;
-		next_frag = list_entry(next_frag->list.next,
+		next_frag = list_entry(next_frag->list.prev,
 				       struct mem_fragment, list);
 	}
 
 	/* we need to reserve start count fragments starting at start frag */
-	next_frag = start_frag;
 	for (k = 0; k < frag_count; k++) {
-		next_frag->refs++;
-		next_frag = list_entry(next_frag->list.next,
-				       struct mem_fragment, list);
+		start_frag->refs++;
+		if (k+1 != frag_count)
+			start_frag = list_entry(start_frag->list.prev,
+					       struct mem_fragment, list);
 	}
 
 	start_frag->flags = i->flags;
@@ -982,32 +952,23 @@ do_map:
 	i->phys_addr = start_frag->base;
 out:
 	spin_unlock(&mem_lock);
+
 	if (!ret) {
 		unsigned long longret;
-		unsigned long next_addr = PAGE_SIZE;
-		next_frag = start_frag;
-		for (k = 0; k < frag_count; k++) {
-			down_write(&current->mm->mmap_sem);
-			longret = do_mmap_pgoff(fp, next_addr, next_frag->len,
-						PROT_READ |
-						(i->flags &
-						 USDPAA_DMA_FLAG_RDONLY ? 0
-						 : PROT_WRITE),
-						MAP_SHARED,
-						next_frag->pfn_base);
-			up_write(&current->mm->mmap_sem);
-			if (longret & ~PAGE_MASK)
-				ret = (int)longret;
-			else {
-				if (k == 0)
-					i->ptr = (void *)longret;
-				else
-					BUG_ON(next_addr != longret);
-				next_addr = longret + next_frag->len;
-			}
-			next_frag = list_entry(next_frag->list.next,
-					       struct mem_fragment, list);
-		}
+		down_write(&current->mm->mmap_sem);
+		longret = do_mmap_pgoff(fp, PAGE_SIZE, map->total_size,
+					PROT_READ |
+					(i->flags &
+					 USDPAA_DMA_FLAG_RDONLY ? 0
+					 : PROT_WRITE),
+					MAP_SHARED,
+					start_frag->pfn_base);
+		up_write(&current->mm->mmap_sem);
+		if (longret & ~PAGE_MASK)
+			ret = (int)longret;
+		else
+			i->ptr = (void *)longret;
+
 	} else
 		kfree(map);
 	return ret;