[PATCH v2 07/16] vfio/ccw: remove unnecessary malloc alignment

[Eric Farman <farman@xxxxxxxxxxxxx>]

Everything about this allocation is harder than necessary,
since the memory allocation is already aligned to our needs.
Break them apart for readability, instead of doing the
funky artithmetic.

Of the structures that are involved, only ch_ccw needs the
GFP_DMA flag, so the others can be allocated without it.

Signed-off-by: Eric Farman <farman@xxxxxxxxxxxxx>
---
 drivers/s390/cio/vfio_ccw_cp.c | 43 ++++++++++++++++++----------------
 1 file changed, 23 insertions(+), 20 deletions(-)

diff --git a/drivers/s390/cio/vfio_ccw_cp.c b/drivers/s390/cio/vfio_ccw_cp.c
index d41d94cecdf8..99332c6f6010 100644
--- a/drivers/s390/cio/vfio_ccw_cp.c
+++ b/drivers/s390/cio/vfio_ccw_cp.c
@@ -311,40 +311,41 @@ static inline int is_tic_within_range(struct ccw1 *ccw, u32 head, int len)
 static struct ccwchain *ccwchain_alloc(struct channel_program *cp, int len)
 {
 	struct ccwchain *chain;
-	void *data;
-	size_t size;
-
-	/* Make ccw address aligned to 8. */
-	size = ((sizeof(*chain) + 7L) & -8L) +
-		sizeof(*chain->ch_ccw) * len +
-		sizeof(*chain->ch_pa) * len;
-	chain = kzalloc(size, GFP_DMA | GFP_KERNEL);
+
+	chain = kzalloc(sizeof(*chain), GFP_KERNEL);
 	if (!chain)
 		return NULL;
 
-	data = (u8 *)chain + ((sizeof(*chain) + 7L) & -8L);
-	chain->ch_ccw = (struct ccw1 *)data;
-
-	data = (u8 *)(chain->ch_ccw) + sizeof(*chain->ch_ccw) * len;
-	chain->ch_pa = (struct page_array *)data;
+	chain->ch_ccw = kcalloc(len, sizeof(*chain->ch_ccw), GFP_DMA | GFP_KERNEL);
+	if (!chain->ch_ccw)
+		goto out_err;
 
-	chain->ch_len = len;
+	chain->ch_pa = kcalloc(len, sizeof(*chain->ch_pa), GFP_KERNEL);
+	if (!chain->ch_pa)
+		goto out_err;
 
 	list_add_tail(&chain->next, &cp->ccwchain_list);
 
 	return chain;
+
+out_err:
+	kfree(chain->ch_ccw);
+	kfree(chain);
+	return NULL;
 }
 
 static void ccwchain_free(struct ccwchain *chain)
 {
 	list_del(&chain->next);
+	kfree(chain->ch_pa);
+	kfree(chain->ch_ccw);
 	kfree(chain);
 }
 
 /* Free resource for a ccw that allocated memory for its cda. */
 static void ccwchain_cda_free(struct ccwchain *chain, int idx)
 {
-	struct ccw1 *ccw = chain->ch_ccw + idx;
+	struct ccw1 *ccw = &chain->ch_ccw[idx];
 
 	if (ccw_is_tic(ccw))
 		return;
@@ -443,6 +444,8 @@ static int ccwchain_handle_ccw(u32 cda, struct channel_program *cp)
 	chain = ccwchain_alloc(cp, len);
 	if (!chain)
 		return -ENOMEM;
+
+	chain->ch_len = len;
 	chain->ch_iova = cda;
 
 	/* Copy the actual CCWs into the new chain */
@@ -464,7 +467,7 @@ static int ccwchain_loop_tic(struct ccwchain *chain, struct channel_program *cp)
 	int i, ret;
 
 	for (i = 0; i < chain->ch_len; i++) {
-		tic = chain->ch_ccw + i;
+		tic = &chain->ch_ccw[i];
 
 		if (!ccw_is_tic(tic))
 			continue;
@@ -681,7 +684,7 @@ void cp_free(struct channel_program *cp)
 	cp->initialized = false;
 	list_for_each_entry_safe(chain, temp, &cp->ccwchain_list, next) {
 		for (i = 0; i < chain->ch_len; i++) {
-			page_array_unpin_free(chain->ch_pa + i, vdev);
+			page_array_unpin_free(&chain->ch_pa[i], vdev);
 			ccwchain_cda_free(chain, i);
 		}
 		ccwchain_free(chain);
@@ -739,8 +742,8 @@ int cp_prefetch(struct channel_program *cp)
 	list_for_each_entry(chain, &cp->ccwchain_list, next) {
 		len = chain->ch_len;
 		for (idx = 0; idx < len; idx++) {
-			ccw = chain->ch_ccw + idx;
-			pa = chain->ch_pa + idx;
+			ccw = &chain->ch_ccw[idx];
+			pa = &chain->ch_pa[idx];
 
 			ret = ccwchain_fetch_one(ccw, pa, cp);
 			if (ret)
@@ -866,7 +869,7 @@ bool cp_iova_pinned(struct channel_program *cp, u64 iova, u64 length)
 
 	list_for_each_entry(chain, &cp->ccwchain_list, next) {
 		for (i = 0; i < chain->ch_len; i++)
-			if (page_array_iova_pinned(chain->ch_pa + i, iova, length))
+			if (page_array_iova_pinned(&chain->ch_pa[i], iova, length))
 				return true;
 	}
 
-- 
2.34.1