[RFC PATCH] RDMA/siw: use kzalloc_flex

[bernard.metzler@linux.dev]

From: Bernard Metzler <bernard.metzler@linux.dev>

Simplify umem allocation by using flexible array member.
Add __counted_by to get extra runtime analysis.

Suggested-by: Rosen Penev <rosenp@gmail.com>
Signed-off-by: Bernard Metzler <bernard.metzler@linux.dev>
---
 drivers/infiniband/sw/siw/siw.h     |  4 ++--
 drivers/infiniband/sw/siw/siw_mem.c | 19 ++++++-------------
 drivers/infiniband/sw/siw/siw_mem.h |  2 +-
 3 files changed, 9 insertions(+), 16 deletions(-)

diff --git a/drivers/infiniband/sw/siw/siw.h b/drivers/infiniband/sw/siw/siw.h
index f5fd71717b80..a4088caec2ae 100644
--- a/drivers/infiniband/sw/siw/siw.h
+++ b/drivers/infiniband/sw/siw/siw.h
@@ -119,9 +119,9 @@ struct siw_page_chunk {
 
 struct siw_umem {
 	struct ib_umem *base_mem;
-	struct siw_page_chunk *page_chunk;
-	int num_pages;
+	int num_chunks;
 	u64 fp_addr; /* First page base address */
+	struct siw_page_chunk page_chunk[] __counted_by(num_chunks);
 };
 
 struct siw_pble {
diff --git a/drivers/infiniband/sw/siw/siw_mem.c b/drivers/infiniband/sw/siw/siw_mem.c
index 98c802b3ed72..56d24db729d0 100644
--- a/drivers/infiniband/sw/siw/siw_mem.c
+++ b/drivers/infiniband/sw/siw/siw_mem.c
@@ -41,16 +41,14 @@ struct siw_mem *siw_mem_id2obj(struct siw_device *sdev, int stag_index)
 
 void siw_umem_release(struct siw_umem *umem)
 {
-	int i, num_pages = umem->num_pages;
+	int i, num_chunks = umem->num_chunks;
 
 	if (umem->base_mem)
 		ib_umem_release(umem->base_mem);
 
-	for (i = 0; num_pages > 0; i++) {
+	for (i = 0; i < num_chunks; i++)
 		kfree(umem->page_chunk[i].plist);
-		num_pages -= PAGES_PER_CHUNK;
-	}
-	kfree(umem->page_chunk);
+
 	kfree(umem);
 }
 
@@ -347,16 +345,12 @@ struct siw_umem *siw_umem_get(struct ib_device *base_dev, u64 start,
 	num_pages = PAGE_ALIGN(start + len - first_page_va) >> PAGE_SHIFT;
 	num_chunks = (num_pages >> CHUNK_SHIFT) + 1;
 
-	umem = kzalloc_obj(*umem);
+	umem = kzalloc_flex(*umem, page_chunk, num_chunks);
 	if (!umem)
 		return ERR_PTR(-ENOMEM);
 
-	umem->page_chunk =
-		kzalloc_objs(struct siw_page_chunk, num_chunks);
-	if (!umem->page_chunk) {
-		rv = -ENOMEM;
-		goto err_out;
-	}
+	umem->num_chunks = num_chunks;
+
 	base_mem = ib_umem_get(base_dev, start, len, rights);
 	if (IS_ERR(base_mem)) {
 		rv = PTR_ERR(base_mem);
@@ -385,7 +379,6 @@ struct siw_umem *siw_umem_get(struct ib_device *base_dev, u64 start,
 		umem->page_chunk[i].plist = plist;
 		while (nents--) {
 			*plist = sg_page_iter_page(&sg_iter);
-			umem->num_pages++;
 			num_pages--;
 			plist++;
 			if (!__sg_page_iter_next(&sg_iter))
diff --git a/drivers/infiniband/sw/siw/siw_mem.h b/drivers/infiniband/sw/siw/siw_mem.h
index 8e769d30e2ac..86af61d422d5 100644
--- a/drivers/infiniband/sw/siw/siw_mem.h
+++ b/drivers/infiniband/sw/siw/siw_mem.h
@@ -61,7 +61,7 @@ static inline struct page *siw_get_upage(struct siw_umem *umem, u64 addr)
 		     chunk_idx = page_idx >> CHUNK_SHIFT,
 		     page_in_chunk = page_idx & ~CHUNK_MASK;
 
-	if (likely(page_idx < umem->num_pages))
+	if (likely(chunk_idx < umem->num_chunks))
 		return umem->page_chunk[chunk_idx].plist[page_in_chunk];
 
 	return NULL;
-- 
2.50.0