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From:   Christophe JAILLET <christophe.jaillet@wanadoo.fr>
To:     Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com>,
        Jason Gunthorpe <jgg@ziepe.ca>,
        Leon Romanovsky <leon@kernel.org>
Cc:     linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org,
        Christophe JAILLET <christophe.jaillet@wanadoo.fr>,
        linux-rdma@vger.kernel.org
Subject: [PATCH v2] IB/hfi1: Use struct_size()
Date:   Sat, 22 Jul 2023 18:47:24 +0200
Message-Id: <f4618a67d5ae0a30eb3f2b4558c8cc790feed79a.1690044376.git.christophe.jaillet@wanadoo.fr>
MIME-Version: 1.0
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Precedence: bulk

Use struct_size() instead of hand-writing it, when allocating a structure
with a flex array.

This is less verbose, more robust and more informative.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
---
It will also be helpful if the __counted_by() annotation is added with a
Coccinelle script such as:
   https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git/commit/?h=devel/counted_by&id=adc5b3cb48a049563dc673f348eab7b6beba8a9b


Change in v2: use struct_size() in another place just a few line below.
---
 drivers/infiniband/hw/hfi1/pio.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/drivers/infiniband/hw/hfi1/pio.c b/drivers/infiniband/hw/hfi1/pio.c
index 62e7dc9bea7b..dfea53e0fdeb 100644
--- a/drivers/infiniband/hw/hfi1/pio.c
+++ b/drivers/infiniband/hw/hfi1/pio.c
@@ -1893,9 +1893,7 @@ int pio_map_init(struct hfi1_devdata *dd, u8 port, u8 num_vls, u8 *vl_scontexts)
 			vl_scontexts[i] = sc_per_vl + (extra > 0 ? 1 : 0);
 	}
 	/* build new map */
-	newmap = kzalloc(sizeof(*newmap) +
-			 roundup_pow_of_two(num_vls) *
-			 sizeof(struct pio_map_elem *),
+	newmap = kzalloc(struct_size(newmap, map, roundup_pow_of_two(num_vls)),
 			 GFP_KERNEL);
 	if (!newmap)
 		goto bail;
@@ -1910,9 +1908,8 @@ int pio_map_init(struct hfi1_devdata *dd, u8 port, u8 num_vls, u8 *vl_scontexts)
 			int sz = roundup_pow_of_two(vl_scontexts[i]);
 
 			/* only allocate once */
-			newmap->map[i] = kzalloc(sizeof(*newmap->map[i]) +
-						 sz * sizeof(struct
-							     send_context *),
+			newmap->map[i] = kzalloc(struct_size(newmap->map[i],
+							     ksc, sz),
 						 GFP_KERNEL);
 			if (!newmap->map[i])
 				goto bail;
-- 
2.34.1