linux-kernel - [PATCH] scsi: mvsas: use struct

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Message-ID: <20190104214704.GA22286@embeddedor>
Date:   Fri, 4 Jan 2019 15:47:04 -0600
From:   "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To:     "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>
Cc:     linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org,
        "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Subject: [PATCH] scsi: mvsas: use struct_size() in kzalloc()

One of the more common cases of allocation size calculations is finding the
size of a structure that has a zero-sized array at the end, along with memory
for some number of elements for that array. For example:

struct foo {
    int stuff;
    void *entry[];
};

instance = kzalloc(sizeof(struct foo) + sizeof(void *) * count, GFP_KERNEL);

Instead of leaving these open-coded and prone to type mistakes, we can now
use the new struct_size() helper:

instance = kzalloc(struct_size(instance, entry, count), GFP_KERNEL);

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@...eddedor.com>
---
 drivers/scsi/mvsas/mv_init.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/scsi/mvsas/mv_init.c b/drivers/scsi/mvsas/mv_init.c
index 030d911ee374..cd6ba7ed0ab4 100644
--- a/drivers/scsi/mvsas/mv_init.c
+++ b/drivers/scsi/mvsas/mv_init.c
@@ -366,9 +366,9 @@ static struct mvs_info *mvs_pci_alloc(struct pci_dev *pdev,
 	struct mvs_info *mvi = NULL;
 	struct sas_ha_struct *sha = SHOST_TO_SAS_HA(shost);
 
-	mvi = kzalloc(sizeof(*mvi) +
-		(1L << mvs_chips[ent->driver_data].slot_width) *
-		sizeof(struct mvs_slot_info), GFP_KERNEL);
+	mvi = kzalloc(struct_size(mvi, slot_info,
+		      (1L << mvs_chips[ent->driver_data].slot_width)),
+		      GFP_KERNEL);
 	if (!mvi)
 		return NULL;
 
-- 
2.20.1