[PATCH] scsi: megaraid_sas: Use struct_size() helper

From: Gustavo A. R. Silva
Date: Fri Jun 07 2019 - 14:45:14 EST


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 MR_PD_CFG_SEQ_NUM_SYNC {
...
struct MR_PD_CFG_SEQ seq[1];
} __packed;

Make use of the struct_size() helper instead of an open-coded version
in order to avoid any potential type mistakes.

So, replace the following form:

sizeof(struct MR_PD_CFG_SEQ_NUM_SYNC) + (sizeof(struct MR_PD_CFG_SEQ) * (MAX_PHYSICAL_DEVICES - 1))

with:

struct_size(pd_sync, seq, MAX_PHYSICAL_DEVICES - 1)

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx>
---
drivers/scsi/megaraid/megaraid_sas_fusion.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/scsi/megaraid/megaraid_sas_fusion.c b/drivers/scsi/megaraid/megaraid_sas_fusion.c
index a25b6b4b6548..56bd524dddbf 100644
--- a/drivers/scsi/megaraid/megaraid_sas_fusion.c
+++ b/drivers/scsi/megaraid/megaraid_sas_fusion.c
@@ -1191,7 +1191,7 @@ megasas_ioc_init_fusion(struct megasas_instance *instance)
int
megasas_sync_pd_seq_num(struct megasas_instance *instance, bool pend) {
int ret = 0;
- u32 pd_seq_map_sz;
+ size_t pd_seq_map_sz;
struct megasas_cmd *cmd;
struct megasas_dcmd_frame *dcmd;
struct fusion_context *fusion = instance->ctrl_context;
@@ -1200,9 +1200,7 @@ megasas_sync_pd_seq_num(struct megasas_instance *instance, bool pend) {

pd_sync = (void *)fusion->pd_seq_sync[(instance->pd_seq_map_id & 1)];
pd_seq_h = fusion->pd_seq_phys[(instance->pd_seq_map_id & 1)];
- pd_seq_map_sz = sizeof(struct MR_PD_CFG_SEQ_NUM_SYNC) +
- (sizeof(struct MR_PD_CFG_SEQ) *
- (MAX_PHYSICAL_DEVICES - 1));
+ pd_seq_map_sz = struct_size(pd_sync, seq, MAX_PHYSICAL_DEVICES - 1);

cmd = megasas_get_cmd(instance);
if (!cmd) {
--
2.21.0