scsi: megaraid_sas: Use struct_size() helper

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 <[email protected]>

---
 drivers/scsi/megaraid/megaraid_sas_fusion.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

drivers/scsi/megaraid/megaraid_sas_fusion.c +2 -5

index a25b6b4b6548..56bd524dddbf 100644
@@ -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

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.