[PATCH 1/2][next] scsi: hptiop: Replace one-element array with flexible-array member

From: Gustavo A. R. Silva
Date: Thu Sep 22 2022 - 12:53:42 EST


One-element arrays are deprecated, and we are replacing them with flexible
array members instead. So, replace one-element array with flexible-array
member in struct hpt_iop_request_scsi_command and refactor the rest of the
code, accordingly.

The following pieces of code suggest that the one element of array sg_list
in struct hpt_iop_request_scsi_command is not taken into account when
calculating the total size for both struct hpt_iop_request_scsi_command
and the maximum number of elements sg_list will contain:

1047 req->header.size = cpu_to_le32(
1048 sizeof(struct hpt_iop_request_scsi_command)
1049 - sizeof(struct hpt_iopsg)
1050 + sg_count * sizeof(struct hpt_iopsg));

1400 req_size = sizeof(struct hpt_iop_request_scsi_command) 1401 + sizeof(struct hpt_iopsg) * (hba->max_sg_descriptors - 1);

So it's safe to replace the one-element array with a flexible-array
member and update the code above, accordingly: now we don't need to
subtract sizeof(struct hpt_iopsg) from sizeof(struct hpt_iop_request_scsi_command)
because this is implicitly done by the flex-array transformation.

Link: https://github.com/KSPP/linux/issues/79
Link: https://github.com/KSPP/linux/issues/205
Signed-off-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx>
---
drivers/scsi/hptiop.c | 3 +--
drivers/scsi/hptiop.h | 2 +-
2 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/scsi/hptiop.c b/drivers/scsi/hptiop.c
index f18b770626e6..cfc6546e35a6 100644
--- a/drivers/scsi/hptiop.c
+++ b/drivers/scsi/hptiop.c
@@ -1046,7 +1046,6 @@ static int hptiop_queuecommand_lck(struct scsi_cmnd *scp)
req->lun = scp->device->lun;
req->header.size = cpu_to_le32(
sizeof(struct hpt_iop_request_scsi_command)
- - sizeof(struct hpt_iopsg)
+ sg_count * sizeof(struct hpt_iopsg));

memcpy(req->cdb, scp->cmnd, sizeof(req->cdb));
@@ -1398,7 +1397,7 @@ static int hptiop_probe(struct pci_dev *pcidev, const struct pci_device_id *id)
host->max_cmd_len = 16;

req_size = sizeof(struct hpt_iop_request_scsi_command)
- + sizeof(struct hpt_iopsg) * (hba->max_sg_descriptors - 1);
+ + sizeof(struct hpt_iopsg) * hba->max_sg_descriptors;
if ((req_size & 0x1f) != 0)
req_size = (req_size + 0x1f) & ~0x1f;

diff --git a/drivers/scsi/hptiop.h b/drivers/scsi/hptiop.h
index 363d5a16243f..ef2f2aca598c 100644
--- a/drivers/scsi/hptiop.h
+++ b/drivers/scsi/hptiop.h
@@ -228,7 +228,7 @@ struct hpt_iop_request_scsi_command {
u8 pad1;
u8 cdb[16];
__le32 dataxfer_length;
- struct hpt_iopsg sg_list[1];
+ struct hpt_iopsg sg_list[];
};

struct hpt_iop_request_ioctl_command {
--
2.34.1