[PATCH v5 1/3] scsi: 3w-9xxx: Use flexible array members to avoid struct padding

Samuel Holland
2021-04-27T23:59:25Z

In preparation for removing the "#pragma pack(1)" from the driver, fix
all instances where a trailing array member could be replaced by a
flexible array member. Since a flexible array member has zero size, it
introduces no padding, whether or not the struct is packed.

Signed-off-by: Samuel Holland <samuel@sholland.org>
---
drivers/scsi/3w-9xxx.c | 16 ++++++++++------
drivers/scsi/3w-9xxx.h | 4 ++--
2 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/drivers/scsi/3w-9xxx.c b/drivers/scsi/3w-9xxx.c
index b96e82de4237..36564943591e 100644
--- a/drivers/scsi/3w-9xxx.c
+++ b/drivers/scsi/3w-9xxx.c
@@ -676,7 +676,9 @@ static long twa_chrdev_ioctl(struct file *file, unsigned int cmd, unsigned long
data_buffer_length_adjusted = (driver_command.buffer_length + 511) & ~511;

/* Now allocate ioctl buf memory */
- cpu_addr = dma_alloc_coherent(&tw_dev->tw_pci_dev->dev, data_buffer_length_adjusted+sizeof(TW_Ioctl_Buf_Apache) - 1, &dma_handle, GFP_KERNEL);
+ cpu_addr = dma_alloc_coherent(&tw_dev->tw_pci_dev->dev,
+ sizeof(TW_Ioctl_Buf_Apache) + data_buffer_length_adjusted,
+ &dma_handle, GFP_KERNEL);
if (!cpu_addr) {
retval = TW_IOCTL_ERROR_OS_ENOMEM;
goto out2;
@@ -685,7 +687,7 @@ static long twa_chrdev_ioctl(struct file *file, unsigned int cmd, unsigned long
tw_ioctl = (TW_Ioctl_Buf_Apache *)cpu_addr;

/* Now copy down the entire ioctl */
- if (copy_from_user(tw_ioctl, argp, driver_command.buffer_length + sizeof(TW_Ioctl_Buf_Apache) - 1))
+ if (copy_from_user(tw_ioctl, argp, sizeof(TW_Ioctl_Buf_Apache) + driver_command.buffer_length))
goto out3;

/* See which ioctl we are doing */
@@ -867,11 +869,13 @@ static long twa_chrdev_ioctl(struct file *file, unsigned int cmd, unsigned long
}

/* Now copy the entire response to userspace */
- if (copy_to_user(argp, tw_ioctl, sizeof(TW_Ioctl_Buf_Apache) + driver_command.buffer_length - 1) == 0)
+ if (copy_to_user(argp, tw_ioctl, sizeof(TW_Ioctl_Buf_Apache) + driver_command.buffer_length) == 0)
retval = 0;
out3:
/* Now free ioctl buf memory */
- dma_free_coherent(&tw_dev->tw_pci_dev->dev, data_buffer_length_adjusted+sizeof(TW_Ioctl_Buf_Apache) - 1, cpu_addr, dma_handle);
+ dma_free_coherent(&tw_dev->tw_pci_dev->dev,
+ sizeof(TW_Ioctl_Buf_Apache) + data_buffer_length_adjusted,
+ cpu_addr, dma_handle);
out2:
mutex_unlock(&tw_dev->ioctl_lock);
out:
@@ -1392,7 +1396,7 @@ static void twa_load_sgl(TW_Device_Extension *tw_dev, TW_Command_Full *full_comm
newcommand->request_id__lunl =
cpu_to_le16(TW_REQ_LUN_IN(TW_LUN_OUT(newcommand->request_id__lunl), request_id));
if (length) {
- newcommand->sg_list[0].address = TW_CPU_TO_SGL(dma_handle + sizeof(TW_Ioctl_Buf_Apache) - 1);
+ newcommand->sg_list[0].address = TW_CPU_TO_SGL(dma_handle + sizeof(TW_Ioctl_Buf_Apache));
newcommand->sg_list[0].length = cpu_to_le32(length);
}
newcommand->sgl_entries__lunh =
@@ -1407,7 +1411,7 @@ static void twa_load_sgl(TW_Device_Extension *tw_dev, TW_Command_Full *full_comm
sgl = (TW_SG_Entry *)((u32 *)oldcommand+oldcommand->size - (sizeof(TW_SG_Entry)/4) + pae);
else
sgl = (TW_SG_Entry *)((u32 *)oldcommand+TW_SGL_OUT(oldcommand->opcode__sgloffset));
- sgl->address = TW_CPU_TO_SGL(dma_handle + sizeof(TW_Ioctl_Buf_Apache) - 1);
+ sgl->address = TW_CPU_TO_SGL(dma_handle + sizeof(TW_Ioctl_Buf_Apache));
sgl->length = cpu_to_le32(length);

oldcommand->size += pae;
diff --git a/drivers/scsi/3w-9xxx.h b/drivers/scsi/3w-9xxx.h
index d3f479324527..f93795164d7d 100644
--- a/drivers/scsi/3w-9xxx.h
+++ b/drivers/scsi/3w-9xxx.h
@@ -602,7 +602,7 @@ typedef struct TAG_TW_Ioctl_Apache {
TW_Ioctl_Driver_Command driver_command;
char padding[488];
TW_Command_Full firmware_command;
- char data_buffer[1];
+ char data_buffer[];
} TW_Ioctl_Buf_Apache;

/* Lock structure for ioctl get/release lock */
@@ -618,7 +618,7 @@ typedef struct {
unsigned short parameter_id;
unsigned short parameter_size_bytes;
unsigned short actual_parameter_size_bytes;
- unsigned char data[1];
+ unsigned char data[];
} TW_Param_Apache, *PTW_Param_Apache;

/* Response queue */
--
2.26.3