scsi: 3w-9xxx: Use flexible array members to avoid struct padding

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.

Link: https://lore.kernel.org/r/20210427235915.39211-2-samuel@sholland.org
Signed-off-by: Samuel Holland <samuel@sholland.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/3w-9xxx.c b/drivers/scsi/3w-9xxx.c
index 47028f5..c91e205 100644 (file)
--- 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 30109ae..23b312a 100644 (file)
--- 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 */