[SCSI] megaraid_sas: Add driver workaround for PERC5/1068 kdump kernel panic

The following patch for megaraid_sas adds a driver workaround for
PERC5/1068 based controller FW that keeps a command from the main
kernel that the driver cannot cancel which was causing a kernel panic
in shutdown of the kdump kernel.
Signed-off-by: Adam Radford <aradford@gmail.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

drivers/scsi/megaraid/megaraid_sas.h

@@ -139,6 +139,7 @@
 #define MFI_CMD_ABORT				0x06
 #define MFI_CMD_SMP				0x07
 #define MFI_CMD_STP				0x08
+#define MFI_CMD_INVALID				0xff
 
 #define MR_DCMD_CTRL_GET_INFO			0x01010000
 #define MR_DCMD_LD_GET_LIST			0x03010000

drivers/scsi/megaraid/megaraid_sas_base.c

@@ -215,6 +215,10 @@ megasas_return_cmd(struct megasas_instance *instance, struct megasas_cmd *cmd)
 
 	cmd->scmd = NULL;
 	cmd->frame_count = 0;
+	if ((instance->pdev->device != PCI_DEVICE_ID_LSI_FUSION) &&
+	    (instance->pdev->device != PCI_DEVICE_ID_LSI_INVADER) &&
+	    (reset_devices))
+		cmd->frame->hdr.cmd = MFI_CMD_INVALID;
 	list_add_tail(&cmd->list, &instance->cmd_pool);
 
 	spin_unlock_irqrestore(&instance->cmd_pool_lock, flags);
@@ -2165,7 +2169,16 @@ megasas_complete_cmd(struct megasas_instance *instance, struct megasas_cmd *cmd,
 		cmd->scmd->SCp.ptr = NULL;
 
 	switch (hdr->cmd) {
-
+	case MFI_CMD_INVALID:
+		/* Some older 1068 controller FW may keep a pended
+		   MR_DCMD_CTRL_EVENT_GET_INFO left over from the main kernel
+		   when booting the kdump kernel.  Ignore this command to
+		   prevent a kernel panic on shutdown of the kdump kernel. */
+		printk(KERN_WARNING "megaraid_sas: MFI_CMD_INVALID command "
+		       "completed.\n");
+		printk(KERN_WARNING "megaraid_sas: If you have a controller "
+		       "other than PERC5, please upgrade your firmware.\n");
+		break;
 	case MFI_CMD_PD_SCSI_IO:
 	case MFI_CMD_LD_SCSI_IO:
 
@@ -2934,6 +2947,10 @@ static int megasas_create_frame_pool(struct megasas_instance *instance)
 		memset(cmd->frame, 0, total_sz);
 		cmd->frame->io.context = cmd->index;
 		cmd->frame->io.pad_0 = 0;
+		if ((instance->pdev->device != PCI_DEVICE_ID_LSI_FUSION) &&
+		    (instance->pdev->device != PCI_DEVICE_ID_LSI_INVADER) &&
+		    (reset_devices))
+			cmd->frame->hdr.cmd = MFI_CMD_INVALID;
 	}
 
 	return 0;