[SCSI] hide EH backup data outside the scsi_cmnd

Currently struct scsi_cmnd has various fields that are used to backup
original data after the corresponding fields have been overridden for
EH commands. This means drivers can easily get at it and misuse it.
Due to the old_ naming this doesn't happen for most of them, but two
that have different names have been used wrong a lot (see previous
patch). Another downside is that they unessecarily bloat the scsi_cmnd
size.

This patch moves them onstack in scsi_send_eh_cmnd to fix those two
issues aswell as allowing future EH fixes like moving the EH command
submissions to use SG lists like everything else.

Signed-off-by: Christoph Hellwig <[e-mail]>
Signed-off-by: James Bottomley <[e-mail]>

drivers/scsi/aha152x.c

···
 	DECLARE_MUTEX_LOCKED(sem);
 	struct timer_list timer;
 	int ret, issued, disconnected;
+	unsigned char old_cmd_len = SCpnt->cmd_len;
+	unsigned short old_use_sg = SCpnt->use_sg;
+	void *old_buffer = SCpnt->request_buffer;
+	unsigned old_bufflen = SCpnt->request_bufflen;
 	unsigned long flags;
 
 #if defined(AHA152X_DEBUG)
···
 	add_timer(&timer);
 	down(&sem);
 	del_timer(&timer);
-	
-	SCpnt->cmd_len         = SCpnt->old_cmd_len;
-	SCpnt->use_sg          = SCpnt->old_use_sg;
-  	SCpnt->request_buffer  = SCpnt->buffer;
-       	SCpnt->request_bufflen = SCpnt->bufflen;
+
+	SCpnt->cmd_len         = old_cmd_len;
+	SCpnt->use_sg          = old_use_sg;
+  	SCpnt->request_buffer  = old_buffer;
+       	SCpnt->request_bufflen = old_bufflen;
 
 	DO_LOCK(flags);
 

drivers/scsi/scsi.c

···
 			if (level > 3) {
 				printk(KERN_INFO "buffer = 0x%p, bufflen = %d,"
 				       " done = 0x%p, queuecommand 0x%p\n",
-					cmd->buffer, cmd->bufflen,
+					cmd->request_buffer, cmd->request_bufflen,
 					cmd->done,
 					sdev->host->hostt->queuecommand);
 
···
  */
 int scsi_retry_command(struct scsi_cmnd *cmd)
 {
-	/*
-	 * Restore the SCSI command state.
-	 */
-	scsi_setup_cmd_retry(cmd);
-
         /*
          * Zero the sense information from the last time we tried
          * this command.
···
 				"Notifying upper driver of completion "
 				"(result %x)\n", cmd->result));
 
-	/*
-	 * We can get here with use_sg=0, causing a panic in the upper level
-	 */
-	cmd->use_sg = cmd->old_use_sg;
 	cmd->done(cmd);
 }
 EXPORT_SYMBOL(scsi_finish_command);

drivers/scsi/scsi_error.c

···
  * Return value:
  *    SUCCESS or FAILED or NEEDS_RETRY
  **/
-static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd, int timeout)
+static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd, int timeout, int copy_sense)
 {
 	struct scsi_device *sdev = scmd->device;
 	struct Scsi_Host *shost = sdev->host;
+	int old_result = scmd->result;
 	DECLARE_COMPLETION(done);
 	unsigned long timeleft;
 	unsigned long flags;
+	unsigned char old_cmnd[MAX_COMMAND_SIZE];
+	enum dma_data_direction old_data_direction;
+	unsigned short old_use_sg;
+	unsigned char old_cmd_len;
+	unsigned old_bufflen;
+	void *old_buffer;
 	int rtn;
+
+	/*
+	 * We need saved copies of a number of fields - this is because
+	 * error handling may need to overwrite these with different values
+	 * to run different commands, and once error handling is complete,
+	 * we will need to restore these values prior to running the actual
+	 * command.
+	 */
+	old_buffer = scmd->request_buffer;
+	old_bufflen = scmd->request_bufflen;
+	memcpy(old_cmnd, scmd->cmnd, sizeof(scmd->cmnd));
+	old_data_direction = scmd->sc_data_direction;
+	old_cmd_len = scmd->cmd_len;
+	old_use_sg = scmd->use_sg;
+
+	if (copy_sense) {
+		int gfp_mask = GFP_ATOMIC;
+
+		if (shost->hostt->unchecked_isa_dma)
+			gfp_mask |= __GFP_DMA;
+
+		scmd->sc_data_direction = DMA_FROM_DEVICE;
+		scmd->request_bufflen = 252;
+		scmd->request_buffer = kzalloc(scmd->request_bufflen, gfp_mask);
+		if (!scmd->request_buffer)
+			return FAILED;
+	} else {
+		scmd->request_buffer = NULL;
+		scmd->request_bufflen = 0;
+		scmd->sc_data_direction = DMA_NONE;
+	}
+
+	scmd->underflow = 0;
+	scmd->use_sg = 0;
+	scmd->cmd_len = COMMAND_SIZE(scmd->cmnd[0]);
 
 	if (sdev->scsi_level <= SCSI_2)
 		scmd->cmnd[1] = (scmd->cmnd[1] & 0x1f) |
 			(sdev->lun << 5 & 0xe0);
+
+	/*
+	 * Zero the sense buffer.  The scsi spec mandates that any
+	 * untransferred sense data should be interpreted as being zero.
+	 */
+	memset(scmd->sense_buffer, 0, sizeof(scmd->sense_buffer));
 
 	shost->eh_action = &done;
 
···
 		rtn = FAILED;
 	}
 
+
+	/*
+	 * Last chance to have valid sense data.
+	 */
+	if (copy_sense) {
+		if (!SCSI_SENSE_VALID(scmd)) {
+			memcpy(scmd->sense_buffer, scmd->request_buffer,
+			       sizeof(scmd->sense_buffer));
+		}
+		kfree(scmd->request_buffer);
+	}
+
+
+	/*
+	 * Restore original data
+	 */
+	scmd->request_buffer = old_buffer;
+	scmd->request_bufflen = old_bufflen;
+	memcpy(scmd->cmnd, old_cmnd, sizeof(scmd->cmnd));
+	scmd->sc_data_direction = old_data_direction;
+	scmd->cmd_len = old_cmd_len;
+	scmd->use_sg = old_use_sg;
+	scmd->result = old_result;
 	return rtn;
 }
 
···
 static int scsi_request_sense(struct scsi_cmnd *scmd)
 {
 	static unsigned char generic_sense[6] =
-	{REQUEST_SENSE, 0, 0, 0, 252, 0};
-	unsigned char *scsi_result;
-	int saved_result;
-	int rtn;
+		{REQUEST_SENSE, 0, 0, 0, 252, 0};
 
 	memcpy(scmd->cmnd, generic_sense, sizeof(generic_sense));
-
-	scsi_result = kmalloc(252, GFP_ATOMIC | ((scmd->device->host->hostt->unchecked_isa_dma) ? __GFP_DMA : 0));
-
-
-	if (unlikely(!scsi_result)) {
-		printk(KERN_ERR "%s: cannot allocate scsi_result.\n",
-		       __FUNCTION__);
-		return FAILED;
-	}
-
-	/*
-	 * zero the sense buffer.  some host adapters automatically always
-	 * request sense, so it is not a good idea that
-	 * scmd->request_buffer and scmd->sense_buffer point to the same
-	 * address (db).  0 is not a valid sense code. 
-	 */
-	memset(scmd->sense_buffer, 0, sizeof(scmd->sense_buffer));
-	memset(scsi_result, 0, 252);
-
-	saved_result = scmd->result;
-	scmd->request_buffer = scsi_result;
-	scmd->request_bufflen = 252;
-	scmd->use_sg = 0;
-	scmd->cmd_len = COMMAND_SIZE(scmd->cmnd[0]);
-	scmd->sc_data_direction = DMA_FROM_DEVICE;
-	scmd->underflow = 0;
-
-	rtn = scsi_send_eh_cmnd(scmd, SENSE_TIMEOUT);
-
-	/* last chance to have valid sense data */
-	if(!SCSI_SENSE_VALID(scmd)) {
-		memcpy(scmd->sense_buffer, scmd->request_buffer,
-		       sizeof(scmd->sense_buffer));
-	}
-
-	kfree(scsi_result);
-
-	/*
-	 * when we eventually call scsi_finish, we really wish to complete
-	 * the original request, so let's restore the original data. (db)
-	 */
-	scsi_setup_cmd_retry(scmd);
-	scmd->result = saved_result;
-	return rtn;
+	return scsi_send_eh_cmnd(scmd, SENSE_TIMEOUT, 1);
 }
 
 /**
···
 {
 	scmd->device->host->host_failed--;
 	scmd->eh_eflags = 0;
-
-	/*
-	 * set this back so that the upper level can correctly free up
-	 * things.
-	 */
-	scsi_setup_cmd_retry(scmd);
 	list_move_tail(&scmd->eh_entry, done_q);
 }
 EXPORT_SYMBOL(scsi_eh_finish_cmd);
···
 {
 	static unsigned char tur_command[6] = {TEST_UNIT_READY, 0, 0, 0, 0, 0};
 	int retry_cnt = 1, rtn;
-	int saved_result;
 
 retry_tur:
 	memcpy(scmd->cmnd, tur_command, sizeof(tur_command));
 
-	/*
-	 * zero the sense buffer.  the scsi spec mandates that any
-	 * untransferred sense data should be interpreted as being zero.
-	 */
-	memset(scmd->sense_buffer, 0, sizeof(scmd->sense_buffer));
 
-	saved_result = scmd->result;
-	scmd->request_buffer = NULL;
-	scmd->request_bufflen = 0;
-	scmd->use_sg = 0;
-	scmd->cmd_len = COMMAND_SIZE(scmd->cmnd[0]);
-	scmd->underflow = 0;
-	scmd->sc_data_direction = DMA_NONE;
+	rtn = scsi_send_eh_cmnd(scmd, SENSE_TIMEOUT, 0);
 
-	rtn = scsi_send_eh_cmnd(scmd, SENSE_TIMEOUT);
-
-	/*
-	 * when we eventually call scsi_finish, we really wish to complete
-	 * the original request, so let's restore the original data. (db)
-	 */
-	scsi_setup_cmd_retry(scmd);
-	scmd->result = saved_result;
-
-	/*
-	 * hey, we are done.  let's look to see what happened.
-	 */
 	SCSI_LOG_ERROR_RECOVERY(3, printk("%s: scmd %p rtn %x\n",
 		__FUNCTION__, scmd, rtn));
-	if (rtn == SUCCESS)
-		return 0;
-	else if (rtn == NEEDS_RETRY) {
+
+	switch (rtn) {
+	case NEEDS_RETRY:
 		if (retry_cnt--)
 			goto retry_tur;
+		/*FALLTHRU*/
+	case SUCCESS:
 		return 0;
+	default:
+		return 1;
 	}
-	return 1;
 }
 
 /**
···
 static int scsi_eh_try_stu(struct scsi_cmnd *scmd)
 {
 	static unsigned char stu_command[6] = {START_STOP, 0, 0, 0, 1, 0};
-	int rtn;
-	int saved_result;
 
-	if (!scmd->device->allow_restart)
-		return 1;
+	if (scmd->device->allow_restart) {
+		int rtn;
 
-	memcpy(scmd->cmnd, stu_command, sizeof(stu_command));
+		memcpy(scmd->cmnd, stu_command, sizeof(stu_command));
+		rtn = scsi_send_eh_cmnd(scmd, START_UNIT_TIMEOUT, 0);
+		if (rtn == SUCCESS)
+			return 0;
+	}
 
-	/*
-	 * zero the sense buffer.  the scsi spec mandates that any
-	 * untransferred sense data should be interpreted as being zero.
-	 */
-	memset(scmd->sense_buffer, 0, sizeof(scmd->sense_buffer));
-
-	saved_result = scmd->result;
-	scmd->request_buffer = NULL;
-	scmd->request_bufflen = 0;
-	scmd->use_sg = 0;
-	scmd->cmd_len = COMMAND_SIZE(scmd->cmnd[0]);
-	scmd->underflow = 0;
-	scmd->sc_data_direction = DMA_NONE;
-
-	rtn = scsi_send_eh_cmnd(scmd, START_UNIT_TIMEOUT);
-
-	/*
-	 * when we eventually call scsi_finish, we really wish to complete
-	 * the original request, so let's restore the original data. (db)
-	 */
-	scsi_setup_cmd_retry(scmd);
-	scmd->result = saved_result;
-
-	/*
-	 * hey, we are done.  let's look to see what happened.
-	 */
-	SCSI_LOG_ERROR_RECOVERY(3, printk("%s: scmd %p rtn %x\n",
-		__FUNCTION__, scmd, rtn));
-	if (rtn == SUCCESS)
-		return 0;
 	return 1;
 }
 
···
     
 	scmd->scsi_done		= scsi_reset_provider_done_command;
 	scmd->done			= NULL;
-	scmd->buffer			= NULL;
-	scmd->bufflen			= 0;
 	scmd->request_buffer		= NULL;
 	scmd->request_bufflen		= 0;
 

drivers/scsi/scsi_lib.c

···
  *
  * Arguments:   cmd	- command that is ready to be queued.
  *
- * Returns:     Nothing
- *
  * Notes:       This function has the job of initializing a number of
  *              fields related to error handling.   Typically this will
  *              be called once for each command, as required.
  */
-static int scsi_init_cmd_errh(struct scsi_cmnd *cmd)
+static void scsi_init_cmd_errh(struct scsi_cmnd *cmd)
 {
 	cmd->serial_number = 0;
-
 	memset(cmd->sense_buffer, 0, sizeof cmd->sense_buffer);
-
 	if (cmd->cmd_len == 0)
 		cmd->cmd_len = COMMAND_SIZE(cmd->cmnd[0]);
-
-	/*
-	 * We need saved copies of a number of fields - this is because
-	 * error handling may need to overwrite these with different values
-	 * to run different commands, and once error handling is complete,
-	 * we will need to restore these values prior to running the actual
-	 * command.
-	 */
-	cmd->old_use_sg = cmd->use_sg;
-	cmd->old_cmd_len = cmd->cmd_len;
-	cmd->sc_old_data_direction = cmd->sc_data_direction;
-	cmd->old_underflow = cmd->underflow;
-	memcpy(cmd->data_cmnd, cmd->cmnd, sizeof(cmd->cmnd));
-	cmd->buffer = cmd->request_buffer;
-	cmd->bufflen = cmd->request_bufflen;
-
-	return 1;
-}
-
-/*
- * Function:   scsi_setup_cmd_retry()
- *
- * Purpose:    Restore the command state for a retry
- *
- * Arguments:  cmd	- command to be restored
- *
- * Returns:    Nothing
- *
- * Notes:      Immediately prior to retrying a command, we need
- *             to restore certain fields that we saved above.
- */
-void scsi_setup_cmd_retry(struct scsi_cmnd *cmd)
-{
-	memcpy(cmd->cmnd, cmd->data_cmnd, sizeof(cmd->data_cmnd));
-	cmd->request_buffer = cmd->buffer;
-	cmd->request_bufflen = cmd->bufflen;
-	cmd->use_sg = cmd->old_use_sg;
-	cmd->cmd_len = cmd->old_cmd_len;
-	cmd->sc_data_direction = cmd->sc_old_data_direction;
-	cmd->underflow = cmd->old_underflow;
 }
 
 void scsi_device_unbusy(struct scsi_device *sdev)
···
  */
 static void scsi_release_buffers(struct scsi_cmnd *cmd)
 {
-	struct request *req = cmd->request;
-
-	/*
-	 * Free up any indirection buffers we allocated for DMA purposes. 
-	 */
 	if (cmd->use_sg)
 		scsi_free_sgtable(cmd->request_buffer, cmd->sglist_len);
-	else if (cmd->request_buffer != req->buffer)
-		kfree(cmd->request_buffer);
 
 	/*
 	 * Zero these out.  They now point to freed memory, and it is
 	 * dangerous to hang onto the pointers.
 	 */
-	cmd->buffer  = NULL;
-	cmd->bufflen = 0;
 	cmd->request_buffer = NULL;
 	cmd->request_bufflen = 0;
 }
···
 void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
 {
 	int result = cmd->result;
-	int this_count = cmd->bufflen;
+	int this_count = cmd->request_bufflen;
 	request_queue_t *q = cmd->device->request_queue;
 	struct request *req = cmd->request;
 	int clear_errors = 1;
···
 	int sense_valid = 0;
 	int sense_deferred = 0;
 
-	/*
-	 * Free up any indirection buffers we allocated for DMA purposes. 
-	 * For the case of a READ, we need to copy the data out of the
-	 * bounce buffer and into the real buffer.
-	 */
-	if (cmd->use_sg)
-		scsi_free_sgtable(cmd->buffer, cmd->sglist_len);
-	else if (cmd->buffer != req->buffer) {
-		if (rq_data_dir(req) == READ) {
-			unsigned long flags;
-			char *to = bio_kmap_irq(req->bio, &flags);
-			memcpy(to, cmd->buffer, cmd->bufflen);
-			bio_kunmap_irq(to, &flags);
-		}
-		kfree(cmd->buffer);
-	}
+	scsi_release_buffers(cmd);
 
 	if (result) {
 		sense_valid = scsi_command_normalize_sense(cmd, &sshdr);
 		if (sense_valid)
 			sense_deferred = scsi_sense_is_deferred(&sshdr);
 	}
+
 	if (blk_pc_request(req)) { /* SG_IO ioctl from block level */
 		req->errors = result;
 		if (result) {
···
 		} else
 			req->data_len = cmd->resid;
 	}
-
-	/*
-	 * Zero these out.  They now point to freed memory, and it is
-	 * dangerous to hang onto the pointers.
-	 */
-	cmd->buffer  = NULL;
-	cmd->bufflen = 0;
-	cmd->request_buffer = NULL;
-	cmd->request_bufflen = 0;
 
 	/*
 	 * Next deal with any sectors which we were able to correctly
···
 			if (!(req->flags & REQ_QUIET)) {
 				scmd_printk(KERN_INFO, cmd,
 					    "Volume overflow, CDB: ");
-				__scsi_print_command(cmd->data_cmnd);
+				__scsi_print_command(cmd->cmnd);
 				scsi_print_sense("", cmd);
 			}
 			/* See SSC3rXX or current. */
···
 	 * successfully. Since this is a REQ_BLOCK_PC command the
 	 * caller should check the request's errors value
 	 */
-	scsi_io_completion(cmd, cmd->bufflen);
+	scsi_io_completion(cmd, cmd->request_bufflen);
 }
 
 static void scsi_setup_blk_pc_cmnd(struct scsi_cmnd *cmd)

drivers/scsi/scsi_priv.h

···
 
 /* scsi_lib.c */
 extern int scsi_maybe_unblock_host(struct scsi_device *sdev);
-extern void scsi_setup_cmd_retry(struct scsi_cmnd *cmd);
 extern void scsi_device_unbusy(struct scsi_device *sdev);
 extern int scsi_queue_insert(struct scsi_cmnd *cmd, int reason);
 extern void scsi_next_command(struct scsi_cmnd *cmd);

drivers/scsi/sd.c

···
 		SCpnt->cmnd[4] = (unsigned char) this_count;
 		SCpnt->cmnd[5] = 0;
 	}
-	SCpnt->request_bufflen = SCpnt->bufflen =
-			this_count * sdp->sector_size;
+	SCpnt->request_bufflen = this_count * sdp->sector_size;
 
 	/*
 	 * We shouldn't disconnect in the middle of a sector, so with a dumb

drivers/scsi/sr.c

···
 				"mismatch count %d, bytes %d\n",
 				size, SCpnt->request_bufflen);
 			if (SCpnt->request_bufflen > size)
-				SCpnt->request_bufflen = SCpnt->bufflen = size;
+				SCpnt->request_bufflen = size;
 		}
 	}
 
···
 
 	if (this_count > 0xffff) {
 		this_count = 0xffff;
-		SCpnt->request_bufflen = SCpnt->bufflen =
-				this_count * s_size;
+		SCpnt->request_bufflen = this_count * s_size;
 	}
 
 	SCpnt->cmnd[2] = (unsigned char) (block >> 24) & 0xff;

include/scsi/scsi_cmnd.h

···
 	int timeout_per_command;
 
 	unsigned char cmd_len;
-	unsigned char old_cmd_len;
 	enum dma_data_direction sc_data_direction;
-	enum dma_data_direction sc_old_data_direction;
 
 	/* These elements define the operation we are about to perform */
 #define MAX_COMMAND_SIZE	16
···
 	void *request_buffer;		/* Actual requested buffer */
 
 	/* These elements define the operation we ultimately want to perform */
-	unsigned char data_cmnd[MAX_COMMAND_SIZE];
-	unsigned short old_use_sg;	/* We save  use_sg here when requesting
-					 * sense info */
 	unsigned short use_sg;	/* Number of pieces of scatter-gather */
 	unsigned short sglist_len;	/* size of malloc'd scatter-gather list */
-	unsigned bufflen;	/* Size of data buffer */
-	void *buffer;		/* Data buffer */
 
 	unsigned underflow;	/* Return error if less than
 				   this amount is transferred */
-	unsigned old_underflow;	/* save underflow here when reusing the
-				 * command for error handling */
 
 	unsigned transfersize;	/* How much we are guaranteed to
 				   transfer with each SCSI transfer