scsi: ipr: Error path locking fixes

This patch closes up some potential race conditions observed in the
error handling paths in ipr while debugging an issue resulting in a hang
with SATA error handling. These patches ensure we are holding the
correct lock when adding and removing commands from the free and pending
queues in some error scenarios.
Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Reviewed-by: Wendy Xiong <wenxiong@linux.vnet.ibm.com>
Tested-by: Wendy Xiong <wenxiong@linux.vnet.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/ipr.c

@@ -820,7 +820,7 @@ static int ipr_set_pcix_cmd_reg(struct ipr_ioa_cfg *ioa_cfg)
 }
 
 /**
- * ipr_sata_eh_done - done function for aborted SATA commands
+ * __ipr_sata_eh_done - done function for aborted SATA commands
  * @ipr_cmd:	ipr command struct
  *
  * This function is invoked for ops generated to SATA
@@ -829,7 +829,7 @@ static int ipr_set_pcix_cmd_reg(struct ipr_ioa_cfg *ioa_cfg)
  * Return value:
  * 	none
  **/
-static void ipr_sata_eh_done(struct ipr_cmnd *ipr_cmd)
+static void __ipr_sata_eh_done(struct ipr_cmnd *ipr_cmd)
 {
 	struct ata_queued_cmd *qc = ipr_cmd->qc;
 	struct ipr_sata_port *sata_port = qc->ap->private_data;
@@ -843,7 +843,27 @@ static void ipr_sata_eh_done(struct ipr_cmnd *ipr_cmd)
 }
 
 /**
- * ipr_scsi_eh_done - mid-layer done function for aborted ops
+ * ipr_sata_eh_done - done function for aborted SATA commands
+ * @ipr_cmd:	ipr command struct
+ *
+ * This function is invoked for ops generated to SATA
+ * devices which are being aborted.
+ *
+ * Return value:
+ * 	none
+ **/
+static void ipr_sata_eh_done(struct ipr_cmnd *ipr_cmd)
+{
+	struct ipr_hrr_queue *hrrq = ipr_cmd->hrrq;
+	unsigned long hrrq_flags;
+
+	spin_lock_irqsave(&hrrq->_lock, hrrq_flags);
+	__ipr_sata_eh_done(ipr_cmd);
+	spin_unlock_irqrestore(&hrrq->_lock, hrrq_flags);
+}
+
+/**
+ * __ipr_scsi_eh_done - mid-layer done function for aborted ops
  * @ipr_cmd:	ipr command struct
  *
  * This function is invoked by the interrupt handler for
@@ -852,7 +872,7 @@ static void ipr_sata_eh_done(struct ipr_cmnd *ipr_cmd)
  * Return value:
  * 	none
  **/
-static void ipr_scsi_eh_done(struct ipr_cmnd *ipr_cmd)
+static void __ipr_scsi_eh_done(struct ipr_cmnd *ipr_cmd)
 {
 	struct scsi_cmnd *scsi_cmd = ipr_cmd->scsi_cmd;
 
@@ -865,6 +885,26 @@ static void ipr_scsi_eh_done(struct ipr_cmnd *ipr_cmd)
 	list_add_tail(&ipr_cmd->queue, &ipr_cmd->hrrq->hrrq_free_q);
 }
 
+/**
+ * ipr_scsi_eh_done - mid-layer done function for aborted ops
+ * @ipr_cmd:	ipr command struct
+ *
+ * This function is invoked by the interrupt handler for
+ * ops generated by the SCSI mid-layer which are being aborted.
+ *
+ * Return value:
+ * 	none
+ **/
+static void ipr_scsi_eh_done(struct ipr_cmnd *ipr_cmd)
+{
+	unsigned long hrrq_flags;
+	struct ipr_hrr_queue *hrrq = ipr_cmd->hrrq;
+
+	spin_lock_irqsave(&hrrq->_lock, hrrq_flags);
+	__ipr_scsi_eh_done(ipr_cmd);
+	spin_unlock_irqrestore(&hrrq->_lock, hrrq_flags);
+}
+
 /**
  * ipr_fail_all_ops - Fails all outstanding ops.
  * @ioa_cfg:	ioa config struct
@@ -892,9 +932,9 @@ static void ipr_fail_all_ops(struct ipr_ioa_cfg *ioa_cfg)
 				cpu_to_be32(IPR_DRIVER_ILID);
 
 			if (ipr_cmd->scsi_cmd)
-				ipr_cmd->done = ipr_scsi_eh_done;
+				ipr_cmd->done = __ipr_scsi_eh_done;
 			else if (ipr_cmd->qc)
-				ipr_cmd->done = ipr_sata_eh_done;
+				ipr_cmd->done = __ipr_sata_eh_done;
 
 			ipr_trc_hook(ipr_cmd, IPR_TRACE_FINISH,
 				     IPR_IOASC_IOA_WAS_RESET);
@@ -5948,7 +5988,7 @@ static int ipr_build_ioadl(struct ipr_ioa_cfg *ioa_cfg,
 }
 
 /**
- * ipr_erp_done - Process completion of ERP for a device
+ * __ipr_erp_done - Process completion of ERP for a device
  * @ipr_cmd:		ipr command struct
  *
  * This function copies the sense buffer into the scsi_cmd
@@ -5957,7 +5997,7 @@ static int ipr_build_ioadl(struct ipr_ioa_cfg *ioa_cfg,
  * Return value:
  * 	nothing
  **/
-static void ipr_erp_done(struct ipr_cmnd *ipr_cmd)
+static void __ipr_erp_done(struct ipr_cmnd *ipr_cmd)
 {
 	struct scsi_cmnd *scsi_cmd = ipr_cmd->scsi_cmd;
 	struct ipr_resource_entry *res = scsi_cmd->device->hostdata;
@@ -5984,6 +6024,26 @@ static void ipr_erp_done(struct ipr_cmnd *ipr_cmd)
 	list_add_tail(&ipr_cmd->queue, &ipr_cmd->hrrq->hrrq_free_q);
 }
 
+/**
+ * ipr_erp_done - Process completion of ERP for a device
+ * @ipr_cmd:		ipr command struct
+ *
+ * This function copies the sense buffer into the scsi_cmd
+ * struct and pushes the scsi_done function.
+ *
+ * Return value:
+ * 	nothing
+ **/
+static void ipr_erp_done(struct ipr_cmnd *ipr_cmd)
+{
+	struct ipr_hrr_queue *hrrq = ipr_cmd->hrrq;
+	unsigned long hrrq_flags;
+
+	spin_lock_irqsave(&hrrq->_lock, hrrq_flags);
+	__ipr_erp_done(ipr_cmd);
+	spin_unlock_irqrestore(&hrrq->_lock, hrrq_flags);
+}
+
 /**
  * ipr_reinit_ipr_cmnd_for_erp - Re-initialize a cmnd block to be used for ERP
  * @ipr_cmd:	ipr command struct
@@ -6016,7 +6076,7 @@ static void ipr_reinit_ipr_cmnd_for_erp(struct ipr_cmnd *ipr_cmd)
 }
 
 /**
- * ipr_erp_request_sense - Send request sense to a device
+ * __ipr_erp_request_sense - Send request sense to a device
  * @ipr_cmd:	ipr command struct
  *
  * This function sends a request sense to a device as a result
@@ -6025,13 +6085,13 @@ static void ipr_reinit_ipr_cmnd_for_erp(struct ipr_cmnd *ipr_cmd)
  * Return value:
  * 	nothing
  **/
-static void ipr_erp_request_sense(struct ipr_cmnd *ipr_cmd)
+static void __ipr_erp_request_sense(struct ipr_cmnd *ipr_cmd)
 {
 	struct ipr_cmd_pkt *cmd_pkt = &ipr_cmd->ioarcb.cmd_pkt;
 	u32 ioasc = be32_to_cpu(ipr_cmd->s.ioasa.hdr.ioasc);
 
 	if (IPR_IOASC_SENSE_KEY(ioasc) > 0) {
-		ipr_erp_done(ipr_cmd);
+		__ipr_erp_done(ipr_cmd);
 		return;
 	}
 
@@ -6051,6 +6111,26 @@ static void ipr_erp_request_sense(struct ipr_cmnd *ipr_cmd)
 		   IPR_REQUEST_SENSE_TIMEOUT * 2);
 }
 
+/**
+ * ipr_erp_request_sense - Send request sense to a device
+ * @ipr_cmd:	ipr command struct
+ *
+ * This function sends a request sense to a device as a result
+ * of a check condition.
+ *
+ * Return value:
+ * 	nothing
+ **/
+static void ipr_erp_request_sense(struct ipr_cmnd *ipr_cmd)
+{
+	struct ipr_hrr_queue *hrrq = ipr_cmd->hrrq;
+	unsigned long hrrq_flags;
+
+	spin_lock_irqsave(&hrrq->_lock, hrrq_flags);
+	__ipr_erp_request_sense(ipr_cmd);
+	spin_unlock_irqrestore(&hrrq->_lock, hrrq_flags);
+}
+
 /**
  * ipr_erp_cancel_all - Send cancel all to a device
  * @ipr_cmd:	ipr command struct
@@ -6074,7 +6154,7 @@ static void ipr_erp_cancel_all(struct ipr_cmnd *ipr_cmd)
 	ipr_reinit_ipr_cmnd_for_erp(ipr_cmd);
 
 	if (!scsi_cmd->device->simple_tags) {
-		ipr_erp_request_sense(ipr_cmd);
+		__ipr_erp_request_sense(ipr_cmd);
 		return;
 	}
 
@@ -6294,7 +6374,7 @@ static void ipr_erp_start(struct ipr_ioa_cfg *ioa_cfg,
 	u32 masked_ioasc = ioasc & IPR_IOASC_IOASC_MASK;
 
 	if (!res) {
-		ipr_scsi_eh_done(ipr_cmd);
+		__ipr_scsi_eh_done(ipr_cmd);
 		return;
 	}