[PATCH 1/4] pm80xx: make mpi_build_cmd locking consistent

[Viswas G <Viswas.G@microchip.com.com>]

From: peter chang <dpf@google.com>

the missing task completions appear to be because the driver shadow
structures for the command issue queue can get out of sync between
issues because the locking is inconsistent (none, host adapter lock,
and per-cpu issue queue). the inconsistency is because sata requests
issue per-cpu but management commands (eg, aborts etc) issue
from queue zero. if a sata request issues from cpu zero when a
management request issues, then there is some 'tearing' and the issue
queue is sort of broken and we lose track of issues.

disabling interrupts may be overkill because there may not be cases
where we're using this from interrupt context (the interrupt path
has a different per-queue lock).

Signed-off-by: peter chang <dpf@google.com>
Signed-off-by: Viswas G <Viswas.G@microchip.com>
Signed-off-by: Ruksar Devadi <Ruksar.devadi@microchip.com>
Signed-off-by: Radha Ramachandran <radha@google.com>
---
 drivers/scsi/pm8001/pm8001_hwi.c | 21 +++++++++++++++------
 drivers/scsi/pm8001/pm80xx_hwi.c |  8 --------
 2 files changed, 15 insertions(+), 14 deletions(-)

diff --git a/drivers/scsi/pm8001/pm8001_hwi.c b/drivers/scsi/pm8001/pm8001_hwi.c
index 2b7b2954ec31..597d7a096a97 100644
--- a/drivers/scsi/pm8001/pm8001_hwi.c
+++ b/drivers/scsi/pm8001/pm8001_hwi.c
@@ -1356,12 +1356,19 @@ int pm8001_mpi_build_cmd(struct pm8001_hba_info *pm8001_ha,
 {
 	u32 Header = 0, hpriority = 0, bc = 1, category = 0x02;
 	void *pMessage;
-
-	if (pm8001_mpi_msg_free_get(circularQ, pm8001_ha->iomb_size,
-		&pMessage) < 0) {
+	unsigned long flags;
+	int q_index = circularQ - pm8001_ha->inbnd_q_tbl;
+	int rv = -1;
+
+	WARN_ON(q_index >= PM8001_MAX_INB_NUM);
+	spin_lock_irqsave(&circularQ->iq_lock, flags);
+	rv = pm8001_mpi_msg_free_get(circularQ, pm8001_ha->iomb_size,
+			&pMessage);
+	if (rv < 0) {
 		PM8001_IO_DBG(pm8001_ha,
-			pm8001_printk("No free mpi buffer\n"));
-		return -ENOMEM;
+			      pm8001_printk("No free mpi buffer\n"));
+		rv = -ENOMEM;
+		goto done;
 	}
 
 	if (nb > (pm8001_ha->iomb_size - sizeof(struct mpi_msg_hdr)))
@@ -1384,7 +1391,9 @@ int pm8001_mpi_build_cmd(struct pm8001_hba_info *pm8001_ha,
 		pm8001_printk("INB Q %x OPCODE:%x , UPDATED PI=%d CI=%d\n",
 			responseQueue, opCode, circularQ->producer_idx,
 			circularQ->consumer_index));
-	return 0;
+done:
+	spin_unlock_irqrestore(&circularQ->iq_lock, flags);
+	return rv;
 }
 
 u32 pm8001_mpi_msg_free_set(struct pm8001_hba_info *pm8001_ha, void *pMsg,
diff --git a/drivers/scsi/pm8001/pm80xx_hwi.c b/drivers/scsi/pm8001/pm80xx_hwi.c
index 7593f248afb2..5fe50e0effcd 100644
--- a/drivers/scsi/pm8001/pm80xx_hwi.c
+++ b/drivers/scsi/pm8001/pm80xx_hwi.c
@@ -4281,7 +4281,6 @@ static int pm80xx_chip_smp_req(struct pm8001_hba_info *pm8001_ha,
 	char *preq_dma_addr = NULL;
 	__le64 tmp_addr;
 	u32 i, length;
-	unsigned long flags;
 
 	memset(&smp_cmd, 0, sizeof(smp_cmd));
 	/*
@@ -4377,10 +4376,8 @@ static int pm80xx_chip_smp_req(struct pm8001_hba_info *pm8001_ha,
 
 	build_smp_cmd(pm8001_dev->device_id, smp_cmd.tag,
 				&smp_cmd, pm8001_ha->smp_exp_mode, length);
-	spin_lock_irqsave(&circularQ->iq_lock, flags);
 	rc = pm8001_mpi_build_cmd(pm8001_ha, circularQ, opc, &smp_cmd,
 			sizeof(smp_cmd), 0);
-	spin_unlock_irqrestore(&circularQ->iq_lock, flags);
 	if (rc)
 		goto err_out_2;
 	return 0;
@@ -4444,7 +4441,6 @@ static int pm80xx_chip_ssp_io_req(struct pm8001_hba_info *pm8001_ha,
 	u64 phys_addr, start_addr, end_addr;
 	u32 end_addr_high, end_addr_low;
 	struct inbound_queue_table *circularQ;
-	unsigned long flags;
 	u32 q_index, cpu_id;
 	u32 opc = OPC_INB_SSPINIIOSTART;
 	memset(&ssp_cmd, 0, sizeof(ssp_cmd));
@@ -4582,10 +4578,8 @@ static int pm80xx_chip_ssp_io_req(struct pm8001_hba_info *pm8001_ha,
 			ssp_cmd.esgl = 0;
 		}
 	}
-	spin_lock_irqsave(&circularQ->iq_lock, flags);
 	ret = pm8001_mpi_build_cmd(pm8001_ha, circularQ, opc,
 			&ssp_cmd, sizeof(ssp_cmd), q_index);
-	spin_unlock_irqrestore(&circularQ->iq_lock, flags);
 	return ret;
 }
 
@@ -4819,10 +4813,8 @@ static int pm80xx_chip_sata_req(struct pm8001_hba_info *pm8001_ha,
 			}
 		}
 	}
-	spin_lock_irqsave(&circularQ->iq_lock, flags);
 	ret = pm8001_mpi_build_cmd(pm8001_ha, circularQ, opc,
 			&sata_cmd, sizeof(sata_cmd), q_index);
-	spin_unlock_irqrestore(&circularQ->iq_lock, flags);
 	return ret;
 }
 
-- 
2.16.3