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authorMatthew R. Ochs <mrochs@linux.vnet.ibm.com>2017-04-12 14:12:55 -0500
committerMartin K. Petersen <martin.petersen@oracle.com>2017-04-13 22:55:41 -0400
commitf918b4a8e6f8bb59c44045f85d10fd9cc7e5a4c0 (patch)
tree99806162d9c6685b626b4c14f34388f98b2f5343 /drivers/scsi/cxlflash
parent76a6ebbeef26b004c36a0c8ee0496bae5428fc31 (diff)
scsi: cxlflash: Serialize RRQ access and support offlevel processing
As further staging to support processing the HRRQ by other means, access to the HRRQ needs to be serialized by a disabled lock. This will allow safe access in other non-hardware interrupt contexts. In an effort to minimize the period where interrupts are disabled, support is added to queue up commands harvested from the RRQ such that they can be processed with hardware interrupts enabled. While this doesn't offer any improvement with processing on a hardware interrupt it will help when IRQ polling is supported and the command completions can execute on softirq context. Signed-off-by: Matthew R. Ochs <mrochs@linux.vnet.ibm.com> Signed-off-by: Uma Krishnan <ukrishn@linux.vnet.ibm.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Diffstat (limited to 'drivers/scsi/cxlflash')
-rw-r--r--drivers/scsi/cxlflash/common.h2
-rw-r--r--drivers/scsi/cxlflash/main.c42
2 files changed, 37 insertions, 7 deletions
diff --git a/drivers/scsi/cxlflash/common.h b/drivers/scsi/cxlflash/common.h
index d11dcc59ff46..9d56b8c797c4 100644
--- a/drivers/scsi/cxlflash/common.h
+++ b/drivers/scsi/cxlflash/common.h
@@ -134,6 +134,7 @@ struct afu_cmd {
struct afu *parent;
struct scsi_cmnd *scp;
struct completion cevent;
+ struct list_head queue;
u8 cmd_tmf:1;
@@ -181,6 +182,7 @@ struct afu {
struct sisl_ioarcb *hsq_start;
struct sisl_ioarcb *hsq_end;
struct sisl_ioarcb *hsq_curr;
+ spinlock_t hrrq_slock;
u64 *hrrq_start;
u64 *hrrq_end;
u64 *hrrq_curr;
diff --git a/drivers/scsi/cxlflash/main.c b/drivers/scsi/cxlflash/main.c
index 30c09593c122..8c207ba8474b 100644
--- a/drivers/scsi/cxlflash/main.c
+++ b/drivers/scsi/cxlflash/main.c
@@ -1157,10 +1157,13 @@ cxlflash_sync_err_irq_exit:
/**
* process_hrrq() - process the read-response queue
* @afu: AFU associated with the host.
+ * @doneq: Queue of commands harvested from the RRQ.
+ *
+ * This routine must be called holding the disabled RRQ spin lock.
*
* Return: The number of entries processed.
*/
-static int process_hrrq(struct afu *afu)
+static int process_hrrq(struct afu *afu, struct list_head *doneq)
{
struct afu_cmd *cmd;
struct sisl_ioasa *ioasa;
@@ -1189,7 +1192,7 @@ static int process_hrrq(struct afu *afu)
cmd = container_of(ioarcb, struct afu_cmd, rcb);
}
- cmd_complete(cmd);
+ list_add_tail(&cmd->queue, doneq);
/* Advance to next entry or wrap and flip the toggle bit */
if (hrrq_curr < hrrq_end)
@@ -1210,17 +1213,43 @@ static int process_hrrq(struct afu *afu)
}
/**
+ * process_cmd_doneq() - process a queue of harvested RRQ commands
+ * @doneq: Queue of completed commands.
+ *
+ * Note that upon return the queue can no longer be trusted.
+ */
+static void process_cmd_doneq(struct list_head *doneq)
+{
+ struct afu_cmd *cmd, *tmp;
+
+ WARN_ON(list_empty(doneq));
+
+ list_for_each_entry_safe(cmd, tmp, doneq, queue)
+ cmd_complete(cmd);
+}
+
+/**
* cxlflash_rrq_irq() - interrupt handler for read-response queue (normal path)
* @irq: Interrupt number.
* @data: Private data provided at interrupt registration, the AFU.
*
- * Return: Always return IRQ_HANDLED.
+ * Return: IRQ_HANDLED or IRQ_NONE when no ready entries found.
*/
static irqreturn_t cxlflash_rrq_irq(int irq, void *data)
{
struct afu *afu = (struct afu *)data;
+ unsigned long hrrq_flags;
+ LIST_HEAD(doneq);
+ int num_entries = 0;
- process_hrrq(afu);
+ spin_lock_irqsave(&afu->hrrq_slock, hrrq_flags);
+ num_entries = process_hrrq(afu, &doneq);
+ spin_unlock_irqrestore(&afu->hrrq_slock, hrrq_flags);
+
+ if (num_entries == 0)
+ return IRQ_NONE;
+
+ process_cmd_doneq(&doneq);
return IRQ_HANDLED;
}
@@ -1540,14 +1569,13 @@ static int start_afu(struct cxlflash_cfg *cfg)
init_pcr(cfg);
- /* After an AFU reset, RRQ entries are stale, clear them */
+ /* Initialize RRQ */
memset(&afu->rrq_entry, 0, sizeof(afu->rrq_entry));
-
- /* Initialize RRQ pointers */
afu->hrrq_start = &afu->rrq_entry[0];
afu->hrrq_end = &afu->rrq_entry[NUM_RRQ_ENTRY - 1];
afu->hrrq_curr = afu->hrrq_start;
afu->toggle = 1;
+ spin_lock_init(&afu->hrrq_slock);
/* Initialize SQ */
if (afu_is_sq_cmd_mode(afu)) {