scsi: lpfc: Rework MIB Rx Monitor debug info logic

The kernel test robot reported the following sparse warning:

arch/arm64/include/asm/cmpxchg.h:88:1: sparse: sparse: cast truncates
   bits from constant value (369 becomes 69)

On arm64, atomic_xchg only works on 8-bit byte fields.  Thus, the macro
usage of LPFC_RXMONITOR_TABLE_IN_USE can be unintentionally truncated
leading to all logic involving the LPFC_RXMONITOR_TABLE_IN_USE macro to not
work properly.

Replace the Rx Table atomic_t indexing logic with a new
lpfc_rx_info_monitor structure that holds a circular ring buffer.  For
locking semantics, a spinlock_t is used.

Link: https://lore.kernel.org/r/20220819011736.14141-4-jsmart2021@gmail.com
Fixes: 17b27ac59224 ("scsi: lpfc: Add rx monitoring statistics")
Cc: <stable@vger.kernel.org> # v5.15+
Co-developed-by: Justin Tee <justin.tee@broadcom.com>
Signed-off-by: Justin Tee <justin.tee@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

1 files changed, 183 insertions, 7 deletions

diff --git a/drivers/scsi/lpfc/lpfc_sli.c b/drivers/scsi/lpfc/lpfc_sli.c
index 608016725db9..55c9eb39ea19 100644
--- a/drivers/scsi/lpfc/lpfc_sli.c
+++ b/drivers/scsi/lpfc/lpfc_sli.c
@@ -7960,6 +7960,172 @@ static void lpfc_sli4_dip(struct lpfc_hba *phba)
 }
 
 /**
+ * lpfc_rx_monitor_create_ring - Initialize ring buffer for rx_monitor
+ * @rx_monitor: Pointer to lpfc_rx_info_monitor object
+ * @entries: Number of rx_info_entry objects to allocate in ring
+ *
+ * Return:
+ * 0 - Success
+ * ENOMEM - Failure to kmalloc
+ **/
+int lpfc_rx_monitor_create_ring(struct lpfc_rx_info_monitor *rx_monitor,
+				u32 entries)
+{
+	rx_monitor->ring = kmalloc_array(entries, sizeof(struct rx_info_entry),
+					 GFP_KERNEL);
+	if (!rx_monitor->ring)
+		return -ENOMEM;
+
+	rx_monitor->head_idx = 0;
+	rx_monitor->tail_idx = 0;
+	spin_lock_init(&rx_monitor->lock);
+	rx_monitor->entries = entries;
+
+	return 0;
+}
+
+/**
+ * lpfc_rx_monitor_destroy_ring - Free ring buffer for rx_monitor
+ * @rx_monitor: Pointer to lpfc_rx_info_monitor object
+ **/
+void lpfc_rx_monitor_destroy_ring(struct lpfc_rx_info_monitor *rx_monitor)
+{
+	spin_lock(&rx_monitor->lock);
+	kfree(rx_monitor->ring);
+	rx_monitor->ring = NULL;
+	rx_monitor->entries = 0;
+	rx_monitor->head_idx = 0;
+	rx_monitor->tail_idx = 0;
+	spin_unlock(&rx_monitor->lock);
+}
+
+/**
+ * lpfc_rx_monitor_record - Insert an entry into rx_monitor's ring
+ * @rx_monitor: Pointer to lpfc_rx_info_monitor object
+ * @entry: Pointer to rx_info_entry
+ *
+ * Used to insert an rx_info_entry into rx_monitor's ring.  Note that this is a
+ * deep copy of rx_info_entry not a shallow copy of the rx_info_entry ptr.
+ *
+ * This is called from lpfc_cmf_timer, which is in timer/softirq context.
+ *
+ * In cases of old data overflow, we do a best effort of FIFO order.
+ **/
+void lpfc_rx_monitor_record(struct lpfc_rx_info_monitor *rx_monitor,
+			    struct rx_info_entry *entry)
+{
+	struct rx_info_entry *ring = rx_monitor->ring;
+	u32 *head_idx = &rx_monitor->head_idx;
+	u32 *tail_idx = &rx_monitor->tail_idx;
+	spinlock_t *ring_lock = &rx_monitor->lock;
+	u32 ring_size = rx_monitor->entries;
+
+	spin_lock(ring_lock);
+	memcpy(&ring[*tail_idx], entry, sizeof(*entry));
+	*tail_idx = (*tail_idx + 1) % ring_size;
+
+	/* Best effort of FIFO saved data */
+	if (*tail_idx == *head_idx)
+		*head_idx = (*head_idx + 1) % ring_size;
+
+	spin_unlock(ring_lock);
+}
+
+/**
+ * lpfc_rx_monitor_report - Read out rx_monitor's ring
+ * @phba: Pointer to lpfc_hba object
+ * @rx_monitor: Pointer to lpfc_rx_info_monitor object
+ * @buf: Pointer to char buffer that will contain rx monitor info data
+ * @buf_len: Length buf including null char
+ * @max_read_entries: Maximum number of entries to read out of ring
+ *
+ * Used to dump/read what's in rx_monitor's ring buffer.
+ *
+ * If buf is NULL || buf_len == 0, then it is implied that we want to log the
+ * information to kmsg instead of filling out buf.
+ *
+ * Return:
+ * Number of entries read out of the ring
+ **/
+u32 lpfc_rx_monitor_report(struct lpfc_hba *phba,
+			   struct lpfc_rx_info_monitor *rx_monitor, char *buf,
+			   u32 buf_len, u32 max_read_entries)
+{
+	struct rx_info_entry *ring = rx_monitor->ring;
+	struct rx_info_entry *entry;
+	u32 *head_idx = &rx_monitor->head_idx;
+	u32 *tail_idx = &rx_monitor->tail_idx;
+	spinlock_t *ring_lock = &rx_monitor->lock;
+	u32 ring_size = rx_monitor->entries;
+	u32 cnt = 0;
+	char tmp[DBG_LOG_STR_SZ] = {0};
+	bool log_to_kmsg = (!buf || !buf_len) ? true : false;
+
+	if (!log_to_kmsg) {
+		/* clear the buffer to be sure */
+		memset(buf, 0, buf_len);
+
+		scnprintf(buf, buf_len, "\t%-16s%-16s%-16s%-16s%-8s%-8s%-8s"
+					"%-8s%-8s%-8s%-16s\n",
+					"MaxBPI", "Tot_Data_CMF",
+					"Tot_Data_Cmd", "Tot_Data_Cmpl",
+					"Lat(us)", "Avg_IO", "Max_IO", "Bsy",
+					"IO_cnt", "Info", "BWutil(ms)");
+	}
+
+	/* Needs to be _bh because record is called from timer interrupt
+	 * context
+	 */
+	spin_lock_bh(ring_lock);
+	while (*head_idx != *tail_idx) {
+		entry = &ring[*head_idx];
+
+		/* Read out this entry's data. */
+		if (!log_to_kmsg) {
+			/* If !log_to_kmsg, then store to buf. */
+			scnprintf(tmp, sizeof(tmp),
+				  "%03d:\t%-16llu%-16llu%-16llu%-16llu%-8llu"
+				  "%-8llu%-8llu%-8u%-8u%-8u%u(%u)\n",
+				  *head_idx, entry->max_bytes_per_interval,
+				  entry->cmf_bytes, entry->total_bytes,
+				  entry->rcv_bytes, entry->avg_io_latency,
+				  entry->avg_io_size, entry->max_read_cnt,
+				  entry->cmf_busy, entry->io_cnt,
+				  entry->cmf_info, entry->timer_utilization,
+				  entry->timer_interval);
+
+			/* Check for buffer overflow */
+			if ((strlen(buf) + strlen(tmp)) >= buf_len)
+				break;
+
+			/* Append entry's data to buffer */
+			strlcat(buf, tmp, buf_len);
+		} else {
+			lpfc_printf_log(phba, KERN_INFO, LOG_CGN_MGMT,
+					"4410 %02u: MBPI %llu Xmit %llu "
+					"Cmpl %llu Lat %llu ASz %llu Info %02u "
+					"BWUtil %u Int %u slot %u\n",
+					cnt, entry->max_bytes_per_interval,
+					entry->total_bytes, entry->rcv_bytes,
+					entry->avg_io_latency,
+					entry->avg_io_size, entry->cmf_info,
+					entry->timer_utilization,
+					entry->timer_interval, *head_idx);
+		}
+
+		*head_idx = (*head_idx + 1) % ring_size;
+
+		/* Don't feed more than max_read_entries */
+		cnt++;
+		if (cnt >= max_read_entries)
+			break;
+	}
+	spin_unlock_bh(ring_lock);
+
+	return cnt;
+}
+
+/**
  * lpfc_cmf_setup - Initialize idle_stat tracking
  * @phba: Pointer to HBA context object.
  *
@@ -8133,19 +8299,29 @@ no_cmf:
 	phba->cmf_interval_rate = LPFC_CMF_INTERVAL;
 
 	/* Allocate RX Monitor Buffer */
-	if (!phba->rxtable) {
-		phba->rxtable = kmalloc_array(LPFC_MAX_RXMONITOR_ENTRY,
-					      sizeof(struct rxtable_entry),
-					      GFP_KERNEL);
-		if (!phba->rxtable) {
+	if (!phba->rx_monitor) {
+		phba->rx_monitor = kzalloc(sizeof(*phba->rx_monitor),
+					   GFP_KERNEL);
+
+		if (!phba->rx_monitor) {
 			lpfc_printf_log(phba, KERN_ERR, LOG_INIT,
 					"2644 Failed to alloc memory "
 					"for RX Monitor Buffer\n");
 			return -ENOMEM;
 		}
+
+		/* Instruct the rx_monitor object to instantiate its ring */
+		if (lpfc_rx_monitor_create_ring(phba->rx_monitor,
+						LPFC_MAX_RXMONITOR_ENTRY)) {
+			kfree(phba->rx_monitor);
+			phba->rx_monitor = NULL;
+			lpfc_printf_log(phba, KERN_ERR, LOG_INIT,
+					"2645 Failed to alloc memory "
+					"for RX Monitor's Ring\n");
+			return -ENOMEM;
+		}
 	}
-	atomic_set(&phba->rxtable_idx_head, 0);
-	atomic_set(&phba->rxtable_idx_tail, 0);
+
 	return 0;
 }