linux-kernel - [PATCH] cxl/mbox: Fix debug message print

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Message-Id: <20230731-cxl-fix-clear-event-debug-print-v1-1-42c068f500d1@intel.com>
Date:   Mon, 31 Jul 2023 13:52:27 -0700
From:   Ira Weiny <ira.weiny@...el.com>
To:     Davidlohr Bueso <dave@...olabs.net>,
        Jonathan Cameron <jonathan.cameron@...wei.com>,
        Dave Jiang <dave.jiang@...el.com>,
        Alison Schofield <alison.schofield@...el.com>,
        Vishal Verma <vishal.l.verma@...el.com>,
        Dan Williams <dan.j.williams@...el.com>
Cc:     Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        linux-cxl@...r.kernel.org, linux-kernel@...r.kernel.org,
        Ira Weiny <ira.weiny@...el.com>
Subject: [PATCH] cxl/mbox: Fix debug message print

The handle value used to report an event being cleared by dev_dbg() is
incorrect due to a post increment of the payload handle index.

Delay the increment of the index until after the print.  Also add the
debugging for event processing which was useful in finding this bug.

To: Davidlohr Bueso <dave@...olabs.net>
To: Jonathan Cameron <jonathan.cameron@...wei.com>
To: Dave Jiang <dave.jiang@...el.com>
To: Alison Schofield <alison.schofield@...el.com>
To: Vishal Verma <vishal.l.verma@...el.com>
To: Dan Williams <dan.j.williams@...el.com>
Cc: Jonathan Cameron <Jonathan.Cameron@...wei.com>
Cc: linux-cxl@...r.kernel.org
Cc: linux-kernel@...r.kernel.org
Signed-off-by: Ira Weiny <ira.weiny@...el.com>
---
NOTE: This does fix a bug in the patch referenced below.  However, I
don't think that warrants back porting because this is only a debug
print.

Fixes: 6ebe28f9ec72 ("cxl/mem: Read, trace, and clear events on driver load")
---
 drivers/cxl/core/mbox.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c
index d6d067fbee97..f052d5f174ee 100644
--- a/drivers/cxl/core/mbox.c
+++ b/drivers/cxl/core/mbox.c
@@ -882,9 +882,10 @@ static int cxl_clear_event_record(struct cxl_memdev_state *mds,
 	 */
 	i = 0;
 	for (cnt = 0; cnt < total; cnt++) {
-		payload->handles[i++] = get_pl->records[cnt].hdr.handle;
+		payload->handles[i] = get_pl->records[cnt].hdr.handle;
 		dev_dbg(mds->cxlds.dev, "Event log '%d': Clearing %u\n", log,
 			le16_to_cpu(payload->handles[i]));
+		i++;
 
 		if (i == max_handles) {
 			payload->nr_recs = i;
@@ -946,9 +947,13 @@ static void cxl_mem_get_records_log(struct cxl_memdev_state *mds,
 		if (!nr_rec)
 			break;
 
-		for (i = 0; i < nr_rec; i++)
+		for (i = 0; i < nr_rec; i++) {
+			dev_dbg(dev, "Event log %d: processing handle %u\n",
+				type,
+				le16_to_cpu(payload->records[i].hdr.handle));
 			cxl_event_trace_record(cxlmd, type,
 					       &payload->records[i]);
+		}
 
 		if (payload->flags & CXL_GET_EVENT_FLAG_OVERFLOW)
 			trace_cxl_overflow(cxlmd, type, payload);

---
base-commit: 5d0c230f1de8c7515b6567d9afba1f196fb4e2f4
change-id: 20230731-cxl-fix-clear-event-debug-print-3b57da0e956c

Best regards,
-- 
Ira Weiny <ira.weiny@...el.com>