linux-kernel - [PATCH 5/5] perf/x86/uncore: Don't WARN_ON

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Date:   Tue, 29 Nov 2022 11:10:23 -0800
From:   kan.liang@...ux.intel.com
To:     peterz@...radead.org, mingo@...hat.com,
        linux-kernel@...r.kernel.org
Cc:     steve.wahl@....com, alexander.antonov@...ux.intel.com,
        ak@...ux.intel.com, eranian@...gle.com, namhyung@...nel.org,
        Kan Liang <kan.liang@...ux.intel.com>
Subject: [PATCH 5/5] perf/x86/uncore: Don't WARN_ON_ONCE() for a broken discovery table

From: Kan Liang <kan.liang@...ux.intel.com>

The kernel warning message is triggered, when SPR MCC is used.

[   17.945331] ------------[ cut here ]------------
[   17.946305] WARNING: CPU: 65 PID: 1 at
arch/x86/events/intel/uncore_discovery.c:184
intel_uncore_has_discovery_tables+0x4c0/0x65c
[   17.946305] Modules linked in:
[   17.946305] CPU: 65 PID: 1 Comm: swapper/0 Not tainted
5.4.17-2136.313.1-X10-2c+ #4

It's caused by the broken discovery table of UPI.

The discovery tables are from hardware. Except for dropping the broken
information, there is nothing Linux can do. Using WARN_ON_ONCE() is
overkilled.

Use the pr_info() to replace WARN_ON_ONCE(), and specify what uncore unit
is dropped and the reason.

Signed-off-by: Kan Liang <kan.liang@...ux.intel.com>
---
 arch/x86/events/intel/uncore_discovery.c | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/arch/x86/events/intel/uncore_discovery.c b/arch/x86/events/intel/uncore_discovery.c
index abb51191f5af..cb488e41807c 100644
--- a/arch/x86/events/intel/uncore_discovery.c
+++ b/arch/x86/events/intel/uncore_discovery.c
@@ -128,13 +128,21 @@ uncore_insert_box_info(struct uncore_unit_discovery *unit,
 	unsigned int *box_offset, *ids;
 	int i;
 
-	if (WARN_ON_ONCE(!unit->ctl || !unit->ctl_offset || !unit->ctr_offset))
+	if (!unit->ctl || !unit->ctl_offset || !unit->ctr_offset) {
+		pr_info("Invalid address is detected for uncore type %d box %d, "
+			"Disable the uncore unit.\n",
+			unit->box_type, unit->box_id);
 		return;
+	}
 
 	if (parsed) {
 		type = search_uncore_discovery_type(unit->box_type);
-		if (WARN_ON_ONCE(!type))
+		if (!type) {
+			pr_info("A spurious uncore type %d is detected, "
+				"Disable the uncore type.\n",
+				unit->box_type);
 			return;
+		}
 		/* Store the first box of each die */
 		if (!type->box_ctrl_die[die])
 			type->box_ctrl_die[die] = unit->ctl;
@@ -169,8 +177,12 @@ uncore_insert_box_info(struct uncore_unit_discovery *unit,
 		ids[i] = type->ids[i];
 		box_offset[i] = type->box_offset[i];
 
-		if (WARN_ON_ONCE(unit->box_id == ids[i]))
+		if (unit->box_id == ids[i]) {
+			pr_info("Duplicate uncore type %d box ID %d is detected, "
+				"Drop the duplicate uncore unit.\n",
+				unit->box_type, unit->box_id);
 			goto free_ids;
+		}
 	}
 	ids[i] = unit->box_id;
 	box_offset[i] = unit->ctl - type->box_ctrl;
-- 
2.35.1