linux-kernel - [PATCH 13/13] interconnect: Teach lockdep about icc_bw

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Message-Id: <20230312204150.1353517-14-robdclark@gmail.com>
Date:   Sun, 12 Mar 2023 13:41:41 -0700
From:   Rob Clark <robdclark@...il.com>
To:     dri-devel@...ts.freedesktop.org
Cc:     linux-arm-msm@...r.kernel.org, Rob Clark <robdclark@...omium.org>,
        Georgi Djakov <djakov@...nel.org>,
        linux-pm@...r.kernel.org (open list:INTERCONNECT API),
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH 13/13] interconnect: Teach lockdep about icc_bw_lock order

From: Rob Clark <robdclark@...omium.org>

Teach lockdep that icc_bw_lock is needed in code paths that could
deadlock if they trigger reclaim.

Signed-off-by: Rob Clark <robdclark@...omium.org>
---
 drivers/interconnect/core.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/interconnect/core.c b/drivers/interconnect/core.c
index f7251784765f..5619963ee85c 100644
--- a/drivers/interconnect/core.c
+++ b/drivers/interconnect/core.c
@@ -1127,13 +1127,21 @@ void icc_sync_state(struct device *dev)
 			}
 		}
 	}
+	mutex_unlock(&icc_bw_lock);
 	mutex_unlock(&icc_lock);
 }
 EXPORT_SYMBOL_GPL(icc_sync_state);
 
 static int __init icc_init(void)
 {
-	struct device_node *root = of_find_node_by_path("/");
+	struct device_node *root;
+
+	/* Teach lockdep about lock ordering wrt. shrinker: */
+	fs_reclaim_acquire(GFP_KERNEL);
+	might_lock(&icc_bw_lock);
+	fs_reclaim_release(GFP_KERNEL);
+
+	root = of_find_node_by_path("/");
 
 	providers_count = of_count_icc_providers(root);
 	of_node_put(root);
-- 
2.39.2