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From:   Rob Clark <robdclark@gmail.com>
To:     dri-devel@lists.freedesktop.org
Cc:     linux-arm-msm@vger.kernel.org, freedreno@lists.freedesktop.org,
        Rob Clark <robdclark@chromium.org>,
        Georgi Djakov <djakov@kernel.org>,
        linux-pm@vger.kernel.org (open list:INTERCONNECT API),
        linux-kernel@vger.kernel.org (open list)
Subject: [PATCH v3 7/9] interconnect: Teach lockdep about icc_bw_lock order
Date:   Thu,  3 Aug 2023 15:01:55 -0700
Message-ID: <20230803220202.78036-8-robdclark@gmail.com>
In-Reply-To: <20230803220202.78036-1-robdclark@gmail.com>
References: <20230803220202.78036-1-robdclark@gmail.com>
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From: Rob Clark <robdclark@chromium.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@chromium.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 e15a92a79df1..1afbc4f7c6e7 100644
--- a/drivers/interconnect/core.c
+++ b/drivers/interconnect/core.c
@@ -1041,13 +1041,21 @@ 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);
-- 
2.41.0