interconnect: Teach lockdep about icc_bw_lock order

robclark · Georgi Djakov · commit 136191703038 · 2023-08-22T01:25:06.000+03:00
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> Link: https://lore.kernel.org/r/20230807171148.210181-8-robdclark@gmail.com Signed-off-by: Georgi Djakov <djakov@kernel.org>
diff --git 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);

Original file line number	Diff line number	Diff line change
`@@ -1041,13 +1041,21 @@ void icc_sync_state(struct device *dev)`
`1041`	`1041`	`}`
`1042`	`1042`	`}`
`1043`	`1043`	`}`
	`1044`	`+ mutex_unlock(&icc_bw_lock);`
`1044`	`1045`	`mutex_unlock(&icc_lock);`
`1045`	`1046`	`}`
`1046`	`1047`	`EXPORT_SYMBOL_GPL(icc_sync_state);`
`1047`	`1048`
`1048`	`1049`	`static int __init icc_init(void)`
`1049`	`1050`	`{`
`1050`		`- struct device_node *root = of_find_node_by_path("/");`
	`1051`	`+ struct device_node *root;`
	`1052`	`+`
	`1053`	`+ /* Teach lockdep about lock ordering wrt. shrinker: */`
	`1054`	`+ fs_reclaim_acquire(GFP_KERNEL);`
	`1055`	`+ might_lock(&icc_bw_lock);`
	`1056`	`+ fs_reclaim_release(GFP_KERNEL);`
	`1057`	`+`
	`1058`	`+ root = of_find_node_by_path("/");`
`1051`	`1059`
`1052`	`1060`	`providers_count = of_count_icc_providers(root);`
`1053`	`1061`	`of_node_put(root);`