[PATCH v4 7/9] interconnect: Teach lockdep about icc_bw_lock order

From: Rob Clark
Date: Mon Aug 07 2023 - 13:13:08 EST


From: Rob Clark <robdclark@xxxxxxxxxxxx>

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

Signed-off-by: Rob Clark <robdclark@xxxxxxxxxxxx>
---
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