linux-kernel - [PATCH] interconnect:Replace mutex with rt_mutex for icc_bw

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Date: Tue, 20 Feb 2024 15:43:00 +0800
From: Rumeng Wang <wangrumeng@...omi.corp-partner.google.com>
To: djakov@...nel.org
Cc: linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	fengqi@...omi.com,
	xuyingfeng@...omi.com,
	wangrumeng <wangrumeng@...omi.corp-partner.google.com>
Subject: [PATCH] interconnect:Replace mutex with rt_mutex for icc_bw_lock

From: wangrumeng <wangrumeng@...omi.corp-partner.google.com>

Replace existing mutex with rt_mutex to prevent priority inversion
between clients, which can cause unacceptable delays in some cases.

Signed-off-by: wangrumeng <wangrumeng@...omi.corp-partner.google.com>
---
 drivers/interconnect/core.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/drivers/interconnect/core.c b/drivers/interconnect/core.c
index 50bac2d79d9b..467d42cc7e49 100644
--- a/drivers/interconnect/core.c
+++ b/drivers/interconnect/core.c
@@ -14,6 +14,7 @@
 #include <linux/interconnect-provider.h>
 #include <linux/list.h>
 #include <linux/mutex.h>
+#include <linux/rtmutex.h>
 #include <linux/slab.h>
 #include <linux/of.h>
 #include <linux/overflow.h>
@@ -28,7 +29,7 @@ static LIST_HEAD(icc_providers);
 static int providers_count;
 static bool synced_state;
 static DEFINE_MUTEX(icc_lock);
-static DEFINE_MUTEX(icc_bw_lock);
+static DEFINE_RT_MUTEX(icc_bw_lock);
 static struct dentry *icc_debugfs_dir;
 
 static void icc_summary_show_one(struct seq_file *s, struct icc_node *n)
@@ -698,7 +699,7 @@ int icc_set_bw(struct icc_path *path, u32 avg_bw, u32 peak_bw)
 	if (WARN_ON(IS_ERR(path) || !path->num_nodes))
 		return -EINVAL;
 
-	mutex_lock(&icc_bw_lock);
+	rt_mutex_lock(&icc_bw_lock);
 
 	old_avg = path->reqs[0].avg_bw;
 	old_peak = path->reqs[0].peak_bw;
@@ -730,7 +731,7 @@ int icc_set_bw(struct icc_path *path, u32 avg_bw, u32 peak_bw)
 		apply_constraints(path);
 	}
 
-	mutex_unlock(&icc_bw_lock);
+	rt_mutex_unlock(&icc_bw_lock);
 
 	trace_icc_set_bw_end(path, ret);
 
@@ -939,7 +940,7 @@ void icc_node_add(struct icc_node *node, struct icc_provider *provider)
 		return;
 
 	mutex_lock(&icc_lock);
-	mutex_lock(&icc_bw_lock);
+	rt_mutex_lock(&icc_bw_lock);
 
 	node->provider = provider;
 	list_add_tail(&node->node_list, &provider->nodes);
@@ -968,7 +969,7 @@ void icc_node_add(struct icc_node *node, struct icc_provider *provider)
 	node->avg_bw = 0;
 	node->peak_bw = 0;
 
-	mutex_unlock(&icc_bw_lock);
+	rt_mutex_unlock(&icc_bw_lock);
 	mutex_unlock(&icc_lock);
 }
 EXPORT_SYMBOL_GPL(icc_node_add);
@@ -1094,7 +1095,7 @@ void icc_sync_state(struct device *dev)
 		return;
 
 	mutex_lock(&icc_lock);
-	mutex_lock(&icc_bw_lock);
+	rt_mutex_lock(&icc_bw_lock);
 	synced_state = true;
 	list_for_each_entry(p, &icc_providers, provider_list) {
 		dev_dbg(p->dev, "interconnect provider is in synced state\n");
@@ -1107,7 +1108,7 @@ void icc_sync_state(struct device *dev)
 			}
 		}
 	}
-	mutex_unlock(&icc_bw_lock);
+	rt_mutex_unlock(&icc_bw_lock);
 	mutex_unlock(&icc_lock);
 }
 EXPORT_SYMBOL_GPL(icc_sync_state);
-- 
2.43.2