Patch "soc: qcom: pmic_glink: Make client-lock non-sleeping" has been added to the 6.6-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    soc: qcom: pmic_glink: Make client-lock non-sleeping

to the 6.6-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     soc-qcom-pmic_glink-make-client-lock-non-sleeping.patch
and it can be found in the queue-6.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit be024dabdafc39bf335bff9cff1eea1f6ced2aca
Author: Bjorn Andersson <quic_bjorande@xxxxxxxxxxx>
Date:   Tue Apr 30 20:38:57 2024 -0700

    soc: qcom: pmic_glink: Make client-lock non-sleeping
    
    [ Upstream commit 9329933699b32d467a99befa20415c4b2172389a ]
    
    The recently introduced commit '635ce0db8956 ("soc: qcom: pmic_glink:
    don't traverse clients list without a lock")' ensured that the clients
    list is not modified while traversed.
    
    But the callback is made from the GLINK IRQ handler and as such this
    mutual exclusion can not be provided by a (sleepable) mutex.
    
    Replace the mutex with a spinlock.
    
    Fixes: 635ce0db8956 ("soc: qcom: pmic_glink: don't traverse clients list without a lock")
    Signed-off-by: Bjorn Andersson <quic_bjorande@xxxxxxxxxxx>
    Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
    Link: https://lore.kernel.org/r/20240430-pmic-glink-sleep-while-atomic-v1-1-88fb493e8545@xxxxxxxxxxx
    Signed-off-by: Bjorn Andersson <andersson@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/soc/qcom/pmic_glink.c b/drivers/soc/qcom/pmic_glink.c
index 062ff7b12de6a..61a359938b6c4 100644
--- a/drivers/soc/qcom/pmic_glink.c
+++ b/drivers/soc/qcom/pmic_glink.c
@@ -11,6 +11,7 @@
 #include <linux/slab.h>
 #include <linux/soc/qcom/pdr.h>
 #include <linux/soc/qcom/pmic_glink.h>
+#include <linux/spinlock.h>
 
 enum {
 	PMIC_GLINK_CLIENT_BATT = 0,
@@ -39,7 +40,7 @@ struct pmic_glink {
 	unsigned int pdr_state;
 
 	/* serializing clients list updates */
-	struct mutex client_lock;
+	spinlock_t client_lock;
 	struct list_head clients;
 };
 
@@ -61,10 +62,11 @@ static void _devm_pmic_glink_release_client(struct device *dev, void *res)
 {
 	struct pmic_glink_client *client = (struct pmic_glink_client *)res;
 	struct pmic_glink *pg = client->pg;
+	unsigned long flags;
 
-	mutex_lock(&pg->client_lock);
+	spin_lock_irqsave(&pg->client_lock, flags);
 	list_del(&client->node);
-	mutex_unlock(&pg->client_lock);
+	spin_unlock_irqrestore(&pg->client_lock, flags);
 }
 
 struct pmic_glink_client *devm_pmic_glink_register_client(struct device *dev,
@@ -75,6 +77,7 @@ struct pmic_glink_client *devm_pmic_glink_register_client(struct device *dev,
 {
 	struct pmic_glink_client *client;
 	struct pmic_glink *pg = dev_get_drvdata(dev->parent);
+	unsigned long flags;
 
 	client = devres_alloc(_devm_pmic_glink_release_client, sizeof(*client), GFP_KERNEL);
 	if (!client)
@@ -87,12 +90,12 @@ struct pmic_glink_client *devm_pmic_glink_register_client(struct device *dev,
 	client->priv = priv;
 
 	mutex_lock(&pg->state_lock);
-	mutex_lock(&pg->client_lock);
+	spin_lock_irqsave(&pg->client_lock, flags);
 
 	list_add(&client->node, &pg->clients);
 	client->pdr_notify(client->priv, pg->client_state);
 
-	mutex_unlock(&pg->client_lock);
+	spin_unlock_irqrestore(&pg->client_lock, flags);
 	mutex_unlock(&pg->state_lock);
 
 	devres_add(dev, client);
@@ -115,6 +118,7 @@ static int pmic_glink_rpmsg_callback(struct rpmsg_device *rpdev, void *data,
 	struct pmic_glink_client *client;
 	struct pmic_glink_hdr *hdr;
 	struct pmic_glink *pg = dev_get_drvdata(&rpdev->dev);
+	unsigned long flags;
 
 	if (len < sizeof(*hdr)) {
 		dev_warn(pg->dev, "ignoring truncated message\n");
@@ -123,12 +127,12 @@ static int pmic_glink_rpmsg_callback(struct rpmsg_device *rpdev, void *data,
 
 	hdr = data;
 
-	mutex_lock(&pg->client_lock);
+	spin_lock_irqsave(&pg->client_lock, flags);
 	list_for_each_entry(client, &pg->clients, node) {
 		if (client->id == le32_to_cpu(hdr->owner))
 			client->cb(data, len, client->priv);
 	}
-	mutex_unlock(&pg->client_lock);
+	spin_unlock_irqrestore(&pg->client_lock, flags);
 
 	return 0;
 }
@@ -168,6 +172,7 @@ static void pmic_glink_state_notify_clients(struct pmic_glink *pg)
 {
 	struct pmic_glink_client *client;
 	unsigned int new_state = pg->client_state;
+	unsigned long flags;
 
 	if (pg->client_state != SERVREG_SERVICE_STATE_UP) {
 		if (pg->pdr_state == SERVREG_SERVICE_STATE_UP && pg->ept)
@@ -178,10 +183,10 @@ static void pmic_glink_state_notify_clients(struct pmic_glink *pg)
 	}
 
 	if (new_state != pg->client_state) {
-		mutex_lock(&pg->client_lock);
+		spin_lock_irqsave(&pg->client_lock, flags);
 		list_for_each_entry(client, &pg->clients, node)
 			client->pdr_notify(client->priv, new_state);
-		mutex_unlock(&pg->client_lock);
+		spin_unlock_irqrestore(&pg->client_lock, flags);
 		pg->client_state = new_state;
 	}
 }
@@ -268,7 +273,7 @@ static int pmic_glink_probe(struct platform_device *pdev)
 	pg->dev = &pdev->dev;
 
 	INIT_LIST_HEAD(&pg->clients);
-	mutex_init(&pg->client_lock);
+	spin_lock_init(&pg->client_lock);
 	mutex_init(&pg->state_lock);
 
 	match_data = (unsigned long *)of_device_get_match_data(&pdev->dev);