linux-kernel - [PATCH] pinctrl: core: Make p->state in order in pinctrl_commit

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Message-ID: <20221027065408.36977-1-quic_aiquny@quicinc.com>
Date:   Thu, 27 Oct 2022 14:54:08 +0800
From:   Maria Yu <quic_aiquny@...cinc.com>
To:     <linus.walleij@...aro.org>
CC:     Maria Yu <quic_aiquny@...cinc.com>, <linux-gpio@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH] pinctrl: core: Make p->state in order in pinctrl_commit_state

We've got a dump that current cpu is in pinctrl_commit_state, the
old_state != p->state while the stack is still in the process of
pinmux_disable_setting. So it means even if the current p->state is
changed in new state, the settings are not yet up-to-date enabled
complete yet.

Currently p->state in different value to synchronize the
pinctrl_commit_state behaviors. The p->state will have transaction like
old_state -> NULL -> new_state. When in old_state, it will try to
disable all the all state settings. And when after new state settings
enabled, p->state will changed to the new state after that. So use
smp_mb to synchronize the p->state variable and the settings in order.
---
 drivers/pinctrl/core.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/pinctrl/core.c b/drivers/pinctrl/core.c
index 9e57f4c62e60..cd917a5b1a0a 100644
--- a/drivers/pinctrl/core.c
+++ b/drivers/pinctrl/core.c
@@ -1256,6 +1256,7 @@ static int pinctrl_commit_state(struct pinctrl *p, struct pinctrl_state *state)
 		}
 	}
 
+	smp_mb();
 	p->state = NULL;
 
 	/* Apply all the settings for the new state - pinmux first */
@@ -1305,6 +1306,7 @@ static int pinctrl_commit_state(struct pinctrl *p, struct pinctrl_state *state)
 			pinctrl_link_add(setting->pctldev, p->dev);
 	}
 
+	smp_mb();
 	p->state = state;
 
 	return 0;
-- 
2.17.1