linux-kernel - [PATCH] mfd: macsmc: Initialize mutex

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Message-Id: <20250925-macsmc-mutex_init-v1-1-416e9e644735@jannau.net>
Date: Thu, 25 Sep 2025 22:33:18 +0200
From: Janne Grunau <j@...nau.net>
To: Sven Peter <sven@...nel.org>, Neal Gompa <neal@...pa.dev>, 
 Lee Jones <lee@...nel.org>
Cc: asahi@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org, 
 linux-kernel@...r.kernel.org, Janne Grunau <j@...nau.net>
Subject: [PATCH] mfd: macsmc: Initialize mutex

Struct apple_smc's mutex was not initialized before use. Surprisingly
this only resulted in occasional NULL pointer dereferences in
apple_smc_read() calls from the probe() functions of sub devices.

Fixes: e038d985c9823 ("mfd: Add Apple Silicon System Management Controller")
Signed-off-by: Janne Grunau <j@...nau.net>
---
 drivers/mfd/macsmc.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/mfd/macsmc.c b/drivers/mfd/macsmc.c
index 870c8b2028a8fc0e905c8934c2636824cbe5d527..3a117cf19145e86b642f40dc165b542b8df69070 100644
--- a/drivers/mfd/macsmc.c
+++ b/drivers/mfd/macsmc.c
@@ -413,6 +413,7 @@ static int apple_smc_probe(struct platform_device *pdev)
 	if (!smc)
 		return -ENOMEM;
 
+	mutex_init(&smc->mutex);
 	smc->dev = &pdev->dev;
 	smc->sram_base = devm_platform_get_and_ioremap_resource(pdev, 1, &smc->sram);
 	if (IS_ERR(smc->sram_base))

---
base-commit: 8f5ae30d69d7543eee0d70083daf4de8fe15d585
change-id: 20250925-macsmc-mutex_init-80d7cb2aacfa

Best regards,
-- 
Janne Grunau <j@...nau.net>