linux-kernel - [PATCH] nvmem: core: WARN_ONCE on nvmem reg_read/write() returning positive values

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Message-ID: <20240725112126.415071-1-joychakr@google.com>
Date: Thu, 25 Jul 2024 11:21:26 +0000
From: Joy Chakraborty <joychakr@...gle.com>
To: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>, 
	Dan Carpenter <dan.carpenter@...aro.org>
Cc: linux-kernel@...r.kernel.org, Joy Chakraborty <joychakr@...gle.com>
Subject: [PATCH] nvmem: core: WARN_ONCE on nvmem reg_read/write() returning
 positive values

Nvmem core currently expects 0 to be returned on successful read/write
and negative for failure from nvmem producers.
Warn incase any nvmem producer returns positive values which might
happen if any producer ends up returning the number of bytes read or
written.

Signed-off-by: Joy Chakraborty <joychakr@...gle.com>
---
 drivers/nvmem/core.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index e1ec3b7200d7..0a42e6a0e8bb 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -58,10 +58,13 @@ static BLOCKING_NOTIFIER_HEAD(nvmem_notifier);
 static int __nvmem_reg_read(struct nvmem_device *nvmem, unsigned int offset,
 			    void *val, size_t bytes)
 {
+	int ret = -EINVAL;
+
 	if (nvmem->reg_read)
-		return nvmem->reg_read(nvmem->priv, offset, val, bytes);
+		ret = nvmem->reg_read(nvmem->priv, offset, val, bytes);
 
-	return -EINVAL;
+	WARN_ONCE(ret > 0, "nvmem reg_read should not return positive value, please return 0 on success");
+	return ret;
 }
 
 static int __nvmem_reg_write(struct nvmem_device *nvmem, unsigned int offset,
@@ -73,6 +76,7 @@ static int __nvmem_reg_write(struct nvmem_device *nvmem, unsigned int offset,
 		gpiod_set_value_cansleep(nvmem->wp_gpio, 0);
 		ret = nvmem->reg_write(nvmem->priv, offset, val, bytes);
 		gpiod_set_value_cansleep(nvmem->wp_gpio, 1);
+		WARN_ONCE(ret > 0, "nvmem reg_write should not return positive value, please return 0 on success");
 		return ret;
 	}
 
-- 
2.45.2.1089.g2a221341d9-goog