linux-kernel - [PATCH 5.8 138/177] misc: eeprom: at24: register nvmem only after eeprom is ready to use

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Date:   Tue, 15 Sep 2020 16:13:29 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Vadym Kochan <vadym.kochan@...ision.eu>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>
Subject: [PATCH 5.8 138/177] misc: eeprom: at24: register nvmem only after eeprom is ready to use

From: Vadym Kochan <vadym.kochan@...ision.eu>

commit 45df80d7605c25055a85fbc5a8446c81c6c0ca24 upstream.

During nvmem_register() the nvmem core sends notifications when:

    - cell added
    - nvmem added

and during these notifications some callback func may access the nvmem
device, which will fail in case of at24 eeprom because regulator and pm
are enabled after nvmem_register().

Fixes: cd5676db0574 ("misc: eeprom: at24: support pm_runtime control")
Fixes: b20eb4c1f026 ("eeprom: at24: drop unnecessary label")
Cc: stable@...r.kernel.org
Signed-off-by: Vadym Kochan <vadym.kochan@...ision.eu>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@...libre.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/misc/eeprom/at24.c |   11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

--- a/drivers/misc/eeprom/at24.c
+++ b/drivers/misc/eeprom/at24.c
@@ -692,10 +692,6 @@ static int at24_probe(struct i2c_client
 	nvmem_config.word_size = 1;
 	nvmem_config.size = byte_len;
 
-	at24->nvmem = devm_nvmem_register(dev, &nvmem_config);
-	if (IS_ERR(at24->nvmem))
-		return PTR_ERR(at24->nvmem);
-
 	i2c_set_clientdata(client, at24);
 
 	err = regulator_enable(at24->vcc_reg);
@@ -708,6 +704,13 @@ static int at24_probe(struct i2c_client
 	pm_runtime_set_active(dev);
 	pm_runtime_enable(dev);
 
+	at24->nvmem = devm_nvmem_register(dev, &nvmem_config);
+	if (IS_ERR(at24->nvmem)) {
+		pm_runtime_disable(dev);
+		regulator_disable(at24->vcc_reg);
+		return PTR_ERR(at24->nvmem);
+	}
+
 	/*
 	 * Perform a one-byte test read to verify that the
 	 * chip is functional.