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Date:   Wed, 2 Mar 2022 12:22:35 +0100
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To:     "linux-i2c@vger.kernel.org" <linux-i2c@vger.kernel.org>
Cc:     Wolfram Sang <wsa+renesas@sang-engineering.com>,
        Christophe JAILLET <christophe.jaillet@wanadoo.fr>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
From:   Peter Rosin <peda@axentia.se>
Subject: [PATCH] i2c: mux: demux-pinctrl: do not deactivate a master that is
 not active
Organization: Axentia Technologies AB
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Attempting to rollback the activation of the current master when
the current master has not been activated is bad. priv->cur_chan
and priv->cur_adap are both still zeroed out and the rollback
may result in attempts to revert an of changeset that has not been
applied and do result in calls to both del and put the zeroed out
i2c_adapter. Maybe it crashes, or whatever, but it's bad in any
case.

Fixes: e9d1a0a41d44 ("i2c: mux: demux-pinctrl: Fix an error handling path in 'i2c_demux_pinctrl_probe()'")
Cc: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Peter Rosin <peda@axentia.se>
---
 drivers/i2c/muxes/i2c-demux-pinctrl.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

Hi!

Either that, or I'm missing something. I found this issue when
reading code, and have made no tests to verify if my analysis
is correct.

Cheers,
Peter

diff --git a/drivers/i2c/muxes/i2c-demux-pinctrl.c b/drivers/i2c/muxes/i2c-demux-pinctrl.c
index 5365199a31f4..f7a7405d4350 100644
--- a/drivers/i2c/muxes/i2c-demux-pinctrl.c
+++ b/drivers/i2c/muxes/i2c-demux-pinctrl.c
@@ -261,7 +261,7 @@ static int i2c_demux_pinctrl_probe(struct platform_device *pdev)
 
 	err = device_create_file(&pdev->dev, &dev_attr_available_masters);
 	if (err)
-		goto err_rollback;
+		goto err_rollback_activation;
 
 	err = device_create_file(&pdev->dev, &dev_attr_current_master);
 	if (err)
@@ -271,8 +271,9 @@ static int i2c_demux_pinctrl_probe(struct platform_device *pdev)
 
 err_rollback_available:
 	device_remove_file(&pdev->dev, &dev_attr_available_masters);
-err_rollback:
+err_rollback_activation:
 	i2c_demux_deactivate_master(priv);
+err_rollback:
 	for (j = 0; j < i; j++) {
 		of_node_put(priv->chan[j].parent_np);
 		of_changeset_destroy(&priv->chan[j].chgset);
-- 
2.20.1