[PATCH v3 0/3] Fix i2c mux module refcount issues

[PATCH v3 0/3] Fix i2c mux module refcount issues

[Herve Codina]

Hi,

Some i2c mux drivers wrongly use the pair of_find_i2c_adapter_by_node()
/ i2c_put_adapter() to lock the parent adapter.

Indeed, i2c_put_adapter() decrements the module refcount while
of_find_i2c_adapter_by_node() does not increment it. This leads to an
overflow over zero of the parent adapter user counter.

Identified mux drivers impacted are:
- i2c-mux-gpmux
- i2c-demux-pinctrl
- i2c-mux-pinctrl

Commit 48e9743dd648 ("i2c: core: add and export of_get_i2c_adapter_by_node()
interface") introduces of_get_i2c_adapter_by_node() to correctly handle
this refcount issue.

This series fixes the 3 identified mux drivers replacing the
of_find_i2c_adapter_by_node() call by an of_get_i2c_adapter_by_node()
call.

Compare to the previous iteration
  https://lore.kernel.org/linux-kernel/20231019101017.425284-1-herve.codina@bootlin.com/
This v3 series:
 - Fixes a wrong <tab> char in a commit log message
 - Add 'Cc: stable@vger.kernel.org'
 - Add Reviewed-by tags

Best regards,
Hervé

Changes v2 -> v3
  - Patch 2
    Replace a wrong <tab> char by a <space> char in commit message

  - All patches
    Add 'Cc: stable@vger.kernel.org'
    Add 'Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>'

Changes v1 -> v2:
  - All patches
    Fix commit log
    Add relevant Fixes tag
    Add 'Acked-by: Peter Rosin <peda@axentia.se>'

Herve Codina (3):
  i2c: muxes: i2c-mux-pinctrl: Use of_get_i2c_adapter_by_node()
  i2c: muxes: i2c-demux-pinctrl: Use of_get_i2c_adapter_by_node()
  i2c: muxes: i2c-mux-gpmux: Use of_get_i2c_adapter_by_node()

 drivers/i2c/muxes/i2c-demux-pinctrl.c | 2 +-
 drivers/i2c/muxes/i2c-mux-gpmux.c     | 2 +-
 drivers/i2c/muxes/i2c-mux-pinctrl.c   | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

-- 
2.41.0

[PATCH v3 1/3] i2c: muxes: i2c-mux-pinctrl: Use of_get_i2c_adapter_by_node()

[Herve Codina]

i2c-mux-pinctrl uses the pair of_find_i2c_adapter_by_node() /
i2c_put_adapter(). These pair alone is not correct to properly lock the
I2C parent adapter.

Indeed, i2c_put_adapter() decrements the module refcount while
of_find_i2c_adapter_by_node() does not increment it. This leads to an
underflow of the parent module refcount.

Use the dedicated function, of_get_i2c_adapter_by_node(), to handle
correctly the module refcount.

Fixes: c4aee3e1b0de ("i2c: mux: pinctrl: remove platform_data")
Signed-off-by: Herve Codina <herve.codina@bootlin.com>
Cc: stable@vger.kernel.org
Acked-by: Peter Rosin <peda@axentia.se>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
---
 drivers/i2c/muxes/i2c-mux-pinctrl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/i2c/muxes/i2c-mux-pinctrl.c b/drivers/i2c/muxes/i2c-mux-pinctrl.c
index 18236b9fa14a..6ebca7bfd8a2 100644
--- a/drivers/i2c/muxes/i2c-mux-pinctrl.c
+++ b/drivers/i2c/muxes/i2c-mux-pinctrl.c
@@ -62,7 +62,7 @@ static struct i2c_adapter *i2c_mux_pinctrl_parent_adapter(struct device *dev)
 		dev_err(dev, "Cannot parse i2c-parent\n");
 		return ERR_PTR(-ENODEV);
 	}
-	parent = of_find_i2c_adapter_by_node(parent_np);
+	parent = of_get_i2c_adapter_by_node(parent_np);
 	of_node_put(parent_np);
 	if (!parent)
 		return ERR_PTR(-EPROBE_DEFER);
-- 
2.41.0

Re: [PATCH v3 1/3] i2c: muxes: i2c-mux-pinctrl: Use of_get_i2c_adapter_by_node()

[Wolfram Sang]

[-- Attachment #1: Type: text/plain, Size: 824 bytes --]

On Fri, Oct 20, 2023 at 05:30:11PM +0200, Herve Codina wrote:
> i2c-mux-pinctrl uses the pair of_find_i2c_adapter_by_node() /
> i2c_put_adapter(). These pair alone is not correct to properly lock the
> I2C parent adapter.
> 
> Indeed, i2c_put_adapter() decrements the module refcount while
> of_find_i2c_adapter_by_node() does not increment it. This leads to an
> underflow of the parent module refcount.
> 
> Use the dedicated function, of_get_i2c_adapter_by_node(), to handle
> correctly the module refcount.
> 
> Fixes: c4aee3e1b0de ("i2c: mux: pinctrl: remove platform_data")
> Signed-off-by: Herve Codina <herve.codina@bootlin.com>
> Cc: stable@vger.kernel.org
> Acked-by: Peter Rosin <peda@axentia.se>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Applied to for-current, thanks!


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[PATCH v3 2/3] i2c: muxes: i2c-demux-pinctrl: Use of_get_i2c_adapter_by_node()

[Herve Codina]

i2c-demux-pinctrl uses the pair of_find_i2c_adapter_by_node() /
i2c_put_adapter(). These pair alone is not correct to properly lock the
I2C parent adapter.

Indeed, i2c_put_adapter() decrements the module refcount while
of_find_i2c_adapter_by_node() does not increment it. This leads to an
underflow of the parent module refcount.

Use the	dedicated function, of_get_i2c_adapter_by_node(), to handle
correctly the module refcount.

Fixes: 50a5ba876908 ("i2c: mux: demux-pinctrl: add driver")
Signed-off-by: Herve Codina <herve.codina@bootlin.com>
Cc: stable@vger.kernel.org
Acked-by: Peter Rosin <peda@axentia.se>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
---
 drivers/i2c/muxes/i2c-demux-pinctrl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/i2c/muxes/i2c-demux-pinctrl.c b/drivers/i2c/muxes/i2c-demux-pinctrl.c
index 22f2280eab7f..9f2e4aa28159 100644
--- a/drivers/i2c/muxes/i2c-demux-pinctrl.c
+++ b/drivers/i2c/muxes/i2c-demux-pinctrl.c
@@ -61,7 +61,7 @@ static int i2c_demux_activate_master(struct i2c_demux_pinctrl_priv *priv, u32 ne
 	if (ret)
 		goto err;
 
-	adap = of_find_i2c_adapter_by_node(priv->chan[new_chan].parent_np);
+	adap = of_get_i2c_adapter_by_node(priv->chan[new_chan].parent_np);
 	if (!adap) {
 		ret = -ENODEV;
 		goto err_with_revert;
-- 
2.41.0

Re: [PATCH v3 2/3] i2c: muxes: i2c-demux-pinctrl: Use of_get_i2c_adapter_by_node()

[Wolfram Sang]

[-- Attachment #1: Type: text/plain, Size: 822 bytes --]

On Fri, Oct 20, 2023 at 05:30:12PM +0200, Herve Codina wrote:
> i2c-demux-pinctrl uses the pair of_find_i2c_adapter_by_node() /
> i2c_put_adapter(). These pair alone is not correct to properly lock the
> I2C parent adapter.
> 
> Indeed, i2c_put_adapter() decrements the module refcount while
> of_find_i2c_adapter_by_node() does not increment it. This leads to an
> underflow of the parent module refcount.
> 
> Use the	dedicated function, of_get_i2c_adapter_by_node(), to handle
> correctly the module refcount.
> 
> Fixes: 50a5ba876908 ("i2c: mux: demux-pinctrl: add driver")
> Signed-off-by: Herve Codina <herve.codina@bootlin.com>
> Cc: stable@vger.kernel.org
> Acked-by: Peter Rosin <peda@axentia.se>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Applied to for-current, thanks!


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[PATCH v3 3/3] i2c: muxes: i2c-mux-gpmux: Use of_get_i2c_adapter_by_node()

[Herve Codina]

i2c-mux-gpmux uses the pair of_find_i2c_adapter_by_node() /
i2c_put_adapter(). These pair alone is not correct to properly lock the
I2C parent adapter.

Indeed, i2c_put_adapter() decrements the module refcount while
of_find_i2c_adapter_by_node() does not increment it. This leads to an
underflow of the parent module refcount.

Use the dedicated function, of_get_i2c_adapter_by_node(), to handle
correctly the module refcount.

Fixes: ac8498f0ce53 ("i2c: i2c-mux-gpmux: new driver")
Signed-off-by: Herve Codina <herve.codina@bootlin.com>
Cc: stable@vger.kernel.org
Acked-by: Peter Rosin <peda@axentia.se>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
---
 drivers/i2c/muxes/i2c-mux-gpmux.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/i2c/muxes/i2c-mux-gpmux.c b/drivers/i2c/muxes/i2c-mux-gpmux.c
index baccf4bfaf02..8305661e1253 100644
--- a/drivers/i2c/muxes/i2c-mux-gpmux.c
+++ b/drivers/i2c/muxes/i2c-mux-gpmux.c
@@ -52,7 +52,7 @@ static struct i2c_adapter *mux_parent_adapter(struct device *dev)
 		dev_err(dev, "Cannot parse i2c-parent\n");
 		return ERR_PTR(-ENODEV);
 	}
-	parent = of_find_i2c_adapter_by_node(parent_np);
+	parent = of_get_i2c_adapter_by_node(parent_np);
 	of_node_put(parent_np);
 	if (!parent)
 		return ERR_PTR(-EPROBE_DEFER);
-- 
2.41.0

Re: [PATCH v3 3/3] i2c: muxes: i2c-mux-gpmux: Use of_get_i2c_adapter_by_node()

[Wolfram Sang]

[-- Attachment #1: Type: text/plain, Size: 813 bytes --]

On Fri, Oct 20, 2023 at 05:30:13PM +0200, Herve Codina wrote:
> i2c-mux-gpmux uses the pair of_find_i2c_adapter_by_node() /
> i2c_put_adapter(). These pair alone is not correct to properly lock the
> I2C parent adapter.
> 
> Indeed, i2c_put_adapter() decrements the module refcount while
> of_find_i2c_adapter_by_node() does not increment it. This leads to an
> underflow of the parent module refcount.
> 
> Use the dedicated function, of_get_i2c_adapter_by_node(), to handle
> correctly the module refcount.
> 
> Fixes: ac8498f0ce53 ("i2c: i2c-mux-gpmux: new driver")
> Signed-off-by: Herve Codina <herve.codina@bootlin.com>
> Cc: stable@vger.kernel.org
> Acked-by: Peter Rosin <peda@axentia.se>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Applied to for-current, thanks!


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