[PATCH platform 0/4] Fixes for issues with coverity, locking, redundant checks

[PATCH platform 0/4] Fixes for issues with coverity, locking, redundant checks

[Vadim Pasternak]

The patch set includes fixes for several issues:
Patch #1: fixes coverity issue.
Patch #2: fixes locking dependency issue.
Patches #3-#4: remove unnecessary code.

Vadim Pasternak (4):
  platform/mellanox: mlxreg-lc: Fix coverity warning
  platform/mellanox: mlxreg-lc: Fix locking issue
  platform/mellanox: Remove unnecessary code
  platform/mellanox: Remove redundant 'NULL' check

 drivers/platform/mellanox/mlxreg-lc.c | 53 ++++++++++++++++-----------
 1 file changed, 31 insertions(+), 22 deletions(-)

-- 
2.20.1

[PATCH platform 1/4] platform/mellanox: mlxreg-lc: Fix coverity warning

[Vadim Pasternak]

Fix smatch warning:
drivers/platform/mellanox/mlxreg-lc.c:866 mlxreg_lc_probe() warn: passing zero to 'PTR_ERR'
by removing 'err = PTR_ERR(regmap)'.

Fixes: b4b830a34d80 ("platform/mellanox: mlxreg-lc: Fix error flow and extend verbosity")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Vadim Pasternak <vadimp@nvidia.com>
---
 drivers/platform/mellanox/mlxreg-lc.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/platform/mellanox/mlxreg-lc.c b/drivers/platform/mellanox/mlxreg-lc.c
index 55834ccb4ac7..9a1bfcd24317 100644
--- a/drivers/platform/mellanox/mlxreg-lc.c
+++ b/drivers/platform/mellanox/mlxreg-lc.c
@@ -863,7 +863,6 @@ static int mlxreg_lc_probe(struct platform_device *pdev)
 	if (err) {
 		dev_err(&pdev->dev, "Failed to sync regmap for client %s at bus %d at addr 0x%02x\n",
 			data->hpdev.brdinfo->type, data->hpdev.nr, data->hpdev.brdinfo->addr);
-		err = PTR_ERR(regmap);
 		goto regcache_sync_fail;
 	}
 
-- 
2.20.1

[PATCH platform 2/4] platform/mellanox: mlxreg-lc: Fix locking issue

[Vadim Pasternak]

Fix locking issues:
- mlxreg_lc_state_update() takes a lock when set or clear
  "MLXREG_LC_POWERED".
- All the devices can be deleted before MLXREG_LC_POWERED flag is cleared.

To fix it:
- Add lock() / unlock() at the beginning / end of
  mlxreg_lc_event_handler() and remove locking from
  mlxreg_lc_power_on_off() and mlxreg_lc_enable_disable()
- Add locked version of mlxreg_lc_state_update() -
  mlxreg_lc_state_update_locked() for using outside
  mlxreg_lc_event_handler().

(2) Remove redundant NULL check for of if 'data->notifier'.

Fixes: 62f9529b8d5c87b ("platform/mellanox: mlxreg-lc: Add initial support for Nvidia line card devices")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Vadim Pasternak <vadimp@nvidia.com>
---
 drivers/platform/mellanox/mlxreg-lc.c | 37 ++++++++++++++++++---------
 1 file changed, 25 insertions(+), 12 deletions(-)

diff --git a/drivers/platform/mellanox/mlxreg-lc.c b/drivers/platform/mellanox/mlxreg-lc.c
index 9a1bfcd24317..e578c7bc060b 100644
--- a/drivers/platform/mellanox/mlxreg-lc.c
+++ b/drivers/platform/mellanox/mlxreg-lc.c
@@ -460,8 +460,6 @@ static int mlxreg_lc_power_on_off(struct mlxreg_lc *mlxreg_lc, u8 action)
 	u32 regval;
 	int err;
 
-	mutex_lock(&mlxreg_lc->lock);
-
 	err = regmap_read(mlxreg_lc->par_regmap, mlxreg_lc->data->reg_pwr, &regval);
 	if (err)
 		goto regmap_read_fail;
@@ -474,7 +472,6 @@ static int mlxreg_lc_power_on_off(struct mlxreg_lc *mlxreg_lc, u8 action)
 	err = regmap_write(mlxreg_lc->par_regmap, mlxreg_lc->data->reg_pwr, regval);
 
 regmap_read_fail:
-	mutex_unlock(&mlxreg_lc->lock);
 	return err;
 }
 
@@ -491,8 +488,6 @@ static int mlxreg_lc_enable_disable(struct mlxreg_lc *mlxreg_lc, bool action)
 	 * line card which is already has been enabled. Disabling does not affect the disabled line
 	 * card.
 	 */
-	mutex_lock(&mlxreg_lc->lock);
-
 	err = regmap_read(mlxreg_lc->par_regmap, mlxreg_lc->data->reg_ena, &regval);
 	if (err)
 		goto regmap_read_fail;
@@ -505,7 +500,6 @@ static int mlxreg_lc_enable_disable(struct mlxreg_lc *mlxreg_lc, bool action)
 	err = regmap_write(mlxreg_lc->par_regmap, mlxreg_lc->data->reg_ena, regval);
 
 regmap_read_fail:
-	mutex_unlock(&mlxreg_lc->lock);
 	return err;
 }
 
@@ -537,6 +531,15 @@ mlxreg_lc_sn4800_c16_config_init(struct mlxreg_lc *mlxreg_lc, void *regmap,
 
 static void
 mlxreg_lc_state_update(struct mlxreg_lc *mlxreg_lc, enum mlxreg_lc_state state, u8 action)
+{
+	if (action)
+		mlxreg_lc->state |= state;
+	else
+		mlxreg_lc->state &= ~state;
+}
+
+static void
+mlxreg_lc_state_update_locked(struct mlxreg_lc *mlxreg_lc, enum mlxreg_lc_state state, u8 action)
 {
 	mutex_lock(&mlxreg_lc->lock);
 
@@ -560,8 +563,11 @@ static int mlxreg_lc_event_handler(void *handle, enum mlxreg_hotplug_kind kind,
 	dev_info(mlxreg_lc->dev, "linecard#%d state %d event kind %d action %d\n",
 		 mlxreg_lc->data->slot, mlxreg_lc->state, kind, action);
 
-	if (!(mlxreg_lc->state & MLXREG_LC_INITIALIZED))
+	mutex_lock(&mlxreg_lc->lock);
+	if (!(mlxreg_lc->state & MLXREG_LC_INITIALIZED)) {
+		mutex_unlock(&mlxreg_lc->lock);
 		return 0;
+	}
 
 	switch (kind) {
 	case MLXREG_HOTPLUG_LC_SYNCED:
@@ -574,7 +580,7 @@ static int mlxreg_lc_event_handler(void *handle, enum mlxreg_hotplug_kind kind,
 		if (!(mlxreg_lc->state & MLXREG_LC_POWERED) && action) {
 			err = mlxreg_lc_power_on_off(mlxreg_lc, 1);
 			if (err)
-				return err;
+				goto mlxreg_lc_power_on_off_fail;
 		}
 		/* In case line card is configured - enable it. */
 		if (mlxreg_lc->state & MLXREG_LC_CONFIGURED && action)
@@ -588,12 +594,13 @@ static int mlxreg_lc_event_handler(void *handle, enum mlxreg_hotplug_kind kind,
 				/* In case line card is configured - enable it. */
 				if (mlxreg_lc->state & MLXREG_LC_CONFIGURED)
 					err = mlxreg_lc_enable_disable(mlxreg_lc, 1);
+				mutex_unlock(&mlxreg_lc->lock);
 				return err;
 			}
 			err = mlxreg_lc_create_static_devices(mlxreg_lc, mlxreg_lc->main_devs,
 							      mlxreg_lc->main_devs_num);
 			if (err)
-				return err;
+				goto mlxreg_lc_create_static_devices_fail;
 
 			/* In case line card is already in ready state - enable it. */
 			if (mlxreg_lc->state & MLXREG_LC_CONFIGURED)
@@ -620,6 +627,10 @@ static int mlxreg_lc_event_handler(void *handle, enum mlxreg_hotplug_kind kind,
 		break;
 	}
 
+mlxreg_lc_power_on_off_fail:
+mlxreg_lc_create_static_devices_fail:
+	mutex_unlock(&mlxreg_lc->lock);
+
 	return err;
 }
 
@@ -665,7 +676,7 @@ static int mlxreg_lc_completion_notify(void *handle, struct i2c_adapter *parent,
 		if (err)
 			goto mlxreg_lc_create_static_devices_failed;
 
-		mlxreg_lc_state_update(mlxreg_lc, MLXREG_LC_POWERED, 1);
+		mlxreg_lc_state_update_locked(mlxreg_lc, MLXREG_LC_POWERED, 1);
 	}
 
 	/* Verify if line card is synchronized. */
@@ -676,7 +687,7 @@ static int mlxreg_lc_completion_notify(void *handle, struct i2c_adapter *parent,
 	/* Power on line card if necessary. */
 	if (regval & mlxreg_lc->data->mask) {
 		mlxreg_lc->state |= MLXREG_LC_SYNCED;
-		mlxreg_lc_state_update(mlxreg_lc, MLXREG_LC_SYNCED, 1);
+		mlxreg_lc_state_update_locked(mlxreg_lc, MLXREG_LC_SYNCED, 1);
 		if (mlxreg_lc->state & ~MLXREG_LC_POWERED) {
 			err = mlxreg_lc_power_on_off(mlxreg_lc, 1);
 			if (err)
@@ -684,7 +695,7 @@ static int mlxreg_lc_completion_notify(void *handle, struct i2c_adapter *parent,
 		}
 	}
 
-	mlxreg_lc_state_update(mlxreg_lc, MLXREG_LC_INITIALIZED, 1);
+	mlxreg_lc_state_update_locked(mlxreg_lc, MLXREG_LC_INITIALIZED, 1);
 
 	return 0;
 
@@ -904,6 +915,8 @@ static int mlxreg_lc_remove(struct platform_device *pdev)
 	struct mlxreg_core_data *data = dev_get_platdata(&pdev->dev);
 	struct mlxreg_lc *mlxreg_lc = platform_get_drvdata(pdev);
 
+	mlxreg_lc_state_update_locked(mlxreg_lc, MLXREG_LC_INITIALIZED, 0);
+
 	/*
 	 * Probing and removing are invoked by hotplug events raised upon line card insertion and
 	 * removing. If probing procedure fails all data is cleared. However, hotplug event still
-- 
2.20.1

[PATCH platform 3/4] platform/mellanox: Remove unnecessary code

[Vadim Pasternak]

Remove redundant 'NULL' check for of if 'data->notifier'.

Replace 'return err' by 'return 0' in mlxreg_lc_probe().

Fixes: 62f9529b8d5c87b ("platform/mellanox: mlxreg-lc: Add initial support for Nvidia line card devices")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Vadim Pasternak <vadimp@nvidia.com>
---
 drivers/platform/mellanox/mlxreg-lc.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/drivers/platform/mellanox/mlxreg-lc.c b/drivers/platform/mellanox/mlxreg-lc.c
index e578c7bc060b..1e0c3ddc46cd 100644
--- a/drivers/platform/mellanox/mlxreg-lc.c
+++ b/drivers/platform/mellanox/mlxreg-lc.c
@@ -825,10 +825,9 @@ static int mlxreg_lc_probe(struct platform_device *pdev)
 
 	mutex_init(&mlxreg_lc->lock);
 	/* Set event notification callback. */
-	if (data->notifier) {
-		data->notifier->user_handler = mlxreg_lc_event_handler;
-		data->notifier->handle = mlxreg_lc;
-	}
+	data->notifier->user_handler = mlxreg_lc_event_handler;
+	data->notifier->handle = mlxreg_lc;
+
 	data->hpdev.adapter = i2c_get_adapter(data->hpdev.nr);
 	if (!data->hpdev.adapter) {
 		dev_err(&pdev->dev, "Failed to get adapter for bus %d\n",
@@ -888,7 +887,7 @@ static int mlxreg_lc_probe(struct platform_device *pdev)
 	if (err)
 		goto mlxreg_lc_config_init_fail;
 
-	return err;
+	return 0;
 
 mlxreg_lc_config_init_fail:
 regcache_sync_fail:
-- 
2.20.1

[PATCH platform 4/4] platform/mellanox: Remove redundant 'NULL' check

[Vadim Pasternak]

Remove 'NULL' check for 'data->hpdev.client' in error flow of
mlxreg_lc_probe(). It cannot be 'NULL' at this point.

Fixes: b4b830a34d80  ("platform/mellanox: mlxreg-lc: Fix error flow and extend verbosity")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Vadim Pasternak <vadimp@nvidia.com>
---
 drivers/platform/mellanox/mlxreg-lc.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/platform/mellanox/mlxreg-lc.c b/drivers/platform/mellanox/mlxreg-lc.c
index 1e0c3ddc46cd..1e071df4c9f5 100644
--- a/drivers/platform/mellanox/mlxreg-lc.c
+++ b/drivers/platform/mellanox/mlxreg-lc.c
@@ -893,10 +893,8 @@ static int mlxreg_lc_probe(struct platform_device *pdev)
 regcache_sync_fail:
 regmap_write_fail:
 devm_regmap_init_i2c_fail:
-	if (data->hpdev.client) {
-		i2c_unregister_device(data->hpdev.client);
-		data->hpdev.client = NULL;
-	}
+	i2c_unregister_device(data->hpdev.client);
+	data->hpdev.client = NULL;
 i2c_new_device_fail:
 	i2c_put_adapter(data->hpdev.adapter);
 	data->hpdev.adapter = NULL;
-- 
2.20.1

Re: [PATCH platform 0/4] Fixes for issues with coverity, locking, redundant checks

[Hans de Goede]

Hi All,

On 8/23/22 22:19, Vadim Pasternak wrote:
> The patch set includes fixes for several issues:
> Patch #1: fixes coverity issue.
> Patch #2: fixes locking dependency issue.
> Patches #3-#4: remove unnecessary code.

Thank you for your patch-series, I've applied the series to my
review-hans branch:
https://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86.git/log/?h=review-hans

I will also send this out as part of my next fixes
pull-req for 6.0-rc#.

Note I do have one code-style remark to patch 2/4,
since I want to add this to my fixes pull-req I've
taken 2/4 as is. Please send a follow-up (incremental)
patch addressing the code-style issue. See my reply
to patch 2/4.

Regards,

Hans


> 
> Vadim Pasternak (4):
>   platform/mellanox: mlxreg-lc: Fix coverity warning
>   platform/mellanox: mlxreg-lc: Fix locking issue
>   platform/mellanox: Remove unnecessary code
>   platform/mellanox: Remove redundant 'NULL' check
> 
>  drivers/platform/mellanox/mlxreg-lc.c | 53 ++++++++++++++++-----------
>  1 file changed, 31 insertions(+), 22 deletions(-)
> 

Re: [PATCH platform 2/4] platform/mellanox: mlxreg-lc: Fix locking issue

[Hans de Goede]

Hi,

On 8/23/22 22:19, Vadim Pasternak wrote:
> Fix locking issues:
> - mlxreg_lc_state_update() takes a lock when set or clear
>   "MLXREG_LC_POWERED".
> - All the devices can be deleted before MLXREG_LC_POWERED flag is cleared.
> 
> To fix it:
> - Add lock() / unlock() at the beginning / end of
>   mlxreg_lc_event_handler() and remove locking from
>   mlxreg_lc_power_on_off() and mlxreg_lc_enable_disable()
> - Add locked version of mlxreg_lc_state_update() -
>   mlxreg_lc_state_update_locked() for using outside
>   mlxreg_lc_event_handler().
> 
> (2) Remove redundant NULL check for of if 'data->notifier'.
> 
> Fixes: 62f9529b8d5c87b ("platform/mellanox: mlxreg-lc: Add initial support for Nvidia line card devices")
> Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
> Signed-off-by: Vadim Pasternak <vadimp@nvidia.com>
> ---
>  drivers/platform/mellanox/mlxreg-lc.c | 37 ++++++++++++++++++---------
>  1 file changed, 25 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/platform/mellanox/mlxreg-lc.c b/drivers/platform/mellanox/mlxreg-lc.c
> index 9a1bfcd24317..e578c7bc060b 100644
> --- a/drivers/platform/mellanox/mlxreg-lc.c
> +++ b/drivers/platform/mellanox/mlxreg-lc.c
> @@ -460,8 +460,6 @@ static int mlxreg_lc_power_on_off(struct mlxreg_lc *mlxreg_lc, u8 action)
>  	u32 regval;
>  	int err;
>  
> -	mutex_lock(&mlxreg_lc->lock);
> -
>  	err = regmap_read(mlxreg_lc->par_regmap, mlxreg_lc->data->reg_pwr, &regval);
>  	if (err)
>  		goto regmap_read_fail;
> @@ -474,7 +472,6 @@ static int mlxreg_lc_power_on_off(struct mlxreg_lc *mlxreg_lc, u8 action)
>  	err = regmap_write(mlxreg_lc->par_regmap, mlxreg_lc->data->reg_pwr, regval);
>  
>  regmap_read_fail:
> -	mutex_unlock(&mlxreg_lc->lock);
>  	return err;
>  }
>  
> @@ -491,8 +488,6 @@ static int mlxreg_lc_enable_disable(struct mlxreg_lc *mlxreg_lc, bool action)
>  	 * line card which is already has been enabled. Disabling does not affect the disabled line
>  	 * card.
>  	 */
> -	mutex_lock(&mlxreg_lc->lock);
> -
>  	err = regmap_read(mlxreg_lc->par_regmap, mlxreg_lc->data->reg_ena, &regval);
>  	if (err)
>  		goto regmap_read_fail;
> @@ -505,7 +500,6 @@ static int mlxreg_lc_enable_disable(struct mlxreg_lc *mlxreg_lc, bool action)
>  	err = regmap_write(mlxreg_lc->par_regmap, mlxreg_lc->data->reg_ena, regval);
>  
>  regmap_read_fail:
> -	mutex_unlock(&mlxreg_lc->lock);
>  	return err;
>  }
>  
> @@ -537,6 +531,15 @@ mlxreg_lc_sn4800_c16_config_init(struct mlxreg_lc *mlxreg_lc, void *regmap,
>  
>  static void
>  mlxreg_lc_state_update(struct mlxreg_lc *mlxreg_lc, enum mlxreg_lc_state state, u8 action)
> +{
> +	if (action)
> +		mlxreg_lc->state |= state;
> +	else
> +		mlxreg_lc->state &= ~state;
> +}
> +
> +static void
> +mlxreg_lc_state_update_locked(struct mlxreg_lc *mlxreg_lc, enum mlxreg_lc_state state, u8 action)
>  {
>  	mutex_lock(&mlxreg_lc->lock);
>  
> @@ -560,8 +563,11 @@ static int mlxreg_lc_event_handler(void *handle, enum mlxreg_hotplug_kind kind,
>  	dev_info(mlxreg_lc->dev, "linecard#%d state %d event kind %d action %d\n",
>  		 mlxreg_lc->data->slot, mlxreg_lc->state, kind, action);
>  
> -	if (!(mlxreg_lc->state & MLXREG_LC_INITIALIZED))
> +	mutex_lock(&mlxreg_lc->lock);
> +	if (!(mlxreg_lc->state & MLXREG_LC_INITIALIZED)) {
> +		mutex_unlock(&mlxreg_lc->lock);

So here you are unlocking before return.

>  		return 0;
> +	}
>  
>  	switch (kind) {
>  	case MLXREG_HOTPLUG_LC_SYNCED:
> @@ -574,7 +580,7 @@ static int mlxreg_lc_event_handler(void *handle, enum mlxreg_hotplug_kind kind,
>  		if (!(mlxreg_lc->state & MLXREG_LC_POWERED) && action) {
>  			err = mlxreg_lc_power_on_off(mlxreg_lc, 1);
>  			if (err)
> -				return err;
> +				goto mlxreg_lc_power_on_off_fail;

Yet here you use a goto (better IMHO).

>  		}
>  		/* In case line card is configured - enable it. */
>  		if (mlxreg_lc->state & MLXREG_LC_CONFIGURED && action)
> @@ -588,12 +594,13 @@ static int mlxreg_lc_event_handler(void *handle, enum mlxreg_hotplug_kind kind,
>  				/* In case line card is configured - enable it. */
>  				if (mlxreg_lc->state & MLXREG_LC_CONFIGURED)
>  					err = mlxreg_lc_enable_disable(mlxreg_lc, 1);
> +				mutex_unlock(&mlxreg_lc->lock);

and here is another unlocking before return.

>  				return err;
>  			}
>  			err = mlxreg_lc_create_static_devices(mlxreg_lc, mlxreg_lc->main_devs,
>  							      mlxreg_lc->main_devs_num);
>  			if (err)
> -				return err;
> +				goto mlxreg_lc_create_static_devices_fail;

and here is an other goto.

This is not very consistent. Can you please switch to goto-s everywhere?
Preferable with just a simply single "out" label?

I always prefer the goto-s here so that the function has a single
entry + exit point and we can easily see that the lock + unlock
is balanced since there is only 1 of each.

Regards,

Hans




>  
>  			/* In case line card is already in ready state - enable it. */
>  			if (mlxreg_lc->state & MLXREG_LC_CONFIGURED)
> @@ -620,6 +627,10 @@ static int mlxreg_lc_event_handler(void *handle, enum mlxreg_hotplug_kind kind,
>  		break;
>  	}
>  
> +mlxreg_lc_power_on_off_fail:
> +mlxreg_lc_create_static_devices_fail:
> +	mutex_unlock(&mlxreg_lc->lock);
> +
>  	return err;
>  }
>  
> @@ -665,7 +676,7 @@ static int mlxreg_lc_completion_notify(void *handle, struct i2c_adapter *parent,
>  		if (err)
>  			goto mlxreg_lc_create_static_devices_failed;
>  
> -		mlxreg_lc_state_update(mlxreg_lc, MLXREG_LC_POWERED, 1);
> +		mlxreg_lc_state_update_locked(mlxreg_lc, MLXREG_LC_POWERED, 1);
>  	}
>  
>  	/* Verify if line card is synchronized. */
> @@ -676,7 +687,7 @@ static int mlxreg_lc_completion_notify(void *handle, struct i2c_adapter *parent,
>  	/* Power on line card if necessary. */
>  	if (regval & mlxreg_lc->data->mask) {
>  		mlxreg_lc->state |= MLXREG_LC_SYNCED;
> -		mlxreg_lc_state_update(mlxreg_lc, MLXREG_LC_SYNCED, 1);
> +		mlxreg_lc_state_update_locked(mlxreg_lc, MLXREG_LC_SYNCED, 1);
>  		if (mlxreg_lc->state & ~MLXREG_LC_POWERED) {
>  			err = mlxreg_lc_power_on_off(mlxreg_lc, 1);
>  			if (err)
> @@ -684,7 +695,7 @@ static int mlxreg_lc_completion_notify(void *handle, struct i2c_adapter *parent,
>  		}
>  	}
>  
> -	mlxreg_lc_state_update(mlxreg_lc, MLXREG_LC_INITIALIZED, 1);
> +	mlxreg_lc_state_update_locked(mlxreg_lc, MLXREG_LC_INITIALIZED, 1);
>  
>  	return 0;
>  
> @@ -904,6 +915,8 @@ static int mlxreg_lc_remove(struct platform_device *pdev)
>  	struct mlxreg_core_data *data = dev_get_platdata(&pdev->dev);
>  	struct mlxreg_lc *mlxreg_lc = platform_get_drvdata(pdev);
>  
> +	mlxreg_lc_state_update_locked(mlxreg_lc, MLXREG_LC_INITIALIZED, 0);
> +
>  	/*
>  	 * Probing and removing are invoked by hotplug events raised upon line card insertion and
>  	 * removing. If probing procedure fails all data is cleared. However, hotplug event still