diff mbox series

[02/10] driver core: Better distinguish probe errors in really_probe

Message ID 20210614150846.4111871-3-hch@lst.de (mailing list archive)
State New, archived
Headers show
Series [01/10] driver core: Pull required checks into driver_probe_device() | expand

Commit Message

Christoph Hellwig June 14, 2021, 3:08 p.m. UTC
really_probe tries to special case errors from ->probe, but due to all
other initialization added to the function over time now a lot of
internal errors hit that code path as well.  Untangle that by adding
a new probe_err local variable and apply the special casing only to
that.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/base/dd.c | 72 +++++++++++++++++++++++++++--------------------
 1 file changed, 41 insertions(+), 31 deletions(-)

Comments

Kirti Wankhede June 14, 2021, 6:47 p.m. UTC | #1
On 6/14/2021 8:38 PM, Christoph Hellwig wrote:
> really_probe tries to special case errors from ->probe, but due to all
> other initialization added to the function over time now a lot of
> internal errors hit that code path as well.  Untangle that by adding
> a new probe_err local variable and apply the special casing only to
> that.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>   drivers/base/dd.c | 72 +++++++++++++++++++++++++++--------------------
>   1 file changed, 41 insertions(+), 31 deletions(-)
> 
> diff --git a/drivers/base/dd.c b/drivers/base/dd.c
> index 7477d3322b3a..999bc737a8f0 100644
> --- a/drivers/base/dd.c
> +++ b/drivers/base/dd.c
> @@ -513,12 +513,42 @@ static ssize_t state_synced_show(struct device *dev,
>   }
>   static DEVICE_ATTR_RO(state_synced);
>   
> +
> +static int call_driver_probe(struct device *dev, struct device_driver *drv)
> +{
> +	int ret = 0;
> +
> +	if (dev->bus->probe)
> +		ret = dev->bus->probe(dev);
> +	else if (drv->probe)
> +		ret = drv->probe(dev);
> +
> +	switch (ret) {
> +	case -EPROBE_DEFER:
> +		/* Driver requested deferred probing */
> +		dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
> +		break;
> +	case -ENODEV:
> +	case -ENXIO:
> +		pr_debug("%s: probe of %s rejects match %d\n",
> +			 drv->name, dev_name(dev), ret);
> +		break;
> +	default:
> +		/* driver matched but the probe failed */
> +		pr_warn("%s: probe of %s failed with error %d\n",
> +			drv->name, dev_name(dev), ret);

There should be case 0, that is, success case before default case as below:
+	case 0:
+		/* Driver returned success */
+		break;

Otherwise even in case of success, above warning would mislead that 
probe has failed.

Thanks,
Kirti

> +		break;
> +	}
> +
> +	return ret;
> +}
> +
>   static int really_probe(struct device *dev, struct device_driver *drv)
>   {
> -	int ret = -EPROBE_DEFER;
>   	int local_trigger_count = atomic_read(&deferred_trigger_count);
>   	bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) &&
>   			   !drv->suppress_bind_attrs;
> +	int ret = -EPROBE_DEFER, probe_ret = 0;
>   
>   	if (defer_all_probes) {
>   		/*
> @@ -572,15 +602,15 @@ static int really_probe(struct device *dev, struct device_driver *drv)
>   			goto probe_failed;
>   	}
>   
> -	if (dev->bus->probe) {
> -		ret = dev->bus->probe(dev);
> -		if (ret)
> -			goto probe_failed;
> -	} else if (drv->probe) {
> -		ret = drv->probe(dev);
> -		if (ret)
> -			goto probe_failed;
> -	}
> +	probe_ret = call_driver_probe(dev, drv);
> +	if (probe_ret) {
> +		/*
> +		 * Ignore errors returned by ->probe so that the next driver can
> +		 * try its luck.
> +		   */
> +		ret = 0;
> +		goto probe_failed;
> +	}
>   
>   	if (device_add_groups(dev, drv->dev_groups)) {
>   		dev_err(dev, "device_add_groups() failed\n");
> @@ -650,28 +680,8 @@ static int really_probe(struct device *dev, struct device_driver *drv)
>   		dev->pm_domain->dismiss(dev);
>   	pm_runtime_reinit(dev);
>   	dev_pm_set_driver_flags(dev, 0);
> -
> -	switch (ret) {
> -	case -EPROBE_DEFER:
> -		/* Driver requested deferred probing */
> -		dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
> +	if (probe_ret == -EPROBE_DEFER)
>   		driver_deferred_probe_add_trigger(dev, local_trigger_count);
> -		break;
> -	case -ENODEV:
> -	case -ENXIO:
> -		pr_debug("%s: probe of %s rejects match %d\n",
> -			 drv->name, dev_name(dev), ret);
> -		break;
> -	default:
> -		/* driver matched but the probe failed */
> -		pr_warn("%s: probe of %s failed with error %d\n",
> -			drv->name, dev_name(dev), ret);
> -	}
> -	/*
> -	 * Ignore errors returned by ->probe so that the next driver can try
> -	 * its luck.
> -	 */
> -	ret = 0;
>   done:
>   	atomic_dec(&probe_count);
>   	wake_up_all(&probe_waitqueue);
>
Greg KH June 15, 2021, 5:17 a.m. UTC | #2
On Mon, Jun 14, 2021 at 05:08:38PM +0200, Christoph Hellwig wrote:
> really_probe tries to special case errors from ->probe, but due to all
> other initialization added to the function over time now a lot of
> internal errors hit that code path as well.  Untangle that by adding
> a new probe_err local variable and apply the special casing only to
> that.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  drivers/base/dd.c | 72 +++++++++++++++++++++++++++--------------------
>  1 file changed, 41 insertions(+), 31 deletions(-)
> 
> diff --git a/drivers/base/dd.c b/drivers/base/dd.c
> index 7477d3322b3a..999bc737a8f0 100644
> --- a/drivers/base/dd.c
> +++ b/drivers/base/dd.c
> @@ -513,12 +513,42 @@ static ssize_t state_synced_show(struct device *dev,
>  }
>  static DEVICE_ATTR_RO(state_synced);
>  
> +
> +static int call_driver_probe(struct device *dev, struct device_driver *drv)
> +{
> +	int ret = 0;
> +
> +	if (dev->bus->probe)
> +		ret = dev->bus->probe(dev);
> +	else if (drv->probe)
> +		ret = drv->probe(dev);
> +
> +	switch (ret) {
> +	case -EPROBE_DEFER:
> +		/* Driver requested deferred probing */
> +		dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
> +		break;
> +	case -ENODEV:
> +	case -ENXIO:
> +		pr_debug("%s: probe of %s rejects match %d\n",
> +			 drv->name, dev_name(dev), ret);
> +		break;
> +	default:
> +		/* driver matched but the probe failed */
> +		pr_warn("%s: probe of %s failed with error %d\n",
> +			drv->name, dev_name(dev), ret);
> +		break;
> +	}

Like Kirti said, 0 needs to be handled here.  Did this not spew a lot of
warnings in the logs?

And we can fix up the pr_* calls to use dev_* in the future, shows the
evolution of this code...

thanks,

greg k-h
Christoph Hellwig June 15, 2021, 5:48 a.m. UTC | #3
On Tue, Jun 15, 2021 at 07:17:43AM +0200, Greg Kroah-Hartman wrote:
> Like Kirti said, 0 needs to be handled here.  Did this not spew a lot of
> warnings in the logs?

Trying again it did.  But I didn't even notice given all the crap
printed during a typical boot these days..
diff mbox series

Patch

diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 7477d3322b3a..999bc737a8f0 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -513,12 +513,42 @@  static ssize_t state_synced_show(struct device *dev,
 }
 static DEVICE_ATTR_RO(state_synced);
 
+
+static int call_driver_probe(struct device *dev, struct device_driver *drv)
+{
+	int ret = 0;
+
+	if (dev->bus->probe)
+		ret = dev->bus->probe(dev);
+	else if (drv->probe)
+		ret = drv->probe(dev);
+
+	switch (ret) {
+	case -EPROBE_DEFER:
+		/* Driver requested deferred probing */
+		dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
+		break;
+	case -ENODEV:
+	case -ENXIO:
+		pr_debug("%s: probe of %s rejects match %d\n",
+			 drv->name, dev_name(dev), ret);
+		break;
+	default:
+		/* driver matched but the probe failed */
+		pr_warn("%s: probe of %s failed with error %d\n",
+			drv->name, dev_name(dev), ret);
+		break;
+	}
+
+	return ret;
+}
+
 static int really_probe(struct device *dev, struct device_driver *drv)
 {
-	int ret = -EPROBE_DEFER;
 	int local_trigger_count = atomic_read(&deferred_trigger_count);
 	bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) &&
 			   !drv->suppress_bind_attrs;
+	int ret = -EPROBE_DEFER, probe_ret = 0;
 
 	if (defer_all_probes) {
 		/*
@@ -572,15 +602,15 @@  static int really_probe(struct device *dev, struct device_driver *drv)
 			goto probe_failed;
 	}
 
-	if (dev->bus->probe) {
-		ret = dev->bus->probe(dev);
-		if (ret)
-			goto probe_failed;
-	} else if (drv->probe) {
-		ret = drv->probe(dev);
-		if (ret)
-			goto probe_failed;
-	}
+	probe_ret = call_driver_probe(dev, drv);
+	if (probe_ret) {
+		/*
+		 * Ignore errors returned by ->probe so that the next driver can
+		 * try its luck.
+		   */
+		ret = 0;
+		goto probe_failed;
+	} 
 
 	if (device_add_groups(dev, drv->dev_groups)) {
 		dev_err(dev, "device_add_groups() failed\n");
@@ -650,28 +680,8 @@  static int really_probe(struct device *dev, struct device_driver *drv)
 		dev->pm_domain->dismiss(dev);
 	pm_runtime_reinit(dev);
 	dev_pm_set_driver_flags(dev, 0);
-
-	switch (ret) {
-	case -EPROBE_DEFER:
-		/* Driver requested deferred probing */
-		dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
+	if (probe_ret == -EPROBE_DEFER)
 		driver_deferred_probe_add_trigger(dev, local_trigger_count);
-		break;
-	case -ENODEV:
-	case -ENXIO:
-		pr_debug("%s: probe of %s rejects match %d\n",
-			 drv->name, dev_name(dev), ret);
-		break;
-	default:
-		/* driver matched but the probe failed */
-		pr_warn("%s: probe of %s failed with error %d\n",
-			drv->name, dev_name(dev), ret);
-	}
-	/*
-	 * Ignore errors returned by ->probe so that the next driver can try
-	 * its luck.
-	 */
-	ret = 0;
 done:
 	atomic_dec(&probe_count);
 	wake_up_all(&probe_waitqueue);