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

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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@xxxxxx>
---
  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);




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