1 files changed, 129 insertions, 63 deletions

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 048ff98dbdfd..94865c9d8adc 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -552,7 +552,7 @@ void device_link_wait_removal(void)
 }
 EXPORT_SYMBOL_GPL(device_link_wait_removal);
 
-static struct class devlink_class = {
+static const struct class devlink_class = {
 	.name = "devlink",
 	.dev_groups = devlink_groups,
 	.dev_release = devlink_dev_release,
@@ -1971,7 +1971,7 @@ static struct device *fwnode_get_next_parent_dev(const struct fwnode_handle *fwn
 
 /**
  * __fw_devlink_relax_cycles - Relax and mark dependency cycles.
- * @con: Potential consumer device.
+ * @con_handle: Potential consumer device fwnode.
  * @sup_handle: Potential supplier's fwnode.
  *
  * Needs to be called with fwnode_lock and device link lock held.
@@ -1989,10 +1989,10 @@ static struct device *fwnode_get_next_parent_dev(const struct fwnode_handle *fwn
  *
  * Return true if one or more cycles were found. Otherwise, return false.
  */
-static bool __fw_devlink_relax_cycles(struct device *con,
+static bool __fw_devlink_relax_cycles(struct fwnode_handle *con_handle,
 				 struct fwnode_handle *sup_handle)
 {
-	struct device *sup_dev = NULL, *par_dev = NULL;
+	struct device *sup_dev = NULL, *par_dev = NULL, *con_dev = NULL;
 	struct fwnode_link *link;
 	struct device_link *dev_link;
 	bool ret = false;
@@ -2009,22 +2009,22 @@ static bool __fw_devlink_relax_cycles(struct device *con,
 
 	sup_handle->flags |= FWNODE_FLAG_VISITED;
 
-	sup_dev = get_dev_from_fwnode(sup_handle);
-
 	/* Termination condition. */
-	if (sup_dev == con) {
+	if (sup_handle == con_handle) {
 		pr_debug("----- cycle: start -----\n");
 		ret = true;
 		goto out;
 	}
 
+	sup_dev = get_dev_from_fwnode(sup_handle);
+	con_dev = get_dev_from_fwnode(con_handle);
 	/*
 	 * If sup_dev is bound to a driver and @con hasn't started binding to a
 	 * driver, sup_dev can't be a consumer of @con. So, no need to check
 	 * further.
 	 */
 	if (sup_dev && sup_dev->links.status ==  DL_DEV_DRIVER_BOUND &&
-	    con->links.status == DL_DEV_NO_DRIVER) {
+	    con_dev && con_dev->links.status == DL_DEV_NO_DRIVER) {
 		ret = false;
 		goto out;
 	}
@@ -2033,7 +2033,7 @@ static bool __fw_devlink_relax_cycles(struct device *con,
 		if (link->flags & FWLINK_FLAG_IGNORE)
 			continue;
 
-		if (__fw_devlink_relax_cycles(con, link->supplier)) {
+		if (__fw_devlink_relax_cycles(con_handle, link->supplier)) {
 			__fwnode_link_cycle(link);
 			ret = true;
 		}
@@ -2048,7 +2048,7 @@ static bool __fw_devlink_relax_cycles(struct device *con,
 	else
 		par_dev = fwnode_get_next_parent_dev(sup_handle);
 
-	if (par_dev && __fw_devlink_relax_cycles(con, par_dev->fwnode)) {
+	if (par_dev && __fw_devlink_relax_cycles(con_handle, par_dev->fwnode)) {
 		pr_debug("%pfwf: cycle: child of %pfwf\n", sup_handle,
 			 par_dev->fwnode);
 		ret = true;
@@ -2066,7 +2066,7 @@ static bool __fw_devlink_relax_cycles(struct device *con,
 		    !(dev_link->flags & DL_FLAG_CYCLE))
 			continue;
 
-		if (__fw_devlink_relax_cycles(con,
+		if (__fw_devlink_relax_cycles(con_handle,
 					      dev_link->supplier->fwnode)) {
 			pr_debug("%pfwf: cycle: depends on %pfwf\n", sup_handle,
 				 dev_link->supplier->fwnode);
@@ -2114,11 +2114,6 @@ static int fw_devlink_create_devlink(struct device *con,
 	if (link->flags & FWLINK_FLAG_IGNORE)
 		return 0;
 
-	if (con->fwnode == link->consumer)
-		flags = fw_devlink_get_flags(link->flags);
-	else
-		flags = FW_DEVLINK_FLAGS_PERMISSIVE;
-
 	/*
 	 * In some cases, a device P might also be a supplier to its child node
 	 * C. However, this would defer the probe of C until the probe of P
@@ -2139,25 +2134,23 @@ static int fw_devlink_create_devlink(struct device *con,
 		return -EINVAL;
 
 	/*
-	 * SYNC_STATE_ONLY device links don't block probing and supports cycles.
-	 * So, one might expect that cycle detection isn't necessary for them.
-	 * However, if the device link was marked as SYNC_STATE_ONLY because
-	 * it's part of a cycle, then we still need to do cycle detection. This
-	 * is because the consumer and supplier might be part of multiple cycles
-	 * and we need to detect all those cycles.
+	 * Don't try to optimize by not calling the cycle detection logic under
+	 * certain conditions. There's always some corner case that won't get
+	 * detected.
 	 */
-	if (!device_link_flag_is_sync_state_only(flags) ||
-	    flags & DL_FLAG_CYCLE) {
-		device_links_write_lock();
-		if (__fw_devlink_relax_cycles(con, sup_handle)) {
-			__fwnode_link_cycle(link);
-			flags = fw_devlink_get_flags(link->flags);
-			pr_debug("----- cycle: end -----\n");
-			dev_info(con, "Fixed dependency cycle(s) with %pfwf\n",
-				 sup_handle);
-		}
-		device_links_write_unlock();
+	device_links_write_lock();
+	if (__fw_devlink_relax_cycles(link->consumer, sup_handle)) {
+		__fwnode_link_cycle(link);
+		pr_debug("----- cycle: end -----\n");
+		pr_info("%pfwf: Fixed dependency cycle(s) with %pfwf\n",
+			link->consumer, sup_handle);
 	}
+	device_links_write_unlock();
+
+	if (con->fwnode == link->consumer)
+		flags = fw_devlink_get_flags(link->flags);
+	else
+		flags = FW_DEVLINK_FLAGS_PERMISSIVE;
 
 	if (sup_handle->flags & FWNODE_FLAG_NOT_DEVICE)
 		sup_dev = fwnode_get_next_parent_dev(sup_handle);
@@ -2180,8 +2173,8 @@ static int fw_devlink_create_devlink(struct device *con,
 		}
 
 		if (con != sup_dev && !device_link_add(con, sup_dev, flags)) {
-			dev_err(con, "Failed to create device link (0x%x) with %s\n",
-				flags, dev_name(sup_dev));
+			dev_err(con, "Failed to create device link (0x%x) with supplier %s for %pfwf\n",
+				flags, dev_name(sup_dev), link->consumer);
 			ret = -EINVAL;
 		}
 
@@ -5012,6 +5005,49 @@ define_dev_printk_level(_dev_info, KERN_INFO);
 
 #endif
 
+static void __dev_probe_failed(const struct device *dev, int err, bool fatal,
+			       const char *fmt, va_list vargsp)
+{
+	struct va_format vaf;
+	va_list vargs;
+
+	/*
+	 * On x86_64 and possibly on other architectures, va_list is actually a
+	 * size-1 array containing a structure.  As a result, function parameter
+	 * vargsp decays from T[1] to T*, and &vargsp has type T** rather than
+	 * T(*)[1], which is expected by its assignment to vaf.va below.
+	 *
+	 * One standard way to solve this mess is by creating a copy in a local
+	 * variable of type va_list and then using a pointer to that local copy
+	 * instead, which is the approach employed here.
+	 */
+	va_copy(vargs, vargsp);
+
+	vaf.fmt = fmt;
+	vaf.va = &vargs;
+
+	switch (err) {
+	case -EPROBE_DEFER:
+		device_set_deferred_probe_reason(dev, &vaf);
+		dev_dbg(dev, "error %pe: %pV", ERR_PTR(err), &vaf);
+		break;
+
+	case -ENOMEM:
+		/* Don't print anything on -ENOMEM, there's already enough output */
+		break;
+
+	default:
+		/* Log fatal final failures as errors, otherwise produce warnings */
+		if (fatal)
+			dev_err(dev, "error %pe: %pV", ERR_PTR(err), &vaf);
+		else
+			dev_warn(dev, "error %pe: %pV", ERR_PTR(err), &vaf);
+		break;
+	}
+
+	va_end(vargs);
+}
+
 /**
  * dev_err_probe - probe error check and log helper
  * @dev: the pointer to the struct device
@@ -5024,7 +5060,7 @@ define_dev_printk_level(_dev_info, KERN_INFO);
  * -EPROBE_DEFER and propagate error upwards.
  * In case of -EPROBE_DEFER it sets also defer probe reason, which can be
  * checked later by reading devices_deferred debugfs attribute.
- * It replaces code sequence::
+ * It replaces the following code sequence::
  *
  * 	if (err != -EPROBE_DEFER)
  * 		dev_err(dev, ...);
@@ -5036,47 +5072,77 @@ define_dev_printk_level(_dev_info, KERN_INFO);
  *
  * 	return dev_err_probe(dev, err, ...);
  *
- * Using this helper in your probe function is totally fine even if @err is
- * known to never be -EPROBE_DEFER.
+ * Using this helper in your probe function is totally fine even if @err
+ * is known to never be -EPROBE_DEFER.
  * The benefit compared to a normal dev_err() is the standardized format
- * of the error code, it being emitted symbolically (i.e. you get "EAGAIN"
- * instead of "-35") and the fact that the error code is returned which allows
- * more compact error paths.
+ * of the error code, which is emitted symbolically (i.e. you get "EAGAIN"
+ * instead of "-35"), and having the error code returned allows more
+ * compact error paths.
  *
  * Returns @err.
  */
 int dev_err_probe(const struct device *dev, int err, const char *fmt, ...)
 {
-	struct va_format vaf;
-	va_list args;
+	va_list vargs;
 
-	va_start(args, fmt);
-	vaf.fmt = fmt;
-	vaf.va = &args;
+	va_start(vargs, fmt);
 
-	switch (err) {
-	case -EPROBE_DEFER:
-		device_set_deferred_probe_reason(dev, &vaf);
-		dev_dbg(dev, "error %pe: %pV", ERR_PTR(err), &vaf);
-		break;
+	/* Use dev_err() for logging when err doesn't equal -EPROBE_DEFER */
+	__dev_probe_failed(dev, err, true, fmt, vargs);
 
-	case -ENOMEM:
-		/*
-		 * We don't print anything on -ENOMEM, there is already enough
-		 * output.
-		 */
-		break;
+	va_end(vargs);
 
-	default:
-		dev_err(dev, "error %pe: %pV", ERR_PTR(err), &vaf);
-		break;
-	}
+	return err;
+}
+EXPORT_SYMBOL_GPL(dev_err_probe);
 
-	va_end(args);
+/**
+ * dev_warn_probe - probe error check and log helper
+ * @dev: the pointer to the struct device
+ * @err: error value to test
+ * @fmt: printf-style format string
+ * @...: arguments as specified in the format string
+ *
+ * This helper implements common pattern present in probe functions for error
+ * checking: print debug or warning message depending if the error value is
+ * -EPROBE_DEFER and propagate error upwards.
+ * In case of -EPROBE_DEFER it sets also defer probe reason, which can be
+ * checked later by reading devices_deferred debugfs attribute.
+ * It replaces the following code sequence::
+ *
+ * 	if (err != -EPROBE_DEFER)
+ * 		dev_warn(dev, ...);
+ * 	else
+ * 		dev_dbg(dev, ...);
+ * 	return err;
+ *
+ * with::
+ *
+ * 	return dev_warn_probe(dev, err, ...);
+ *
+ * Using this helper in your probe function is totally fine even if @err
+ * is known to never be -EPROBE_DEFER.
+ * The benefit compared to a normal dev_warn() is the standardized format
+ * of the error code, which is emitted symbolically (i.e. you get "EAGAIN"
+ * instead of "-35"), and having the error code returned allows more
+ * compact error paths.
+ *
+ * Returns @err.
+ */
+int dev_warn_probe(const struct device *dev, int err, const char *fmt, ...)
+{
+	va_list vargs;
+
+	va_start(vargs, fmt);
+
+	/* Use dev_warn() for logging when err doesn't equal -EPROBE_DEFER */
+	__dev_probe_failed(dev, err, false, fmt, vargs);
+
+	va_end(vargs);
 
 	return err;
 }
-EXPORT_SYMBOL_GPL(dev_err_probe);
+EXPORT_SYMBOL_GPL(dev_warn_probe);
 
 static inline bool fwnode_is_primary(struct fwnode_handle *fwnode)
 {