To improve detection and handling of dependency cycles, we need to be
able to mark fwnode links as being part of cycles. fwnode links marked
as being part of a cycle should not block their consumers from probing.
Fixes: 2de9d8e0d2fe ("driver core: fw_devlink: Improve handling of cyclic dependencies")
Signed-off-by: Saravana Kannan <saravanak@xxxxxxxxxx>
Tested-by: Colin Foster <colin.foster@xxxxxxxxxxxxxxxx>
Tested-by: Sudeep Holla <sudeep.holla@xxxxxxx>
---
drivers/base/core.c | 50 +++++++++++++++++++++++++++++++++---------
include/linux/fwnode.h | 11 +++++++++-
2 files changed, 50 insertions(+), 11 deletions(-)
diff --git a/drivers/base/core.c b/drivers/base/core.c
index 071c454844d6..4869b6fdfeaf 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -76,13 +76,15 @@ static bool fw_devlink_best_effort;
* are ignored and there is no reference counting.
*/
static int __fwnode_link_add(struct fwnode_handle *con,
- struct fwnode_handle *sup)
+ struct fwnode_handle *sup, u8 flags)
{
struct fwnode_link *link;
list_for_each_entry(link, &sup->consumers, s_hook)
- if (link->consumer == con)
+ if (link->consumer == con) {
+ link->flags |= flags;
return 0;
+ }
link = kzalloc(sizeof(*link), GFP_KERNEL);
if (!link)
@@ -92,6 +94,7 @@ static int __fwnode_link_add(struct fwnode_handle *con,
INIT_LIST_HEAD(&link->s_hook);
link->consumer = con;
INIT_LIST_HEAD(&link->c_hook);
+ link->flags = flags;
list_add(&link->s_hook, &sup->consumers);
list_add(&link->c_hook, &con->suppliers);
@@ -106,7 +109,7 @@ int fwnode_link_add(struct fwnode_handle *con, struct fwnode_handle *sup)
int ret;
mutex_lock(&fwnode_link_lock);
- ret = __fwnode_link_add(con, sup);
+ ret = __fwnode_link_add(con, sup, 0);
mutex_unlock(&fwnode_link_lock);
return ret;
}
@@ -126,6 +129,19 @@ static void __fwnode_link_del(struct fwnode_link *link)
kfree(link);
}
+/**
+ * __fwnode_link_cycle - Mark a fwnode link as being part of a cycle.
+ * @link: the fwnode_link to be marked
+ *
+ * The fwnode_link_lock needs to be held when this function is called.
+ */
+static void __fwnode_link_cycle(struct fwnode_link *link)
+{
+ pr_debug("%pfwf: Relaxing link with %pfwf\n",
+ link->consumer, link->supplier);
+ link->flags |= FWLINK_FLAG_CYCLE;
+}
+
/**
* fwnode_links_purge_suppliers - Delete all supplier links of fwnode_handle.
* @fwnode: fwnode whose supplier links need to be deleted
@@ -199,7 +215,7 @@ static void __fwnode_links_move_consumers(struct fwnode_handle *from,
struct fwnode_link *link, *tmp;
list_for_each_entry_safe(link, tmp, &from->consumers, s_hook) {
- __fwnode_link_add(link->consumer, to);
+ __fwnode_link_add(link->consumer, to, link->flags);
__fwnode_link_del(link);
}
}
@@ -1041,6 +1057,21 @@ static bool dev_is_best_effort(struct device *dev)
(dev->fwnode && (dev->fwnode->flags & FWNODE_FLAG_BEST_EFFORT));
}
+static struct fwnode_handle *fwnode_links_check_suppliers(
+ struct fwnode_handle *fwnode)
+{
+ struct fwnode_link *link;
+
+ if (!fwnode || fw_devlink_is_permissive())
+ return NULL;
+
+ list_for_each_entry(link, &fwnode->suppliers, c_hook)
+ if (!(link->flags & FWLINK_FLAG_CYCLE))
+ return link->supplier;
+
+ return NULL;
+}
+
/**
* device_links_check_suppliers - Check presence of supplier drivers.
* @dev: Consumer device.
@@ -1068,11 +1099,8 @@ int device_links_check_suppliers(struct device *dev)
* probe.
*/
mutex_lock(&fwnode_link_lock);
- if (dev->fwnode && !list_empty(&dev->fwnode->suppliers) &&
- !fw_devlink_is_permissive()) {
- sup_fw = list_first_entry(&dev->fwnode->suppliers,
- struct fwnode_link,
- c_hook)->supplier;
+ sup_fw = fwnode_links_check_suppliers(dev->fwnode);
+ if (sup_fw) {
if (!dev_is_best_effort(dev)) {
fwnode_ret = -EPROBE_DEFER;
dev_err_probe(dev, -EPROBE_DEFER,
@@ -1261,7 +1289,9 @@ static ssize_t waiting_for_supplier_show(struct device *dev,
bool val;
device_lock(dev);
- val = !list_empty(&dev->fwnode->suppliers);
+ mutex_lock(&fwnode_link_lock);
+ val = !!fwnode_links_check_suppliers(dev->fwnode);
+ mutex_unlock(&fwnode_link_lock);
device_unlock(dev);
return sysfs_emit(buf, "%u\n", val);
}
diff --git a/include/linux/fwnode.h b/include/linux/fwnode.h
index 89b9bdfca925..fdf2ee0285b7 100644
--- a/include/linux/fwnode.h
+++ b/include/linux/fwnode.h
@@ -18,7 +18,7 @@ struct fwnode_operations;
struct device;
/*
- * fwnode link flags
+ * fwnode flags
*
* LINKS_ADDED: The fwnode has already be parsed to add fwnode links.
* NOT_DEVICE: The fwnode will never be populated as a struct device.
@@ -36,6 +36,7 @@ struct device;
#define FWNODE_FLAG_INITIALIZED BIT(2)
#define FWNODE_FLAG_NEEDS_CHILD_BOUND_ON_ADD BIT(3)
#define FWNODE_FLAG_BEST_EFFORT BIT(4)
+#define FWNODE_FLAG_VISITED BIT(5)
struct fwnode_handle {
struct fwnode_handle *secondary;
@@ -46,11 +47,19 @@ struct fwnode_handle {
u8 flags;
};
+/*
+ * fwnode link flags
+ *
+ * CYCLE: The fwnode link is part of a cycle. Don't defer probe.
+ */
+#define FWLINK_FLAG_CYCLE BIT(0)
+
struct fwnode_link {
struct fwnode_handle *supplier;
struct list_head s_hook;
struct fwnode_handle *consumer;
struct list_head c_hook;
+ u8 flags;
};
/**
--
2.39.1.519.gcb327c4b5f-goog
