[PATCH v4 1/4] devres: Make locking straight forward in release_nodes()

Andy Shevchenko
2021-05-17T12:29:37Z

It seems for the sake of saving stack memory of couple of pointers,
the locking in release_nodes() callers becomes interesting.

Replace this logic with a straight forward locking and unlocking scheme.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
v4: rebased on top of v5.13-rc2
drivers/base/devres.c | 30 +++++++++++++++---------------
1 file changed, 15 insertions(+), 15 deletions(-)

diff --git a/drivers/base/devres.c b/drivers/base/devres.c
index 8746f2212781..7970217191e0 100644
--- a/drivers/base/devres.c
+++ b/drivers/base/devres.c
@@ -503,28 +503,18 @@ static int remove_nodes(struct device *dev,
return cnt;
}

-static int release_nodes(struct device *dev, struct list_head *first,
- struct list_head *end, unsigned long flags)
- __releases(&dev->devres_lock)
+static void release_nodes(struct device *dev, struct list_head *todo)
{
- LIST_HEAD(todo);
- int cnt;
struct devres *dr, *tmp;

- cnt = remove_nodes(dev, first, end, &todo);
-
- spin_unlock_irqrestore(&dev->devres_lock, flags);
-
/* Release. Note that both devres and devres_group are
* handled as devres in the following loop. This is safe.
*/
- list_for_each_entry_safe_reverse(dr, tmp, &todo, node.entry) {
+ list_for_each_entry_safe_reverse(dr, tmp, todo, node.entry) {
devres_log(dev, &dr->node, "REL");
dr->node.release(dev, dr->data);
kfree(dr);
}
-
- return cnt;
}

/**
@@ -537,13 +527,19 @@ static int release_nodes(struct device *dev, struct list_head *first,
int devres_release_all(struct device *dev)
{
unsigned long flags;
+ LIST_HEAD(todo);
+ int cnt;

/* Looks like an uninitialized device structure */
if (WARN_ON(dev->devres_head.next == NULL))
return -ENODEV;
+
spin_lock_irqsave(&dev->devres_lock, flags);
- return release_nodes(dev, dev->devres_head.next, &dev->devres_head,
- flags);
+ cnt = remove_nodes(dev, dev->devres_head.next, &dev->devres_head, &todo);
+ spin_unlock_irqrestore(&dev->devres_lock, flags);
+
+ release_nodes(dev, &todo);
+ return cnt;
}

/**
@@ -679,6 +675,7 @@ int devres_release_group(struct device *dev, void *id)
{
struct devres_group *grp;
unsigned long flags;
+ LIST_HEAD(todo);
int cnt = 0;

spin_lock_irqsave(&dev->devres_lock, flags);
@@ -691,7 +688,10 @@ int devres_release_group(struct device *dev, void *id)
if (!list_empty(&grp->node[1].entry))
end = grp->node[1].entry.next;

- cnt = release_nodes(dev, first, end, flags);
+ cnt = remove_nodes(dev, first, end, &todo);
+ spin_unlock_irqrestore(&dev->devres_lock, flags);
+
+ release_nodes(dev, &todo);
} else {
WARN_ON(1);
spin_unlock_irqrestore(&dev->devres_lock, flags);
--
2.30.2