From: Saravana Kannan saravanak@google.com
[ Upstream commit 6a6dfdf8b3ff337be5a447e9f4e71969f18370ad ]
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@google.com Tested-by: Colin Foster colin.foster@in-advantage.com Tested-by: Sudeep Holla sudeep.holla@arm.com Tested-by: Douglas Anderson dianders@chromium.org Tested-by: Geert Uytterhoeven geert+renesas@glider.be Tested-by: Luca Weiss luca.weiss@fairphone.com # qcom/sm7225-fairphone-fp4 Link: https://lore.kernel.org/r/20230207014207.1678715-7-saravanak@google.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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 d74a07ca36dff..24c48fe3a0252 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -75,13 +75,15 @@ 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) @@ -91,6 +93,7 @@ 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); @@ -105,7 +108,7 @@ 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; } @@ -125,6 +128,19 @@ 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 @@ -198,7 +214,7 @@ 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); } } @@ -1040,6 +1056,21 @@ 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. @@ -1067,11 +1098,8 @@ 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, @@ -1260,7 +1288,9 @@ 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 89b9bdfca925c..fdf2ee0285b7a 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; };
/**