[PATCH v1 06/18] Revert "driver core: fw_devlink: Add support for batching fwnode parsing"

Saravana Kannan
2020-11-04T23:24:33Z

This reverts commit 716a7a25969003d82ab738179c3f1068a120ed11.

Signed-off-by: Saravana Kannan <saravanak@google.com>
---
drivers/base/base.h | 1 -
drivers/base/core.c | 116 +++--------------------------------------
drivers/base/dd.c | 8 ---
include/linux/fwnode.h | 2 -
4 files changed, 7 insertions(+), 120 deletions(-)

diff --git a/drivers/base/base.h b/drivers/base/base.h
index c3562adf4789..91cfb8405abd 100644
--- a/drivers/base/base.h
+++ b/drivers/base/base.h
@@ -156,7 +156,6 @@ extern char *make_class_name(const char *name, struct kobject *kobj);
extern int devres_release_all(struct device *dev);
extern void device_block_probing(void);
extern void device_unblock_probing(void);
-extern void driver_deferred_probe_force_trigger(void);

/* /sys/devices directory */
extern struct kset *devices_kset;
diff --git a/drivers/base/core.c b/drivers/base/core.c
index 6745375a8bb9..31a76159f118 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -50,9 +50,6 @@ static LIST_HEAD(wait_for_suppliers);
static DEFINE_MUTEX(wfs_lock);
static LIST_HEAD(deferred_sync);
static unsigned int defer_sync_state_count = 1;
-static unsigned int defer_fw_devlink_count;
-static DEFINE_MUTEX(defer_fw_devlink_lock);
-static bool fw_devlink_is_permissive(void);

#ifdef CONFIG_SRCU
static DEFINE_MUTEX(device_links_lock);
@@ -758,7 +755,7 @@ static void device_link_add_missing_supplier_links(void)
int ret = fwnode_call_int_op(dev->fwnode, add_links, dev);
if (!ret)
list_del_init(&dev->links.needs_suppliers);
- else if (ret != -ENODEV || fw_devlink_is_permissive())
+ else if (ret != -ENODEV)
dev->links.need_for_probe = false;
}
mutex_unlock(&wfs_lock);
@@ -1444,116 +1441,17 @@ static void fw_devlink_link_device(struct device *dev)
{
int fw_ret;

- if (!fw_devlink_flags)
- return;
-
- mutex_lock(&defer_fw_devlink_lock);
- if (!defer_fw_devlink_count)
- device_link_add_missing_supplier_links();
-
- /*
- * The device's fwnode not having add_links() doesn't affect if other
- * consumers can find this device as a supplier. So, this check is
- * intentionally placed after device_link_add_missing_supplier_links().
- */
- if (!fwnode_has_op(dev->fwnode, add_links))
- goto out;
+ device_link_add_missing_supplier_links();

- /*
- * If fw_devlink is being deferred, assume all devices have mandatory
- * suppliers they need to link to later. Then, when the fw_devlink is
- * resumed, all these devices will get a chance to try and link to any
- * suppliers they have.
- */
- if (!defer_fw_devlink_count) {
+ if (fw_devlink_flags && fwnode_has_op(dev->fwnode, add_links)) {
fw_ret = fwnode_call_int_op(dev->fwnode, add_links, dev);
- if (fw_ret == -ENODEV && fw_devlink_is_permissive())
- fw_ret = -EAGAIN;
- } else {
- fw_ret = -ENODEV;
+ if (fw_ret == -ENODEV && !fw_devlink_is_permissive())
+ device_link_wait_for_mandatory_supplier(dev);
+ else if (fw_ret)
+ device_link_wait_for_optional_supplier(dev);
}
-
- if (fw_ret == -ENODEV)
- device_link_wait_for_mandatory_supplier(dev);
- else if (fw_ret)
- device_link_wait_for_optional_supplier(dev);
-
-out:
- mutex_unlock(&defer_fw_devlink_lock);
}

-/**
- * fw_devlink_pause - Pause parsing of fwnode to create device links
- *
- * Calling this function defers any fwnode parsing to create device links until
- * fw_devlink_resume() is called. Both these functions are ref counted and the
- * caller needs to match the calls.
- *
- * While fw_devlink is paused:
- * - Any device that is added won't have its fwnode parsed to create device
- * links.
- * - The probe of the device will also be deferred during this period.
- * - Any devices that were already added, but waiting for suppliers won't be
- * able to link to newly added devices.
- *
- * Once fw_devlink_resume():
- * - All the fwnodes that was not parsed will be parsed.
- * - All the devices that were deferred probing will be reattempted if they
- * aren't waiting for any more suppliers.
- *
- * This pair of functions, is mainly meant to optimize the parsing of fwnodes
- * when a lot of devices that need to link to each other are added in a short
- * interval of time. For example, adding all the top level devices in a system.
- *
- * For example, if N devices are added and:
- * - All the consumers are added before their suppliers
- * - All the suppliers of the N devices are part of the N devices
- *
- * Then:
- *
- * - With the use of fw_devlink_pause() and fw_devlink_resume(), each device
- * will only need one parsing of its fwnode because it is guaranteed to find
- * all the supplier devices already registered and ready to link to. It won't
- * have to do another pass later to find one or more suppliers it couldn't
- * find in the first parse of the fwnode. So, we'll only need O(N) fwnode
- * parses.
- *
- * - Without the use of fw_devlink_pause() and fw_devlink_resume(), we would
- * end up doing O(N^2) parses of fwnodes because every device that's added is
- * guaranteed to trigger a parse of the fwnode of every device added before
- * it. This O(N^2) parse is made worse by the fact that when a fwnode of a
- * device is parsed, all it descendant devices might need to have their
- * fwnodes parsed too (even if the devices themselves aren't added).
- */
-void fw_devlink_pause(void)
-{
- mutex_lock(&defer_fw_devlink_lock);
- defer_fw_devlink_count++;
- mutex_unlock(&defer_fw_devlink_lock);
-}
-
-/** fw_devlink_resume - Resume parsing of fwnode to create device links
- *
- * This function is used in conjunction with fw_devlink_pause() and is ref
- * counted. See documentation for fw_devlink_pause() for more details.
- */
-void fw_devlink_resume(void)
-{
- mutex_lock(&defer_fw_devlink_lock);
- if (!defer_fw_devlink_count) {
- WARN(true, "Unmatched fw_devlink pause/resume!");
- goto out;
- }
-
- defer_fw_devlink_count--;
- if (defer_fw_devlink_count)
- goto out;
-
- device_link_add_missing_supplier_links();
- driver_deferred_probe_force_trigger();
-out:
- mutex_unlock(&defer_fw_devlink_lock);
-}
/* Device links support end. */

int (*platform_notify)(struct device *dev) = NULL;
diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index ec67b5ffa06d..b42229b74fd6 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -163,14 +163,6 @@ static bool driver_deferred_probe_enable = false;
* again.
*/
static void driver_deferred_probe_trigger(void)
-{
- if (!driver_deferred_probe_enable)
- return;
-
- driver_deferred_probe_force_trigger();
-}
-
-void driver_deferred_probe_force_trigger(void)
{
if (!driver_deferred_probe_enable)
return;
diff --git a/include/linux/fwnode.h b/include/linux/fwnode.h
index 9506f8ec0974..e0abafbb17f8 100644
--- a/include/linux/fwnode.h
+++ b/include/linux/fwnode.h
@@ -171,7 +171,5 @@ struct fwnode_operations {
#define get_dev_from_fwnode(fwnode) get_device((fwnode)->dev)

extern u32 fw_devlink_get_flags(void);
-void fw_devlink_pause(void);
-void fw_devlink_resume(void);

#endif
--
2.29.1.341.ge80a0c044ae-goog