From cec72f3efc6272420c2c2c699607f03d09b93e41 Mon Sep 17 00:00:00 2001 From: Saravana Kannan Date: Wed, 1 Jul 2020 12:42:57 -0700 Subject: [PATCH 1/3] driver core: Don't do deferred probe in parallel with kernel_init thread The current deferred probe implementation can mess up suspend/resume ordering if deferred probe thread is kicked off in parallel with the main initcall thread (kernel_init thread) [1]. For example: Say device-B is a consumer of device-A. Initcall thread Deferred probe thread =============== ===================== 1. device-A is added. 2. device-B is added. 3. dpm_list is now [device-A, device-B]. 4. driver-A defers probe of device-A. 5. device-A is moved to end of dpm_list 6. dpm_list is now [device-B, device-A] 7. driver-B is registereed and probes device-B. 8. dpm_list stays as [device-B, device-A]. The reverse order of dpm_list is used for suspend. So in this case device-A would incorrectly get suspended before device-B. Commit 716a7a259690 ("driver core: fw_devlink: Add support for batching fwnode parsing") kicked off the deferred probe thread early during boot to run in parallel with the initcall thread and caused suspend/resume regressions. This patch removes the parallel run of the deferred probe thread to avoid the suspend/resume regressions. [1] - https://lore.kernel.org/lkml/CAGETcx8W96KAw-d_siTX4qHB_-7ddk0miYRDQeHE6E0_8qx-6Q@mail.gmail.com/ Fixes: 716a7a259690 ("driver core: fw_devlink: Add support for batching fwnode parsing") Signed-off-by: Saravana Kannan Tested-by: Geert Uytterhoeven Link: https://lore.kernel.org/r/20200701194259.3337652-2-saravanak@google.com Signed-off-by: Greg Kroah-Hartman --- drivers/base/base.h | 1 - drivers/base/core.c | 1 - drivers/base/dd.c | 5 ----- 3 files changed, 7 deletions(-) diff --git a/drivers/base/base.h b/drivers/base/base.h index 95c22c0f90360..40fb069a8a7e4 100644 --- a/drivers/base/base.h +++ b/drivers/base/base.h @@ -153,7 +153,6 @@ 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 67d39a90b45c7..35cc9896eb9ee 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -1323,7 +1323,6 @@ void fw_devlink_resume(void) goto out; device_link_add_missing_supplier_links(); - driver_deferred_probe_force_trigger(); out: mutex_unlock(&defer_fw_devlink_lock); } diff --git a/drivers/base/dd.c b/drivers/base/dd.c index 9a1d940342ac4..48ca81cb8ebc4 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -164,11 +164,6 @@ 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) -{ /* * A successful probe means that all the devices in the pending list * should be triggered to be reprobed. Move all the deferred devices From ec7bd78498f29680f536451fbdf9464e851273ed Mon Sep 17 00:00:00 2001 From: Saravana Kannan Date: Wed, 1 Jul 2020 12:42:58 -0700 Subject: [PATCH 2/3] driver core: Rename dev_links_info.defer_sync to defer_hook The defer_sync field is used as a hook to add the device to the deferred_sync list. Rename it so that it's more meaningful for the next patch that'll also use this field as a hook to a deferred_fw_devlink list. Signed-off-by: Saravana Kannan Reviewed-by: Rafael J. Wysocki Tested-by: Geert Uytterhoeven Link: https://lore.kernel.org/r/20200701194259.3337652-3-saravanak@google.com Signed-off-by: Greg Kroah-Hartman --- drivers/base/core.c | 22 +++++++++++----------- include/linux/device.h | 4 ++-- 2 files changed, 13 insertions(+), 13 deletions(-) diff --git a/drivers/base/core.c b/drivers/base/core.c index 35cc9896eb9ee..d1d2cdc3a8d89 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -754,11 +754,11 @@ static void __device_links_queue_sync_state(struct device *dev, */ dev->state_synced = true; - if (WARN_ON(!list_empty(&dev->links.defer_sync))) + if (WARN_ON(!list_empty(&dev->links.defer_hook))) return; get_device(dev); - list_add_tail(&dev->links.defer_sync, list); + list_add_tail(&dev->links.defer_hook, list); } /** @@ -776,8 +776,8 @@ static void device_links_flush_sync_list(struct list_head *list, { struct device *dev, *tmp; - list_for_each_entry_safe(dev, tmp, list, links.defer_sync) { - list_del_init(&dev->links.defer_sync); + list_for_each_entry_safe(dev, tmp, list, links.defer_hook) { + list_del_init(&dev->links.defer_hook); if (dev != dont_lock_dev) device_lock(dev); @@ -815,12 +815,12 @@ void device_links_supplier_sync_state_resume(void) if (defer_sync_state_count) goto out; - list_for_each_entry_safe(dev, tmp, &deferred_sync, links.defer_sync) { + list_for_each_entry_safe(dev, tmp, &deferred_sync, links.defer_hook) { /* * Delete from deferred_sync list before queuing it to - * sync_list because defer_sync is used for both lists. + * sync_list because defer_hook is used for both lists. */ - list_del_init(&dev->links.defer_sync); + list_del_init(&dev->links.defer_hook); __device_links_queue_sync_state(dev, &sync_list); } out: @@ -838,8 +838,8 @@ late_initcall(sync_state_resume_initcall); static void __device_links_supplier_defer_sync(struct device *sup) { - if (list_empty(&sup->links.defer_sync) && dev_has_sync_state(sup)) - list_add_tail(&sup->links.defer_sync, &deferred_sync); + if (list_empty(&sup->links.defer_hook) && dev_has_sync_state(sup)) + list_add_tail(&sup->links.defer_hook, &deferred_sync); } static void device_link_drop_managed(struct device_link *link) @@ -1052,7 +1052,7 @@ void device_links_driver_cleanup(struct device *dev) WRITE_ONCE(link->status, DL_STATE_DORMANT); } - list_del_init(&dev->links.defer_sync); + list_del_init(&dev->links.defer_hook); __device_links_no_driver(dev); device_links_write_unlock(); @@ -2171,7 +2171,7 @@ void device_initialize(struct device *dev) INIT_LIST_HEAD(&dev->links.consumers); INIT_LIST_HEAD(&dev->links.suppliers); INIT_LIST_HEAD(&dev->links.needs_suppliers); - INIT_LIST_HEAD(&dev->links.defer_sync); + INIT_LIST_HEAD(&dev->links.defer_hook); dev->links.status = DL_DEV_NO_DRIVER; } EXPORT_SYMBOL_GPL(device_initialize); diff --git a/include/linux/device.h b/include/linux/device.h index 15460a5ac024a..9bb2bc7bb8e33 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -433,7 +433,7 @@ enum dl_dev_state { * @suppliers: List of links to supplier devices. * @consumers: List of links to consumer devices. * @needs_suppliers: Hook to global list of devices waiting for suppliers. - * @defer_sync: Hook to global list of devices that have deferred sync_state. + * @defer_hook: Hook to global list of devices that have deferred sync_state. * @need_for_probe: If needs_suppliers is on a list, this indicates if the * suppliers are needed for probe or not. * @status: Driver status information. @@ -442,7 +442,7 @@ struct dev_links_info { struct list_head suppliers; struct list_head consumers; struct list_head needs_suppliers; - struct list_head defer_sync; + struct list_head defer_hook; bool need_for_probe; enum dl_dev_state status; }; From 2451e746478a6a6e981cfa66b62b791ca93b90c8 Mon Sep 17 00:00:00 2001 From: Saravana Kannan Date: Wed, 1 Jul 2020 12:42:59 -0700 Subject: [PATCH 3/3] driver core: Avoid deferred probe due to fw_devlink_pause/resume() With the earlier patch in this series, all devices that deferred probe due to fw_devlink_pause() will have their probes delayed till the deferred probe thread is kicked off during late_initcall. This will also affect all their consumers. This delayed probing in unnecessary. So this patch just keeps track of the devices that had their probe deferred due to fw_devlink_pause() and attempts to probe them once during fw_devlink_resume(). Fixes: 716a7a259690 ("driver core: fw_devlink: Add support for batching fwnode parsing") Signed-off-by: Saravana Kannan Tested-by: Geert Uytterhoeven Link: https://lore.kernel.org/r/20200701194259.3337652-4-saravanak@google.com Signed-off-by: Greg Kroah-Hartman --- drivers/base/core.c | 21 +++++++++++++++++++++ include/linux/device.h | 3 ++- 2 files changed, 23 insertions(+), 1 deletion(-) diff --git a/drivers/base/core.c b/drivers/base/core.c index d1d2cdc3a8d89..05d414e9e8a40 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -50,6 +50,7 @@ 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 LIST_HEAD(deferred_fw_devlink); static DEFINE_MUTEX(defer_fw_devlink_lock); static bool fw_devlink_is_permissive(void); @@ -1244,6 +1245,12 @@ static void fw_devlink_link_device(struct device *dev) fw_ret = -EAGAIN; } else { fw_ret = -ENODEV; + /* + * defer_hook is not used to add device to deferred_sync list + * until device is bound. Since deferred fw devlink also blocks + * probing, same list hook can be used for deferred_fw_devlink. + */ + list_add_tail(&dev->links.defer_hook, &deferred_fw_devlink); } if (fw_ret == -ENODEV) @@ -1312,6 +1319,9 @@ void fw_devlink_pause(void) */ void fw_devlink_resume(void) { + struct device *dev, *tmp; + LIST_HEAD(probe_list); + mutex_lock(&defer_fw_devlink_lock); if (!defer_fw_devlink_count) { WARN(true, "Unmatched fw_devlink pause/resume!"); @@ -1323,8 +1333,19 @@ void fw_devlink_resume(void) goto out; device_link_add_missing_supplier_links(); + list_splice_tail_init(&deferred_fw_devlink, &probe_list); out: mutex_unlock(&defer_fw_devlink_lock); + + /* + * bus_probe_device() can cause new devices to get added and they'll + * try to grab defer_fw_devlink_lock. So, this needs to be done outside + * the defer_fw_devlink_lock. + */ + list_for_each_entry_safe(dev, tmp, &probe_list, links.defer_hook) { + list_del_init(&dev->links.defer_hook); + bus_probe_device(dev); + } } /* Device links support end. */ diff --git a/include/linux/device.h b/include/linux/device.h index 9bb2bc7bb8e33..5efed864b3871 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -433,7 +433,8 @@ enum dl_dev_state { * @suppliers: List of links to supplier devices. * @consumers: List of links to consumer devices. * @needs_suppliers: Hook to global list of devices waiting for suppliers. - * @defer_hook: Hook to global list of devices that have deferred sync_state. + * @defer_hook: Hook to global list of devices that have deferred sync_state or + * deferred fw_devlink. * @need_for_probe: If needs_suppliers is on a list, this indicates if the * suppliers are needed for probe or not. * @status: Driver status information.