From ffbe08a8e86d03513dc45b5389fab7f3477433b6 Mon Sep 17 00:00:00 2001 From: Saravana Kannan Date: Fri, 3 Mar 2023 16:53:53 -0800 Subject: [PATCH] driver core: Add fw_devlink.sync_state command line param When all devices that could probe have finished probing (based on deferred_probe_timeout configuration or late_initcall() when !CONFIG_MODULES), this parameter controls what to do with devices that haven't yet received their sync_state() calls. fw_devlink.sync_state=strict is the default and the driver core will continue waiting on all consumers of a device to probe successfully before sync_state() is called for the device. This is the default behavior since calling sync_state() on a device when all its consumers haven't probed could make some systems unusable/unstable. When this option is selected, we also print the list of devices that haven't had sync_state() called on them by the time all devices the could probe have finished probing. fw_devlink.sync_state=timeout will cause the driver core to give up waiting on consumers and call sync_state() on any devices that haven't yet received their sync_state() calls. This option is provided for systems that won't become unusable/unstable as they might be able to save power (depends on state of hardware before kernel starts) if all devices get their sync_state(). Signed-off-by: Saravana Kannan Link: https://lore.kernel.org/r/20230304005355.746421-2-saravanak@google.com Signed-off-by: Greg Kroah-Hartman --- Documentation/admin-guide/kernel-parameters.txt | 14 ++++++ drivers/base/base.h | 1 + drivers/base/core.c | 58 +++++++++++++++++++++++++ drivers/base/dd.c | 6 +++ 4 files changed, 79 insertions(+) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 207ca1d..76d8fdf 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -1582,6 +1582,20 @@ dependencies. This only applies for fw_devlink=on|rpm. Format: + fw_devlink.sync_state = + [KNL] When all devices that could probe have finished + probing, this parameter controls what to do with + devices that haven't yet received their sync_state() + calls. + Format: { strict | timeout } + strict -- Default. Continue waiting on consumers to + probe successfully. + timeout -- Give up waiting on consumers and call + sync_state() on any devices that haven't yet + received their sync_state() calls after + deferred_probe_timeout has expired or by + late_initcall() if !CONFIG_MODULES. + gamecon.map[2|3]= [HW,JOY] Multisystem joystick and NES/SNES/PSX pad support via parallel port (up to 5 devices per port) diff --git a/drivers/base/base.h b/drivers/base/base.h index 726a12a..6fcd718 100644 --- a/drivers/base/base.h +++ b/drivers/base/base.h @@ -209,6 +209,7 @@ extern void device_links_no_driver(struct device *dev); extern bool device_links_busy(struct device *dev); extern void device_links_unbind_consumers(struct device *dev); extern void fw_devlink_drivers_done(void); +extern void fw_devlink_probing_done(void); /* device pm support */ void device_pm_move_to_tail(struct device *dev); diff --git a/drivers/base/core.c b/drivers/base/core.c index ba11b51..871e651 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -1672,6 +1672,26 @@ static int __init fw_devlink_strict_setup(char *arg) } early_param("fw_devlink.strict", fw_devlink_strict_setup); +#define FW_DEVLINK_SYNC_STATE_STRICT 0 +#define FW_DEVLINK_SYNC_STATE_TIMEOUT 1 + +static int fw_devlink_sync_state; +static int __init fw_devlink_sync_state_setup(char *arg) +{ + if (!arg) + return -EINVAL; + + if (strcmp(arg, "strict") == 0) { + fw_devlink_sync_state = FW_DEVLINK_SYNC_STATE_STRICT; + return 0; + } else if (strcmp(arg, "timeout") == 0) { + fw_devlink_sync_state = FW_DEVLINK_SYNC_STATE_TIMEOUT; + return 0; + } + return -EINVAL; +} +early_param("fw_devlink.sync_state", fw_devlink_sync_state_setup); + static inline u32 fw_devlink_get_flags(u8 fwlink_flags) { if (fwlink_flags & FWLINK_FLAG_CYCLE) @@ -1742,6 +1762,44 @@ void fw_devlink_drivers_done(void) device_links_write_unlock(); } +static int fw_devlink_dev_sync_state(struct device *dev, void *data) +{ + struct device_link *link = to_devlink(dev); + struct device *sup = link->supplier; + + if (!(link->flags & DL_FLAG_MANAGED) || + link->status == DL_STATE_ACTIVE || sup->state_synced || + !dev_has_sync_state(sup)) + return 0; + + if (fw_devlink_sync_state == FW_DEVLINK_SYNC_STATE_STRICT) { + dev_warn(sup, "sync_state() pending due to %s\n", + dev_name(link->consumer)); + return 0; + } + + if (!list_empty(&sup->links.defer_sync)) + return 0; + + dev_warn(sup, "Timed out. Forcing sync_state()\n"); + sup->state_synced = true; + get_device(sup); + list_add_tail(&sup->links.defer_sync, data); + + return 0; +} + +void fw_devlink_probing_done(void) +{ + LIST_HEAD(sync_list); + + device_links_write_lock(); + class_for_each_device(&devlink_class, NULL, &sync_list, + fw_devlink_dev_sync_state); + device_links_write_unlock(); + device_links_flush_sync_list(&sync_list, NULL); +} + /** * wait_for_init_devices_probe - Try to probe any device needed for init * diff --git a/drivers/base/dd.c b/drivers/base/dd.c index 8def2ba..84f07e0 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -315,6 +315,8 @@ static void deferred_probe_timeout_work_func(struct work_struct *work) list_for_each_entry(p, &deferred_probe_pending_list, deferred_probe) dev_info(p->device, "deferred probe pending\n"); mutex_unlock(&deferred_probe_mutex); + + fw_devlink_probing_done(); } static DECLARE_DELAYED_WORK(deferred_probe_timeout_work, deferred_probe_timeout_work_func); @@ -364,6 +366,10 @@ static int deferred_probe_initcall(void) schedule_delayed_work(&deferred_probe_timeout_work, driver_deferred_probe_timeout * HZ); } + + if (!IS_ENABLED(CONFIG_MODULES)) + fw_devlink_probing_done(); + return 0; } late_initcall(deferred_probe_initcall); -- 2.7.4