From 28cb7116eebfa0e4b36b154df0f1c6a251f3b97b Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Wed, 22 May 2013 18:28:38 +0200 Subject: [PATCH] firmware: Avoid deadlock of usermodehelper lock at shutdown When a system goes to reboot/shutdown, it tries to disable the usermode helper via usermodehelper_disable(). This might be blocked when a driver tries to load a firmware beforehand and it's stuck by some reason. For example, dell_rbu driver loads the firmware in non-hotplug mode and waits for user-space clearing the loading sysfs flag. If user-space doesn't clear the flag, it waits forever, thus blocks the reboot, too. As a workaround, in this patch, the firmware class driver registers a reboot notifier so that it can abort all pending f/w bufs before issuing usermodehelper_disable(). Signed-off-by: Takashi Iwai Acked-by: Ming Lei Signed-off-by: Greg Kroah-Hartman Conflicts: drivers/base/firmware_class.c Change-Id: I7ff6c198cd34090e55845b9d4035b1e5dc86226b --- drivers/base/firmware_class.c | 43 ++++++++++++++++++++++++++++++++--- 1 file changed, 40 insertions(+), 3 deletions(-) diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c index 01e21037d8fe..55d682e6ecea 100644 --- a/drivers/base/firmware_class.c +++ b/drivers/base/firmware_class.c @@ -27,6 +27,7 @@ #include #include #include +#include #include @@ -130,6 +131,7 @@ struct firmware_buf { struct page **pages; int nr_pages; int page_array_size; + struct list_head pending_list; #endif char fw_id[]; }; @@ -171,6 +173,9 @@ static struct firmware_buf *__allocate_fw_buf(const char *fw_name, strcpy(buf->fw_id, fw_name); buf->fwc = fwc; init_completion(&buf->completion); +#ifdef CONFIG_FW_LOADER_USER_HELPER + INIT_LIST_HEAD(&buf->pending_list); +#endif pr_debug("%s: fw-%s buf=%p\n", __func__, fw_name, buf); @@ -446,10 +451,8 @@ static struct firmware_priv *to_firmware_priv(struct device *dev) return container_of(dev, struct firmware_priv, dev); } -static void fw_load_abort(struct firmware_priv *fw_priv) +static void __fw_load_abort(struct firmware_buf *buf) { - struct firmware_buf *buf = fw_priv->buf; - /* * There is a small window in which user can write to 'loading' * between loading done and disappearance of 'loading' @@ -457,8 +460,16 @@ static void fw_load_abort(struct firmware_priv *fw_priv) if (test_bit(FW_STATUS_DONE, &buf->status)) return; + list_del_init(&buf->pending_list); set_bit(FW_STATUS_ABORT, &buf->status); complete_all(&buf->completion); +} + +static void fw_load_abort(struct firmware_priv *fw_priv) +{ + struct firmware_buf *buf = fw_priv->buf; + + __fw_load_abort(buf); /* avoid user action after loading abort */ fw_priv->buf = NULL; @@ -467,6 +478,25 @@ static void fw_load_abort(struct firmware_priv *fw_priv) #define is_fw_load_aborted(buf) \ test_bit(FW_STATUS_ABORT, &(buf)->status) +static LIST_HEAD(pending_fw_head); + +/* reboot notifier for avoid deadlock with usermode_lock */ +static int fw_shutdown_notify(struct notifier_block *unused1, + unsigned long unused2, void *unused3) +{ + mutex_lock(&fw_lock); + while (!list_empty(&pending_fw_head)) + __fw_load_abort(list_first_entry(&pending_fw_head, + struct firmware_buf, + pending_list)); + mutex_unlock(&fw_lock); + return NOTIFY_DONE; +} + +static struct notifier_block fw_shutdown_nb = { + .notifier_call = fw_shutdown_notify, +}; + static ssize_t firmware_timeout_show(struct class *class, struct class_attribute *attr, char *buf) @@ -619,6 +649,7 @@ static ssize_t firmware_loading_store(struct device *dev, * is completed. * */ fw_map_pages_buf(fw_buf); + list_del_init(&fw_buf->pending_list); complete_all(&fw_buf->completion); break; } @@ -868,6 +899,10 @@ static int _request_firmware_load(struct firmware_priv *fw_priv, bool uevent, kobject_uevent(&fw_priv->dev.kobj, KOBJ_ADD); } + mutex_lock(&fw_lock); + list_add(&buf->pending_list, &pending_fw_head); + mutex_unlock(&fw_lock); + wait_for_completion(&buf->completion); cancel_delayed_work_sync(&fw_priv->timeout_work); @@ -1526,6 +1561,7 @@ static int __init firmware_class_init(void) { fw_cache_init(); #ifdef CONFIG_FW_LOADER_USER_HELPER + register_reboot_notifier(&fw_shutdown_nb); return class_register(&firmware_class); #else return 0; @@ -1539,6 +1575,7 @@ static void __exit firmware_class_exit(void) unregister_pm_notifier(&fw_cache.pm_notify); #endif #ifdef CONFIG_FW_LOADER_USER_HELPER + unregister_reboot_notifier(&fw_shutdown_nb); class_unregister(&firmware_class); #endif } -- 2.34.1