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Commit fe304143 authored by Takashi Iwai's avatar Takashi Iwai Committed by Greg Kroah-Hartman
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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: default avatarTakashi Iwai <tiwai@suse.de>
Acked-by: default avatarMing Lei <ming.lei@canonical.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent d05c39ea

drivers/base/firmware_class.c

+37 −7
Original line number Diff line number Diff line
@@ -27,6 +27,7 @@ 
#include <linux/pm.h>

#include <linux/suspend.h>

#include <linux/syscore_ops.h>

#include <linux/reboot.h>



#include <generated/utsrelease.h>
@@ -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 +451,9 @@ 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;



	list_del_init(&buf->pending_list);

	set_bit(FW_STATUS_ABORT, &buf->status);

	complete_all(&buf->completion);

}
@@ -457,6 +461,25 @@ 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)
@@ -604,6 +627,7 @@ 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;

		}
@@ -612,7 +636,7 @@ static ssize_t firmware_loading_store(struct device *dev, 
		dev_err(dev, "%s: unexpected value (%d)\n", __func__, loading);

		/* fallthrough */

	case -1:

		fw_load_abort(fw_priv);

		fw_load_abort(fw_buf);

		break;

	}

out:
@@ -680,7 +704,7 @@ static int fw_realloc_buffer(struct firmware_priv *fw_priv, int min_size) 
		new_pages = kmalloc(new_array_size * sizeof(void *),

				    GFP_KERNEL);

		if (!new_pages) {

			fw_load_abort(fw_priv);

			fw_load_abort(buf);

			return -ENOMEM;

		}

		memcpy(new_pages, buf->pages,
@@ -697,7 +721,7 @@ static int fw_realloc_buffer(struct firmware_priv *fw_priv, int min_size) 
			alloc_page(GFP_KERNEL | __GFP_HIGHMEM);



		if (!buf->pages[buf->nr_pages]) {

			fw_load_abort(fw_priv);

			fw_load_abort(buf);

			return -ENOMEM;

		}

		buf->nr_pages++;
@@ -781,7 +805,7 @@ static void firmware_class_timeout_work(struct work_struct *work) 
		mutex_unlock(&fw_lock);

		return;

	}

	fw_load_abort(fw_priv);

	fw_load_abort(fw_priv->buf);

	mutex_unlock(&fw_lock);

}
@@ -857,6 +881,10 @@ 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);
@@ -1517,6 +1545,7 @@ 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;
@@ -1530,6 +1559,7 @@ 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

}