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Date: Wed, 22 May 2013 18:28:38 +0200
From: Takashi Iwai <tiwai@...e.de>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Ming Lei <ming.lei@...onical.com>, linux-kernel@...r.kernel.org
Subject: [PATCH v2 2/2] 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 <tiwai@...e.de>
---
v1->v2:
- get rid of enable flag check
- use an individual list for avoid link corruption
drivers/base/firmware_class.c | 44 ++++++++++++++++++++++++++++++++++++-------
1 file changed, 37 insertions(+), 7 deletions(-)
diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
index 4b1f926..e650c25 100644
--- a/drivers/base/firmware_class.c
+++ b/drivers/base/firmware_class.c
@@ -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
}
--
1.8.2.3
--
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