[PATCH] firmware: Make user-mode helper optional

[Takashi Iwai]

Since 3.7 kernel, the firmware loader can read the firmware files
directly, and the traditional user-mode helper is invoked only as a
fallback.  This seems working pretty well, and the next step would be
to reduce the redundant user-mode helper stuff in future.

This patch is a preparation for that, to make the user-mode helper
invocation optional via kconfig.  Other than that, there is no
functional change here.

Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
---
 drivers/base/Kconfig          |  11 ++
 drivers/base/firmware_class.c | 350 +++++++++++++++++++++++++-----------------
 2 files changed, 218 insertions(+), 143 deletions(-)

diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig
index c8b4539..07abd9d 100644
--- a/drivers/base/Kconfig
+++ b/drivers/base/Kconfig
@@ -145,6 +145,17 @@ config EXTRA_FIRMWARE_DIR
 	  this option you can point it elsewhere, such as /lib/firmware/ or
 	  some other directory containing the firmware files.
 
+config FW_LOADER_USER_HELPER
+	bool "Fallback user-helper invocation for firmware loading"
+	depends on FW_LOADER
+	default y
+	help
+	  This option enables / disables the invocation of user-helper
+	  (e.g. udev) for loading firmware files as a fallback after the
+	  direct file loading in kernel fails.  The user-mode helper is
+	  no longer required unless you have a special firmware file that
+	  resides in a non-standard path.
+
 config DEBUG_DRIVER
 	bool "Driver Core verbose debug messages"
 	depends on DEBUG_KERNEL
diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
index b392b35..6c6f714 100644
--- a/drivers/base/firmware_class.c
+++ b/drivers/base/firmware_class.c
@@ -88,6 +88,7 @@ enum {
 	FW_STATUS_ABORT,
 };
 
+#ifdef CONFIG_FW_LOADER_USER_HELPER
 enum fw_buf_fmt {
 	VMALLOC_BUF,	/* used in direct loading */
 	PAGE_BUF,	/* used in loading via userspace */
@@ -99,6 +100,7 @@ static inline long firmware_loading_timeout(void)
 {
 	return loading_timeout > 0 ? loading_timeout * HZ : MAX_SCHEDULE_TIMEOUT;
 }
+#endif /* CONFIG_FW_LOADER_USER_HELPER */
 
 struct firmware_cache {
 	/* firmware_buf instance will be added into the below list */
@@ -128,12 +130,14 @@ struct firmware_buf {
 	struct completion completion;
 	struct firmware_cache *fwc;
 	unsigned long status;
-	enum fw_buf_fmt fmt;
 	void *data;
 	size_t size;
+#ifdef CONFIG_FW_LOADER_USER_HELPER
+	enum fw_buf_fmt fmt;
 	struct page **pages;
 	int nr_pages;
 	int page_array_size;
+#endif
 	char fw_id[];
 };
 
@@ -142,6 +146,7 @@ struct fw_cache_entry {
 	char name[];
 };
 
+#ifdef CONFIG_FW_LOADER_USER_HELPER
 struct firmware_priv {
 	struct delayed_work timeout_work;
 	bool nowait;
@@ -149,6 +154,7 @@ struct firmware_priv {
 	struct firmware_buf *buf;
 	struct firmware *fw;
 };
+#endif
 
 struct fw_name_devm {
 	unsigned long magic;
@@ -182,7 +188,9 @@ 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
 	buf->fmt = VMALLOC_BUF;
+#endif
 
 	pr_debug("%s: fw-%s buf=%p\n", __func__, fw_name, buf);
 
@@ -240,7 +248,6 @@ static void __fw_free_buf(struct kref *ref)
 {
 	struct firmware_buf *buf = to_fwbuf(ref);
 	struct firmware_cache *fwc = buf->fwc;
-	int i;
 
 	pr_debug("%s: fw-%s buf=%p data=%p size=%u\n",
 		 __func__, buf->fw_id, buf, buf->data,
@@ -250,12 +257,15 @@ static void __fw_free_buf(struct kref *ref)
 	spin_unlock(&fwc->lock);
 
 
+#ifdef CONFIG_FW_LOADER_USER_HELPER
 	if (buf->fmt == PAGE_BUF) {
+		int i;
 		vunmap(buf->data);
 		for (i = 0; i < buf->nr_pages; i++)
 			__free_page(buf->pages[i]);
 		kfree(buf->pages);
 	} else
+#endif
 		vfree(buf->data);
 	kfree(buf);
 }
@@ -319,7 +329,8 @@ static bool fw_read_file_contents(struct file *file, struct firmware_buf *fw_buf
 	return true;
 }
 
-static bool fw_get_filesystem_firmware(struct firmware_buf *buf)
+static bool fw_get_filesystem_firmware(struct device *device,
+				       struct firmware_buf *buf)
 {
 	int i;
 	bool success = false;
@@ -343,9 +354,32 @@ static bool fw_get_filesystem_firmware(struct firmware_buf *buf)
 			break;
 	}
 	__putname(path);
+
+	if (success) {
+		dev_dbg(device, "firmware: direct-loading firmware %s\n",
+			buf->fw_id);
+		mutex_lock(&fw_lock);
+		set_bit(FW_STATUS_DONE, &buf->status);
+		mutex_unlock(&fw_lock);
+		complete_all(&buf->completion);
+	}
+
 	return success;
 }
 
+/* firmware holds the ownership of pages */
+static void firmware_free_data(const struct firmware *fw)
+{
+	/* Loaded directly? */
+	if (!fw->priv) {
+		vfree(fw->data);
+		return;
+	}
+	fw_free_buf(fw->priv);
+}
+
+#ifdef CONFIG_FW_LOADER_USER_HELPER
+
 static struct firmware_priv *to_firmware_priv(struct device *dev)
 {
 	return container_of(dev, struct firmware_priv, dev);
@@ -435,17 +469,6 @@ static ssize_t firmware_loading_show(struct device *dev,
 	return sprintf(buf, "%d\n", loading);
 }
 
-/* firmware holds the ownership of pages */
-static void firmware_free_data(const struct firmware *fw)
-{
-	/* Loaded directly? */
-	if (!fw->priv) {
-		vfree(fw->data);
-		return;
-	}
-	fw_free_buf(fw->priv);
-}
-
 /* Some architectures don't have PAGE_KERNEL_RO */
 #ifndef PAGE_KERNEL_RO
 #define PAGE_KERNEL_RO PAGE_KERNEL
@@ -726,14 +749,17 @@ fw_create_instance(struct firmware *firmware, const char *fw_name,
 exit:
 	return fw_priv;
 }
+#endif /* CONFIG_FW_LOADER_USER_HELPER */
 
 /* store the pages buffer info firmware from buf */
 static void fw_set_page_data(struct firmware_buf *buf, struct firmware *fw)
 {
 	fw->priv = buf;
-	fw->pages = buf->pages;
 	fw->size = buf->size;
 	fw->data = buf->data;
+#ifdef CONFIG_FW_LOADER_USER_HELPER
+	fw->pages = buf->pages;
+#endif
 
 	pr_debug("%s: fw-%s buf=%p data=%p size=%u\n",
 		 __func__, buf->fw_id, buf, buf->data,
@@ -796,78 +822,113 @@ static int fw_add_devm_name(struct device *dev, const char *name)
 }
 #endif
 
-static void _request_firmware_cleanup(const struct firmware **firmware_p)
+static void _request_firmware_cleanup(struct firmware **firmware_p)
 {
 	release_firmware(*firmware_p);
 	*firmware_p = NULL;
 }
 
-static struct firmware_priv *
-_request_firmware_prepare(const struct firmware **firmware_p, const char *name,
-			  struct device *device, bool uevent, bool nowait)
+/* wait until the shared firmware_buf becomes ready (or error) */
+static int sync_cached_firmware_buf(struct firmware_buf *buf)
+{
+	int ret = 0;
+
+	mutex_lock(&fw_lock);
+	while (!test_bit(FW_STATUS_DONE, &buf->status)) {
+		if (test_bit(FW_STATUS_ABORT, &buf->status)) {
+			ret = -ENOENT;
+			break;
+		}
+		mutex_unlock(&fw_lock);
+		wait_for_completion(&buf->completion);
+		mutex_lock(&fw_lock);
+	}
+	mutex_unlock(&fw_lock);
+	return ret;
+}
+
+/* prepare firmware and firmware_buf structs;
+ * return 1 if a firmware is already assigned, 0 if need to load one,
+ * or a negative error code
+ */
+static int
+_request_firmware_prepare(struct firmware **firmware_p, const char *name,
+			  struct device *device)
 {
 	struct firmware *firmware;
-	struct firmware_priv *fw_priv = NULL;
 	struct firmware_buf *buf;
 	int ret;
 
-	if (!firmware_p)
-		return ERR_PTR(-EINVAL);
-
 	*firmware_p = firmware = kzalloc(sizeof(*firmware), GFP_KERNEL);
 	if (!firmware) {
 		dev_err(device, "%s: kmalloc(struct firmware) failed\n",
 			__func__);
-		return ERR_PTR(-ENOMEM);
+		return -ENOMEM;
 	}
 
 	if (fw_get_builtin_firmware(firmware, name)) {
 		dev_dbg(device, "firmware: using built-in firmware %s\n", name);
-		return NULL;
+		return 1; /* assigned */
 	}
 
 	ret = fw_lookup_and_allocate_buf(name, &fw_cache, &buf);
-	if (!ret)
-		fw_priv = fw_create_instance(firmware, name, device,
-				uevent, nowait);
 
-	if (IS_ERR(fw_priv) || ret < 0) {
-		kfree(firmware);
-		*firmware_p = NULL;
-		return ERR_PTR(-ENOMEM);
-	} else if (fw_priv) {
-		fw_priv->buf = buf;
+	/* bind buf with firmware so that it'll be released upon
+	 * request_firmware() call
+	 */
+	firmware->priv = buf;
 
-		/*
-		 * bind with 'buf' now to avoid warning in failure path
-		 * of requesting firmware.
-		 */
-		firmware->priv = buf;
-		return fw_priv;
+	if (ret > 0) {
+		ret = sync_cached_firmware_buf(buf);
+		if (!ret) {
+			fw_set_page_data(buf, firmware);
+			return 1; /* assigned */
+		}
 	}
 
-	/* share the cached buf, which is inprogessing or completed */
- check_status:
-	mutex_lock(&fw_lock);
-	if (test_bit(FW_STATUS_ABORT, &buf->status)) {
-		fw_priv = ERR_PTR(-ENOENT);
-		firmware->priv = buf;
+	if (ret < 0)
 		_request_firmware_cleanup(firmware_p);
-		goto exit;
-	} else if (test_bit(FW_STATUS_DONE, &buf->status)) {
-		fw_priv = NULL;
-		fw_set_page_data(buf, firmware);
-		goto exit;
+
+	return 0;
+}
+
+static int assign_firmware_buf(struct firmware *fw, struct device *device)
+{
+	struct firmware_buf *buf = fw->priv;
+
+	mutex_lock(&fw_lock);
+	if (!buf->size || test_bit(FW_STATUS_ABORT, &buf->status)) {
+		mutex_unlock(&fw_lock);
+		return -ENOENT;
 	}
-	mutex_unlock(&fw_lock);
-	wait_for_completion(&buf->completion);
-	goto check_status;
 
-exit:
+	/*
+	 * add firmware name into devres list so that we can auto cache
+	 * and uncache firmware for device.
+	 *
+	 * device may has been deleted already, but the problem
+	 * should be fixed in devres or driver core.
+	 */
+	if (device)
+		fw_add_devm_name(device, buf->fw_id);
+
+	/*
+	 * After caching firmware image is started, let it piggyback
+	 * on request firmware.
+	 */
+	if (buf->fwc->state == FW_LOADER_START_CACHE) {
+		if (fw_cache_piggyback_on_request(buf->fw_id))
+			kref_get(&buf->ref);
+	}
+
+	/* pass the pages buffer to driver at the last minute */
+	fw_set_page_data(buf, fw);
 	mutex_unlock(&fw_lock);
-	return fw_priv;
+	return 0;
 }
 
+#ifdef CONFIG_FW_LOADER_USER_HELPER
+/* load a firmware via user helper */
 static int _request_firmware_load(struct firmware_priv *fw_priv, bool uevent,
 				  long timeout)
 {
@@ -875,20 +936,6 @@ static int _request_firmware_load(struct firmware_priv *fw_priv, bool uevent,
 	struct device *f_dev = &fw_priv->dev;
 	struct firmware_buf *buf = fw_priv->buf;
 	struct firmware_cache *fwc = &fw_cache;
-	int direct_load = 0;
-
-	/* try direct loading from fs first */
-	if (fw_get_filesystem_firmware(buf)) {
-		dev_dbg(f_dev->parent, "firmware: direct-loading"
-			" firmware %s\n", buf->fw_id);
-
-		mutex_lock(&fw_lock);
-		set_bit(FW_STATUS_DONE, &buf->status);
-		mutex_unlock(&fw_lock);
-		complete_all(&buf->completion);
-		direct_load = 1;
-		goto handle_fw;
-	}
 
 	/* fall back on userspace loading */
 	buf->fmt = PAGE_BUF;
@@ -929,38 +976,10 @@ static int _request_firmware_load(struct firmware_priv *fw_priv, bool uevent,
 
 	cancel_delayed_work_sync(&fw_priv->timeout_work);
 
-handle_fw:
-	mutex_lock(&fw_lock);
-	if (!buf->size || test_bit(FW_STATUS_ABORT, &buf->status))
-		retval = -ENOENT;
-
-	/*
-	 * add firmware name into devres list so that we can auto cache
-	 * and uncache firmware for device.
-	 *
-	 * f_dev->parent may has been deleted already, but the problem
-	 * should be fixed in devres or driver core.
-	 */
-	if (!retval && f_dev->parent)
-		fw_add_devm_name(f_dev->parent, buf->fw_id);
-
-	/*
-	 * After caching firmware image is started, let it piggyback
-	 * on request firmware.
-	 */
-	if (!retval && fwc->state == FW_LOADER_START_CACHE) {
-		if (fw_cache_piggyback_on_request(buf->fw_id))
-			kref_get(&buf->ref);
-	}
-
-	/* pass the pages buffer to driver at the last minute */
-	fw_set_page_data(buf, fw_priv->fw);
+	if (!retval)
+		retval = assign_firmware_buf(fw_priv->fw, f_dev->parent);
 
 	fw_priv->buf = NULL;
-	mutex_unlock(&fw_lock);
-
-	if (direct_load)
-		goto err_put_dev;
 
 	device_remove_file(f_dev, &dev_attr_loading);
 err_del_bin_attr:
@@ -972,6 +991,78 @@ err_put_dev:
 	return retval;
 }
 
+static int fw_load_from_user_helper(struct firmware *firmware,
+				    const char *name, struct device *device,
+				    bool uevent, long timeout)
+{
+	struct firmware_priv *fw_priv;
+	long timeout;
+	int ret;
+
+	fw_priv = fw_create_instance(*firmware_p, name, device, uevent, timeout);
+	if (IS_ERR(fw_priv))
+		return PTR_ERR(fw_priv);
+
+	fw_priv->buf = firmware->priv;
+
+	timeout = firmware_loading_timeout();
+	if (nowait) {
+		timeout = usermodehelper_read_lock_wait(timeout);
+		if (!timeout) {
+			dev_dbg(device, "firmware: %s loading timed out\n",
+				name);
+			kfree(fw_priv);
+			return -EAGAIN;
+		}
+	} else {
+		ret = usermodehelper_read_trylock();
+		if (WARN_ON(ret)) {
+			dev_err(device, "firmware: %s will not be loaded\n",
+				name);
+			kfree(fw_priv);
+			return ret;
+		}
+	}
+
+	ret = _request_firmware_load(fw_priv, uevent, timeout);
+	usermodehelper_read_unlock();
+	return ret;
+}
+#else /* CONFIG_FW_LOADER_USER_HELPER */
+static inline int
+fw_load_from_user_helper(struct firmware *firmware, const char *name,
+			 struct device *device, bool uevent, long timeout)
+{
+	return -ENOENT;
+}
+#endif /* CONFIG_FW_LOADER_USER_HELPER */
+
+static int
+_request_firmware(const struct firmware **firmware_p, const char *name,
+		  struct device *device, bool uevent, bool nowait)
+{
+	struct firmware *fw;
+	int ret;
+
+	ret = _request_firmware_prepare(&fw, name, device);
+	if (ret < 0)
+		return ret;
+	else if (ret) { /* assigned from either built-in or cache */
+		*firmware_p = fw;
+		return 0;
+	}
+
+	if (fw_get_filesystem_firmware(device, fw->priv))
+		ret = assign_firmware_buf(fw, device);
+	else
+		ret = fw_load_from_user_helper(fw, name, device,
+					       uevent, nowait);
+	if (ret)
+		_request_firmware_cleanup(&fw);
+	*firmware_p = fw;
+	return ret;
+}
+
 /**
  * request_firmware: - send firmware request and wait for it
  * @firmware_p: pointer to firmware image
@@ -994,28 +1085,9 @@ err_put_dev:
  **/
 int
 request_firmware(const struct firmware **firmware_p, const char *name,
-                 struct device *device)
+		 struct device *device)
 {
-	struct firmware_priv *fw_priv;
-	int ret;
-
-	fw_priv = _request_firmware_prepare(firmware_p, name, device, true,
-					    false);
-	if (IS_ERR_OR_NULL(fw_priv))
-		return PTR_RET(fw_priv);
-
-	ret = usermodehelper_read_trylock();
-	if (WARN_ON(ret)) {
-		dev_err(device, "firmware: %s will not be loaded\n", name);
-	} else {
-		ret = _request_firmware_load(fw_priv, true,
-					firmware_loading_timeout());
-		usermodehelper_read_unlock();
-	}
-	if (ret)
-		_request_firmware_cleanup(firmware_p);
-
-	return ret;
+	return _request_firmware(firmware_p, name, device, true, false);
 }
 
 /**
@@ -1046,31 +1118,11 @@ static void request_firmware_work_func(struct work_struct *work)
 {
 	struct firmware_work *fw_work;
 	const struct firmware *fw;
-	struct firmware_priv *fw_priv;
-	long timeout;
-	int ret;
 
 	fw_work = container_of(work, struct firmware_work, work);
-	fw_priv = _request_firmware_prepare(&fw, fw_work->name, fw_work->device,
-			fw_work->uevent, true);
-	if (IS_ERR_OR_NULL(fw_priv)) {
-		ret = PTR_RET(fw_priv);
-		goto out;
-	}
-
-	timeout = usermodehelper_read_lock_wait(firmware_loading_timeout());
-	if (timeout) {
-		ret = _request_firmware_load(fw_priv, fw_work->uevent, timeout);
-		usermodehelper_read_unlock();
-	} else {
-		dev_dbg(fw_work->device, "firmware: %s loading timed out\n",
-			fw_work->name);
-		ret = -EAGAIN;
-	}
-	if (ret)
-		_request_firmware_cleanup(&fw);
 
- out:
+	_request_firmware(&fw, fw_work->name, fw_work->device,
+			  fw_work->uevent, true);
 	fw_work->cont(fw, fw_work->context);
 	put_device(fw_work->device);
 
@@ -1347,7 +1399,9 @@ static void __device_uncache_fw_images(void)
 static void device_cache_fw_images(void)
 {
 	struct firmware_cache *fwc = &fw_cache;
+#ifdef CONFIG_FW_LOADER_USER_HELPER
 	int old_timeout;
+#endif
 	DEFINE_WAIT(wait);
 
 	pr_debug("%s\n", __func__);
@@ -1355,6 +1409,7 @@ static void device_cache_fw_images(void)
 	/* cancel uncache work */
 	cancel_delayed_work_sync(&fwc->work);
 
+#ifdef CONFIG_FW_LOADER_USER_HELPER
 	/*
 	 * use small loading timeout for caching devices' firmware
 	 * because all these firmware images have been loaded
@@ -1365,6 +1420,7 @@ static void device_cache_fw_images(void)
 	 */
 	old_timeout = loading_timeout;
 	loading_timeout = 10;
+#endif
 
 	mutex_lock(&fw_lock);
 	fwc->state = FW_LOADER_START_CACHE;
@@ -1374,7 +1430,9 @@ static void device_cache_fw_images(void)
 	/* wait for completion of caching firmware for all devices */
 	async_synchronize_full_domain(&fw_cache_domain);
 
+#ifdef CONFIG_FW_LOADER_USER_HELPER
 	loading_timeout = old_timeout;
+#endif
 }
 
 /**
@@ -1474,7 +1532,11 @@ static void __init fw_cache_init(void)
 static int __init firmware_class_init(void)
 {
 	fw_cache_init();
+#ifdef CONFIG_FW_LOADER_USER_HELPER
 	return class_register(&firmware_class);
+#else
+	return 0;
+#endif
 }
 
 static void __exit firmware_class_exit(void)
@@ -1483,7 +1545,9 @@ static void __exit firmware_class_exit(void)
 	unregister_syscore_ops(&fw_syscore_ops);
 	unregister_pm_notifier(&fw_cache.pm_notify);
 #endif
+#ifdef CONFIG_FW_LOADER_USER_HELPER
 	class_unregister(&firmware_class);
+#endif
 }
 
 fs_initcall(firmware_class_init);
-- 
1.8.1.1

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