[PATCH] hid: hid-led: fix issue with transfer buffer not being dma capable

[Heiner Kallweit <hkallweit1@gmail.com>]

The hid-led driver works fine under 4.8.0, however with the next
kernel from today I get this:

------------[ cut here ]------------
WARNING: CPU: 0 PID: 2578 at drivers/usb/core/hcd.c:1584 usb_hcd_map_urb_for_dma+0x373/0x550 [usbcore]
transfer buffer not dma capable
Modules linked in: hid_led(+) usbhid vfat fat ir_sony_decoder iwlmvm led_class mac80211 snd_hda_codec_realtek snd_hda_codec_generic x86_pkg_temp_thermal iwlwifi crc32c_intel snd_hda_codec_hdmi i2c_i801 i2c_smbus snd_hda_intel cfg80211 snd_hda_codec snd_hda_core snd_pcm r8169 snd_timer mei_me mii snd mei ir_lirc_codec lirc_dev nuvoton_cir rc_core btusb btintel bluetooth rfkill usb_storage efivarfs ipv6 ehci_pci ehci_hcd xhci_pci xhci_hcd usbcore usb_common ext4 jbd2 mbcache ahci libahci libata
CPU: 0 PID: 2578 Comm: systemd-udevd Not tainted 4.8.0-rc8-next-20161003 #1
Hardware name: ZOTAC ZBOX-CI321NANO/ZBOX-CI321NANO, BIOS B246P105 06/01/2015
 ffffc90003dbb7e0 ffffffff81280425 ffffc90003dbb830 0000000000000000
 ffffc90003dbb820 ffffffff8105b086 0000063003dbb800 ffff88006f374480
 0000000000000000 0000000000000000 0000000000000001 ffff880079544000
Call Trace:
 [<ffffffff81280425>] dump_stack+0x68/0x93
 [<ffffffff8105b086>] __warn+0xc6/0xe0
 [<ffffffff8105b0ea>] warn_slowpath_fmt+0x4a/0x50
 [<ffffffffa0143a43>] usb_hcd_map_urb_for_dma+0x373/0x550 [usbcore]
 [<ffffffffa01441b6>] usb_hcd_submit_urb+0x316/0x9c0 [usbcore]
 [<ffffffff810bce80>] ? rcu_read_lock_sched_held+0x40/0x80
 [<ffffffff810e0043>] ? module_assert_mutex_or_preempt+0x13/0x50
 [<ffffffff810e0c07>] ? __module_address+0x27/0xf0
 [<ffffffffa01456e4>] usb_submit_urb+0x2c4/0x520 [usbcore]
 [<ffffffffa0145fea>] usb_start_wait_urb+0x5a/0xe0 [usbcore]
 [<ffffffffa014612c>] usb_control_msg+0xbc/0xf0 [usbcore]
 [<ffffffff810e0c07>] ? __module_address+0x27/0xf0
 [<ffffffffa079a724>] usbhid_raw_request+0xa4/0x180 [usbhid]
 [<ffffffffa07a93b1>] hidled_recv+0x71/0xe0 [hid_led]
 [<ffffffffa07a947d>] thingm_init+0x2d/0x50 [hid_led]
 [<ffffffffa07a969b>] hidled_probe+0xcb/0x24a [hid_led]
 [<ffffffff814d96f2>] hid_device_probe+0xd2/0x150
 [<ffffffff8146023d>] driver_probe_device+0x1fd/0x2c0
 [<ffffffff8146039a>] __driver_attach+0x9a/0xa0
 [<ffffffff81460300>] ? driver_probe_device+0x2c0/0x2c0
 [<ffffffff8145e25d>] bus_for_each_dev+0x5d/0x90
 [<ffffffff8145fa79>] driver_attach+0x19/0x20
 [<ffffffff8145f5ff>] bus_add_driver+0x11f/0x220
 [<ffffffffa07ac000>] ? 0xffffffffa07ac000
 [<ffffffff8146086b>] driver_register+0x5b/0xd0
 [<ffffffffa07ac000>] ? 0xffffffffa07ac000
 [<ffffffff814d83d1>] __hid_register_driver+0x61/0xa0
 [<ffffffffa07ac01e>] hidled_driver_init+0x1e/0x20 [hid_led]
 [<ffffffff81000408>] do_one_initcall+0x38/0x150
 [<ffffffff810bce80>] ? rcu_read_lock_sched_held+0x40/0x80
 [<ffffffff81194ca0>] ? kmem_cache_alloc_trace+0x1d0/0x230
 [<ffffffff811342f9>] do_init_module+0x5a/0x1cb
 [<ffffffff810e3862>] load_module+0x1e42/0x2530
 [<ffffffff810e0990>] ? __symbol_put+0x50/0x50
 [<ffffffff810dfc50>] ? show_coresize+0x30/0x30
 [<ffffffff811ad650>] ? kernel_read_file+0x100/0x190
 [<ffffffff811ad794>] ? kernel_read_file_from_fd+0x44/0x70
 [<ffffffff810e415a>] SYSC_finit_module+0xba/0xc0
 [<ffffffff810e4179>] SyS_finit_module+0x9/0x10
 [<ffffffff815e082a>] entry_SYSCALL_64_fastpath+0x18/0xad
---[ end trace c9e6ea27003ecf9e ]---

Fix this by using a kmalloc'ed buffer when calling hid_hw_raw_request.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
---
 drivers/hid/hid-led.c | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/drivers/hid/hid-led.c b/drivers/hid/hid-led.c
index d8d55f3..6c2b8e0 100644
--- a/drivers/hid/hid-led.c
+++ b/drivers/hid/hid-led.c
@@ -67,6 +67,8 @@ union delcom_packet {
 #define DELCOM_RED_LED		1
 #define DELCOM_BLUE_LED		2
 
+#define MAX_REPORT_SIZE		16
+
 struct hidled_device;
 struct hidled_rgb;
 
@@ -100,11 +102,10 @@ struct hidled_device {
 	const struct hidled_config *config;
 	struct hid_device       *hdev;
 	struct hidled_rgb	*rgb;
+	u8			buf[MAX_REPORT_SIZE];
 	struct mutex		lock;
 };
 
-#define MAX_REPORT_SIZE		16
-
 #define to_hidled_led(arg) container_of(arg, struct hidled_led, cdev)
 
 static bool riso_kagaku_switch_green_blue;
@@ -118,13 +119,16 @@ static int hidled_send(struct hidled_device *ldev, __u8 *buf)
 
 	mutex_lock(&ldev->lock);
 
+	/* buffer provided to hid_hw_raw_request must not be on the stack */
+	memcpy(ldev->buf, buf, ldev->config->report_size);
+
 	if (ldev->config->report_type == RAW_REQUEST)
-		ret = hid_hw_raw_request(ldev->hdev, buf[0], buf,
+		ret = hid_hw_raw_request(ldev->hdev, buf[0], ldev->buf,
 					 ldev->config->report_size,
 					 HID_FEATURE_REPORT,
 					 HID_REQ_SET_REPORT);
 	else if (ldev->config->report_type == OUTPUT_REPORT)
-		ret = hid_hw_output_report(ldev->hdev, buf,
+		ret = hid_hw_output_report(ldev->hdev, ldev->buf,
 					   ldev->config->report_size);
 	else
 		ret = -EINVAL;
@@ -147,17 +151,21 @@ static int hidled_recv(struct hidled_device *ldev, __u8 *buf)
 
 	mutex_lock(&ldev->lock);
 
-	ret = hid_hw_raw_request(ldev->hdev, buf[0], buf,
+	memcpy(ldev->buf, buf, ldev->config->report_size);
+
+	ret = hid_hw_raw_request(ldev->hdev, buf[0], ldev->buf,
 				 ldev->config->report_size,
 				 HID_FEATURE_REPORT,
 				 HID_REQ_SET_REPORT);
 	if (ret < 0)
 		goto err;
 
-	ret = hid_hw_raw_request(ldev->hdev, buf[0], buf,
+	ret = hid_hw_raw_request(ldev->hdev, buf[0], ldev->buf,
 				 ldev->config->report_size,
 				 HID_FEATURE_REPORT,
 				 HID_REQ_GET_REPORT);
+
+	memcpy(buf, ldev->buf, ldev->config->report_size);
 err:
 	mutex_unlock(&ldev->lock);
 
-- 
2.10.0