On Mon, 3 Oct 2016, Heiner Kallweit wrote:
> 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]
...
> Fix this by using a kmalloc'ed buffer when calling hid_hw_raw_request.
>
> Signed-off-by: Heiner Kallweit <hkallweit1@xxxxxxxxx>
> ---
> 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);
In fact, this is not the best way to solve the problem. Not only must
the buffer be dynamically allocated, it also must not be part of a
larger structure (such as struct hidled_device).
Instead you should change the routines that call hidled_recv and
hidled_send. Make each of them allocate a buffer using kmalloc rather
than use a buffer on the stack.
Alan Stern
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