Re: [PATCH] hid: hid-led: fix issue with transfer buffer not being dma capable
From: Alan Stern <hidden>
Date: 2016-10-03 18:22:38
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]
...
quoted hunk
Fix this by using a kmalloc'ed buffer when calling hid_hw_raw_request. Signed-off-by: Heiner Kallweit <redacted> --- 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 -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html