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DMA transfers are not allowed to buffers that are on the stack. Therefore allocate a buffer to store the result of usb_control_message(). Fixes these bugreports: https://bugzilla.kernel.org/show_bug.cgi?id=195217 https://bugzilla.redhat.com/show_bug.cgi?id=1421387 https://bugzilla.redhat.com/show_bug.cgi?id=1427398 Shortened kernel backtrace from 4.11.9-200.fc25.x86_64: kernel: ------------[ cut here ]------------ kernel: WARNING: CPU: 3 PID: 2957 at drivers/usb/core/hcd.c:1587 kernel: transfer buffer not dma capable kernel: Call Trace: kernel: dump_stack+0x63/0x86 kernel: __warn+0xcb/0xf0 kernel: warn_slowpath_fmt+0x5a/0x80 kernel: usb_hcd_map_urb_for_dma+0x37f/0x570 kernel: ? try_to_del_timer_sync+0x53/0x80 kernel: usb_hcd_submit_urb+0x34e/0xb90 kernel: ? schedule_timeout+0x17e/0x300 kernel: ? del_timer_sync+0x50/0x50 kernel: ? __slab_free+0xa9/0x300 kernel: usb_submit_urb+0x2f4/0x560 kernel: ? urb_destroy+0x24/0x30 kernel: usb_start_wait_urb+0x6e/0x170 kernel: usb_control_msg+0xdc/0x120 kernel: mcs_get_reg+0x36/0x40 [mcs7780] kernel: mcs_net_open+0xb5/0x5c0 [mcs7780] ... Regression goes back to 4.9, so it's a good candidate for -stable. Though it's the decision of the maintainer. Thanks to Dan Williams for adding the "transfer buffer not dma capable" warning in the first place. It instantly pointed me in the right direction. Patch has been tested with transferring data from a Polar watch. Signed-off-by: Thomas Jarosch <thomas.jarosch@intra2net.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.