Commit d74ffae8 authored Jul 22, 2019 by Yoshihiro Shimoda Committed by Greg Kroah-Hartman Jul 25, 2019

usb-storage: Add a limitation for blk_queue_max_hw_sectors()



This patch fixes an issue that the following error happens on
swiotlb environment:

	xhci-hcd ee000000.usb: swiotlb buffer is full (sz: 524288 bytes), total 32768 (slots), used 1338 (slots)

On the kernel v5.1, block settings of a usb-storage with SuperSpeed
were the following so that the block layer will allocate buffers
up to 64 KiB, and then the issue didn't happen.

	max_segment_size = 65536
	max_hw_sectors_kb = 1024

After the commit 09324d32 ("block: force an unlimited segment
size on queues with a virt boundary") is applied, the block settings
are the following. So, the block layer will allocate buffers up to
1024 KiB, and then the issue happens:

	max_segment_size = 4294967295
	max_hw_sectors_kb = 1024

To fix the issue, the usb-storage driver checks the maximum size of
a mapping for the device and then adjusts the max_hw_sectors_kb
if required. After this patch is applied, the block settings will
be the following, and then the issue doesn't happen.

	max_segment_size = 4294967295
	max_hw_sectors_kb = 256

Fixes: 09324d32 ("block: force an unlimited segment size on queues with a virt boundary")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/1563793105-20597-1-git-send-email-yoshihiro.shimoda.uh@renesas.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 4fbb8aa7

drivers/usb/storage/scsiglue.c

+11 −0

Original line number	Diff line number	Diff line
		@@ -28,6 +28,8 @@
		* status of a command.
		*/

		#include <linux/blkdev.h>
		#include <linux/dma-mapping.h>
		#include <linux/module.h>
		#include <linux/mutex.h>

		@@ -99,6 +101,7 @@ static int slave_alloc (struct scsi_device *sdev)
		static int slave_configure(struct scsi_device *sdev)
		{
		struct us_data *us = host_to_us(sdev->host);
		struct device *dev = us->pusb_dev->bus->sysdev;

		/*
		* Many devices have trouble transferring more than 32KB at a time,
		@@ -128,6 +131,14 @@ static int slave_configure(struct scsi_device *sdev)
		blk_queue_max_hw_sectors(sdev->request_queue, 2048);
		}

		/*
		* The max_hw_sectors should be up to maximum size of a mapping for
		* the device. Otherwise, a DMA API might fail on swiotlb environment.
		*/
		blk_queue_max_hw_sectors(sdev->request_queue,
		min_t(size_t, queue_max_hw_sectors(sdev->request_queue),
		dma_max_mapping_size(dev) >> SECTOR_SHIFT));

		/*
		* Some USB host controllers can't do DMA; they have to use PIO.
		* They indicate this by setting their dma_mask to NULL. For

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