From: Alan Stern stern@rowland.harvard.edu
commit 9a976949613132977098fc49510b46fa8678d864 upstream.
Commit 747668dbc061 ("usb-storage: Set virt_boundary_mask to avoid SG overflows") attempted to solve a problem involving scatter-gather I/O and USB/IP by setting the virt_boundary_mask for mass-storage devices.
However, it now turns out that this interacts badly with commit 09324d32d2a0 ("block: force an unlimited segment size on queues with a virt boundary"), which was added later. A typical error message is:
ehci-pci 0000:00:13.2: swiotlb buffer is full (sz: 327680 bytes), total 32768 (slots), used 97 (slots)
There is no longer any reason to keep the virt_boundary_mask setting for usb-storage. It was needed in the first place only for handling devices with a block size smaller than the maxpacket size and where the host controller was not capable of fully general scatter-gather operation (that is, able to merge two SG segments into a single USB packet). But:
High-speed or slower connections never use a bulk maxpacket value larger than 512;
The SCSI layer does not handle block devices with a block size smaller than 512 bytes;
All the host controllers capable of SuperSpeed operation can handle fully general SG;
Since commit ea44d190764b ("usbip: Implement SG support to vhci-hcd and stub driver") was merged, the USB/IP driver can also handle SG.
Therefore all supported device/controller combinations should be okay with no need for any special virt_boundary_mask. So in order to fix the swiotlb problem, this patch reverts commit 747668dbc061.
Reported-and-tested-by: Piergiorgio Sartor piergiorgio.sartor@nexgo.de Link: https://marc.info/?l=linux-usb&m=157134199501202&w=2 Signed-off-by: Alan Stern stern@rowland.harvard.edu CC: Seth Bollinger Seth.Bollinger@digi.com CC: stable@vger.kernel.org Fixes: 747668dbc061 ("usb-storage: Set virt_boundary_mask to avoid SG overflows") Acked-by: Christoph Hellwig hch@lst.de Link: https://lore.kernel.org/r/Pine.LNX.4.44L0.1910211145520.1673-100000@iolanthe... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/usb/storage/scsiglue.c | 10 ---------- 1 file changed, 10 deletions(-)
--- a/drivers/usb/storage/scsiglue.c +++ b/drivers/usb/storage/scsiglue.c @@ -81,7 +81,6 @@ static const char* host_info(struct Scsi static int slave_alloc (struct scsi_device *sdev) { struct us_data *us = host_to_us(sdev->host); - int maxp;
/* * Set the INQUIRY transfer length to 36. We don't use any of @@ -91,15 +90,6 @@ static int slave_alloc (struct scsi_devi sdev->inquiry_len = 36;
/* - * USB has unusual scatter-gather requirements: the length of each - * scatterlist element except the last must be divisible by the - * Bulk maxpacket value. Fortunately this value is always a - * power of 2. Inform the block layer about this requirement. - */ - maxp = usb_maxpacket(us->pusb_dev, us->recv_bulk_pipe, 0); - blk_queue_virt_boundary(sdev->request_queue, maxp - 1); - - /* * Some host controllers may have alignment requirements. * We'll play it safe by requiring 512-byte alignment always. */