0ef9919a06
commit 176ddd89171ddcf661862d90c5d257877f7326d6 upstream. When the cache_type for the SCSI device is changed, the SCSI layer issues a MODE_SELECT command. The caching mode details are communicated via a request buffer associated with the SCSI command with data direction set as DMA_TO_DEVICE (scsi_mode_select()). When this command reaches the libata layer, as a part of generic initial setup, libata layer sets up the scatterlist for the command using the SCSI command (ata_scsi_qc_new()). This command is then translated by the libata layer into ATA_CMD_SET_FEATURES (ata_scsi_mode_select_xlat()). The libata layer treats this as a non-data command (ata_mselect_caching()), since it only needs an ATA taskfile to pass the caching on/off information to the device. It does not need the scatterlist that has been setup, so it does not perform dma_map_sg() on the scatterlist (ata_qc_issue()). Unfortunately, when this command reaches the libsas layer (sas_ata_qc_issue()), libsas layer sees it as a non-data command with a scatterlist. It cannot extract the correct DMA length since the scatterlist has not been mapped with dma_map_sg() for a DMA operation. When this partially constructed SAS task reaches pm80xx LLDD, it results in the following warning: "pm80xx_chip_sata_req 6058: The sg list address start_addr=0x0000000000000000 data_len=0x0end_addr_high=0xffffffff end_addr_low=0xffffffff has crossed 4G boundary" Update libsas to handle ATA non-data commands separately so num_scatter and total_xfer_len remain 0. Link: https://lore.kernel.org/r/20210318225632.2481291-1-jollys@google.com Fixes: 53de092f47ff ("scsi: libsas: Set data_dir as DMA_NONE if libata marks qc as NODATA") Tested-by: Luo Jiaxing <luojiaxing@huawei.com> Reviewed-by: John Garry <john.garry@huawei.com> Signed-off-by: Jolly Shah <jollys@google.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
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.