• Michael Ellerman's avatar
    ata: pata_macio: Fix max_segment_size with PAGE_SIZE == 64K · 09fe2bfa
    Michael Ellerman authored
    The pata_macio driver advertises a max_segment_size of 0xff00, because
    the hardware doesn't cope with requests >= 64K.
    
    However the SCSI core requires max_segment_size to be at least
    PAGE_SIZE, which is a problem for pata_macio when the kernel is built
    with 64K pages.
    
    In older kernels the SCSI core would just increase the segment size to
    be equal to PAGE_SIZE, however since the commit tagged below it causes a
    warning and the device fails to probe:
    
      WARNING: CPU: 0 PID: 26 at block/blk-settings.c:202 .blk_validate_limits+0x2f8/0x35c
      CPU: 0 PID: 26 Comm: kworker/u4:1 Not tainted 6.10.0-rc1 #1
      Hardware name: PowerMac7,2 PPC970 0x390202 PowerMac
      ...
      NIP .blk_validate_limits+0x2f8/0x35c
      LR  .blk_alloc_queue+0xc0/0x2f8
      Call Trace:
        .blk_alloc_queue+0xc0/0x2f8
        .blk_mq_alloc_queue+0x60/0xf8
        .scsi_alloc_sdev+0x208/0x3c0
        .scsi_probe_and_add_lun+0x314/0x52c
        .__scsi_add_device+0x170/0x1a4
        .ata_scsi_scan_host+0x2bc/0x3e4
        .async_port_probe+0x6c/0xa0
        .async_run_entry_fn+0x60/0x1bc
        .process_one_work+0x228/0x510
        .worker_thread+0x360/0x530
        .kthread+0x134/0x13c
        .start_kernel_thread+0x10/0x14
      ...
      scsi_alloc_sdev: Allocation failure during SCSI scanning, some SCSI devices might not be configured
    
    Although the hardware can't cope with a 64K segment, the driver
    already deals with that internally by splitting large requests in
    pata_macio_qc_prep(). That is how the driver has managed to function
    until now on 64K kernels.
    
    So fix the driver to advertise a max_segment_size of 64K, which avoids
    the warning and keeps the SCSI core happy.
    
    Fixes: afd53a3d ("scsi: core: Initialize scsi midlayer limits before allocating the queue")
    Reported-by: default avatarGuenter Roeck <linux@roeck-us.net>
    Closes: https://lore.kernel.org/all/ce2bf6af-4382-4fe1-b392-cc6829f5ceb2@roeck-us.net/Reported-by: default avatarDoru Iorgulescu <doru.iorgulescu1@gmail.com>
    Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218858Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
    Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
    Reviewed-by: default avatarDamien Le Moal <dlemoal@kernel.org>
    Reviewed-by: default avatarJohn Garry <john.g.garry@oracle.com>
    Signed-off-by: default avatarNiklas Cassel <cassel@kernel.org>
    09fe2bfa
pata_macio.c 40 KB