From 09fe2bfa6b83f865126ce3964744863f69a4a030 Mon Sep 17 00:00:00 2001 From: Michael Ellerman Date: Thu, 6 Jun 2024 21:14:45 +1000 Subject: [PATCH] ata: pata_macio: Fix max_segment_size with PAGE_SIZE == 64K 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: afd53a3d8528 ("scsi: core: Initialize scsi midlayer limits before allocating the queue") Reported-by: Guenter Roeck Closes: https://lore.kernel.org/all/ce2bf6af-4382-4fe1-b392-cc6829f5ceb2@roeck-us.net/ Reported-by: Doru Iorgulescu Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218858 Signed-off-by: Michael Ellerman Reviewed-by: Christoph Hellwig Reviewed-by: Damien Le Moal Reviewed-by: John Garry Signed-off-by: Niklas Cassel --- drivers/ata/pata_macio.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/drivers/ata/pata_macio.c b/drivers/ata/pata_macio.c index 817838e2f70e..3cb455a32d92 100644 --- a/drivers/ata/pata_macio.c +++ b/drivers/ata/pata_macio.c @@ -915,10 +915,13 @@ static const struct scsi_host_template pata_macio_sht = { .sg_tablesize = MAX_DCMDS, /* We may not need that strict one */ .dma_boundary = ATA_DMA_BOUNDARY, - /* Not sure what the real max is but we know it's less than 64K, let's - * use 64K minus 256 + /* + * The SCSI core requires the segment size to cover at least a page, so + * for 64K page size kernels this must be at least 64K. However the + * hardware can't handle 64K, so pata_macio_qc_prep() will split large + * requests. */ - .max_segment_size = MAX_DBDMA_SEG, + .max_segment_size = SZ_64K, .device_configure = pata_macio_device_configure, .sdev_groups = ata_common_sdev_groups, .can_queue = ATA_DEF_QUEUE,