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由 Guenter Roeck 提交于
The latest kernel fails to boot qemu arm images when using scsi for disk access. Boot gets stuck after the following messages. brd: module loaded sym53c8xx 0000:00:0c.0: enabling device (0100 -> 0103) sym0: <895a> rev 0x0 at pci 0000:00:0c.0 irq 93 sym0: No NVRAM, ID 7, Fast-40, LVD, parity checking sym0: SCSI BUS has been reset. scsi host0: sym-2.2.3 Bisect points to commit 71e75c97 ("scsi: convert device_busy to atomic_t"). Code inspection shows the following suspicious change in scsi_request_fn. out_delay: - if (sdev->device_busy == 0 && !scsi_device_blocked(sdev)) + if (atomic_read(&sdev->device_busy) && !scsi_device_blocked(sdev)) blk_delay_queue(q, SCSI_QUEUE_DELAY); } 'sdev->device_busy == 0' was replaced with 'atomic_read(&sdev->device_busy)', meaning the logic was reversed. Changing this expression to '!atomic_read(&sdev->device_busy)' fixes the problem. Signed-off-by: NGuenter Roeck <linux@roeck-us.net> Reviewed-by: NHannes Reinecke <hare@suse.de> Acked-by: NJens Axboe <axboe@fb.com> Reviewed-by: NVenkatesh Srinivas <venkateshs@google.com> Reviewed-by: NWebb Scales <webbnh@hp.com> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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