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  1. Bug #387161
  2. Comment #21

Comment 21 for bug 387161

Revision history for this message
Martin Pitt (pitti) wrote : Re: External SATA->USB Drive gives lots of USB resets on ATA smart probing

devkit-disks-probe-ata-smart just calls sk_disk_open() and sk_disk_smart_is_available(), so something in those will most probably trigger the problem. It's not clear to me yet whether libatasmart does an invalid operation, or whether a valid operation triggers a kernel bug, so I keep both tasks open for now. The weird thing is that the calls actually succeed and it detects the SMART capability just fine.

sk_disk_smart_is_available() just checks a bit in a struct, and does not actually do any calls. All the magic is done by sk_disk_open(). What would be required now is someone going through devkit-disks-probe-ata-smart and sk_disk_open() with gdb singlestepping and find out which particular call/ioctl causes the USB resets.

What by and large happens is:

  - readonly open() of the device
  - fstat() and checks if it's a block device
  - BLKGETSIZE64 ioctl
  - some calls to libudev to get vendor, product, and bus type properties from sysfs
  - some SK_ATA_COMMAND_IDENTIFY_DEVICE ATA commands
  - call SK_SMART_COMMAND_ENABLE_OPERATIONS to enable smart if available

Anyone on this bug who understands gdb and can reproduce the problem?