Hi all,
I have a user space driver for a device and am using USBDEVFS_BULK
ioctl() calls to transfer data. My code works fine on an armv5b machine
with Linux 2.4.22-xfs ehci_hcd, however the same code hangs when
attempting to transfer larger chunks of data on a mipsel machine with
Linux 2.6.12-rc1 ehci_hcd
As you can see from the included application trace, sending and
receiving data of up to a few hundred bytes is OK, but a few kB at a
time hangs.
usb_bulk_write:ioctl - send 18 bytes
usbdevfs_bulktransfer: ep=0x01, len=18, timeout=1100, data=0x7fe79c80
usb_bulk_write:ioctl - sent 18 bytes
usb_bulk_read:ioctl - request 4096 bytes
usbdevfs_bulktransfer: ep=0x82, len=4096, timeout=1100, data=0x100104f0
usb_bulk_read:ioctl - received 8 bytes
usb_bulk_write:ioctl - send 122 bytes
usbdevfs_bulktransfer: ep=0x01, len=122, timeout=1100, data=0x100004f0
usb_bulk_write:ioctl - sent 122 bytes
usb_bulk_read:ioctl - request 4096 bytes
usbdevfs_bulktransfer: ep=0x82, len=4096, timeout=1100, data=0x100104f0
usb_bulk_read:ioctl - received 8 bytes
usb_bulk_write:ioctl - send 4096 bytes
usbdevfs_bulktransfer: ep=0x01, len=4096, timeout=1100, data=0x100004f0
===
At this point the process is stuck in D state and can not be killed.
~ # cat /proc/209/status
Name: puppy
State: D (disk sleep)
SleepAVG: 87%
Tgid: 209
Pid: 209
PPid: 160
TracerPid: 0
Uid: 0 0 0 0
Gid: 0 0 0 0
FDSize: 32
Groups:
VmSize: 1312 kB
VmLck: 0 kB
VmRSS: 504 kB
VmData: 656 kB
VmStk: 84 kB
VmExe: 36 kB
VmLib: 516 kB
VmPTE: 16 kB
Threads: 1
SigQ: 3/256
SigPnd: 00000000000000000000000000000100
ShdPnd: 00000000000000000000000000004102
SigBlk: 00000000000000000000000000000000
SigIgn: 00000000000000000000000000000000
SigCgt: 00000000000000000000000000000000
CapInh: 0000000000000000
CapPrm: 00000000fffffeff
CapEff: 00000000fffffeff
The timeout in the ioctl() request does not appear to have any effect -
the call never returns. Power cycling the USB device does not seem to
help anything. At best I get:
usb 1-1: USB disconnect, address 3
but the process is still hung. I need to reboot the machine in order to
be able to continue using usbfs.
Any ideas as to where I should start looking for problems? Is there any
extra debugging / logging I can turn on to help identify the source of
the problem?
I noticed that turning on the preemptible kernel option will cause the
following messages:
00:06:55 (none) kern.err kernel: scheduling while atomic:
puppy/0x10000001/204
Could this be related?
Thanks in advance.
Peter.
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