[PATCH] Add locking to twe(4) so it no longer uses Giant

[John Baldwin]

On 8/10/12 9:52 AM, Mike Tancsa wrote:
> On 8/10/2012 9:31 AM, John Baldwin wrote:
>> On 8/9/12 5:04 PM, Mike Tancsa wrote:
>>> Start up the tw_cli client
>>>
>>> 0{offsite2}# tw_cli
>>> //offsite2> show
>>>
>>> Ctl   Model        (V)Ports  Drives   Units   NotOpt  RRate   VRate  BBU
>>> ------------------------------------------------------------------------
>>> c0    9650SE-2LP   2         2        1       0       1       1      -
>>>
>>>
>>> //offsite2> exit
>>> 0{offsite2}# ls -l /dev/tw*
>>> crw-------  1 root  operator  -   0,  37 Aug  9 16:58 /dev/twa0
>>> crw-r-----  1 root  operator  -   0, 174 Aug  9 17:00 /dev/twed0
>>> 0{offsite2}#
>>>
>>>
>>> It then disappears ?!
>>
>> Bizarre, it seems to disappear while tw_cli is running?  I'm curious if
>> 'rm -W /dev/twe0' brings it back?
> 
> nada
> 0{offsite2}# rm -W /dev/twe0
> rm: /dev/twe0: No such file or directory
> 1{offsite2}# rm -W /dev/twe0
> rm: /dev/twe0: No such file or directory
> 1{offsite2}# ls -l /dev/twe*
> crw-r-----  1 root  operator  -   0, 174 Aug  9 17:00 /dev/twed0
> 0{offsite2}#
> 
>>
>> If so, it might be interesting to see a ktrace of tw_cli.
>>
> 
> I just ran ktrace tw_cli
> File is available at
> 
> http://www.tancsa.com/misc/ktrace.out
> and
> http://www.tancsa.com/misc/ktrace.txt

  5972 tw_cli   CALL
__sysctl(0x7fffffffd798,0x2,0x7fffffffd7a0,0x7fffffffd790,0x7fffffffd960,0x16)
  5972 tw_cli   SCTL  "sysctl.name2oid"
  5972 tw_cli   RET   __sysctl -1 errno 2 No such file or directory
  5972 tw_cli   CALL  unlink(0x7fffffffd9d0)
  5972 tw_cli   NAMI  "/dev/twe0"
  5972 tw_cli   RET   unlink 0
...

Oh!  I moved the sysctl's for twe out of hw and under the device node.
That seem to have broken tw_cli.  I will revert that and generate an
updated patch.

Try http://www.FreeBSD.org/~jhb/patches/twe_locking2.patch

-- 
John Baldwin