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SubjectRe: [RFC][PATCH -mm take2 3/5] add interface for netconsole using sysfs
>> create a sysfs entry for netconsole in /sys/class/misc.
>> This entry has elements related to netconsole as follows.
>> You can change configuration of netconsole(writable attributes such as IP
>> address, port number and so on) and check current configuration of netconsole.
>> -+- /sys/class/misc/
>> |-+- netconsole/
>> |-+- port1/
>> | |--- id [r--r--r--] unique port id
>> | |--- remove [-w-------] if you write something to "remove",
>> | | this port is removed.
> IMHO this kind of "magic side effect" is a misuse of sysfs. and would
> make proper locking
> impossible. How do you deal with the dangling reference to the
> netconsole object?

I manage the reference by using a list.
If you write something to "remove",
firstly the port entry is removed from sysfs and then
the reference is removed from the list and a resource of the port is freed.

> f= open (... netconsole/port1/remove")
> write(f, "", 1)
> sleep(2)
> write(f, "", 1) .... this probably would crash...
> Maybe having a state variable/sysfs file so you could setup the port and
> turn it on/off with write.

You are right.
When I tested above program, my machine crashed.

I'm going to rethink the interface for netconsole.

Thanks for your comments.
Keiichi KII
NEC Corporation OSS Promotion Center

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