[openib-general] Some Missing Features from mthca/user MAD access

[Michael S. Tsirkin]

Hello!
Quoting r. shaharf (shaharf at voltaire.com) "RE: [openib-general] Some Missing Features from mthca/user MAD access":
> > > After consideration, I think the proper way is add a reference count
> When did ioctl go out of fashion? What is the big difference between
> ioctl and an embedded field in the umad structure? Both are binary
> parameters.

I think I agree that the format of data you are passing to write
must be either ascii or 

> Personally I think that non binary format is better when applicable -
> this mean issm file (you can say it is Plan9 style...). It would not
> necessarily use the open method. You may want to use the write method
> and to enable everyone read the file. This read may return the pid of
> the owner (== the first to write something into the file). 

[... ]

Ugh ... reads returning a value different from write.

In my humble opinion, the cleanest approach would be to simply have
a file which we can write 1 toset is sm and 0 to clean is sm,
read returning the current value.

Close would clean the bit, if set.

If set to 1, write of 1 would fail.

I think this is almost implementable over sysfs, except that
we dont get a hook on "close". Maybe we shall just try to add
a "close" hook to sysfs, and push it upstream?

MST