svn commit: r212661 - head/sys/dev/aac

[Attilio Rao]

2010/9/15 Kostik Belousov <kostikbel at gmail.com>:
> On Wed, Sep 15, 2010 at 02:24:21PM +0000, Attilio Rao wrote:
>> Author: attilio
>> Date: Wed Sep 15 14:24:21 2010
>> New Revision: 212661
>> URL: http://svn.freebsd.org/changeset/base/212661
>>
>> Log:
>>   Fix bogus busying mechanism from cdevsw callbacks:
>>   - D_TRACKCLOSE may be used there as d_close() are expected to match up
>>     d_open() calls
> VFS is not very good at properly calling VOP_CLOSE(). As example, premature
> vnode reclaim due to devfs unmount would cause VOP_CLOSE() to be called
> only once despite the number of opens being  > 1.

Yes.
That makes implementing a similar semantic in drivers very difficult
and not very well fixable, in particular within the d_* callbacks.
I'm seriously wondering if we might just make a shortcut just for
supporting such a feature (busying the device on real devfs entry
activity) as several of them may be needing and may be probabilly
needing to be 100%.
Luckilly, it seems that such paths are not experienced very frequently.

Attilio


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