Re: New DRM driver model - gets rid of DRM() macros!

Keith Whitwell
2004-09-29T13:36:44Z

Christoph Hellwig wrote:
> On Wed, Sep 29, 2004 at 02:29:24PM +0100, Keith Whitwell wrote:
>
>>Christoph Hellwig wrote:
>>
>>
>>> - drm_flush is a noop. a NULL ->flush does the same thing, just easier
>>> - dito or ->poll
>>> - dito for ->read
>>
>>Pretty sure you couldn't get away with null for these in 2.4, at least.
>
>
> Umm, of course you could. There's only a hanfull instance defining a
> ->flush at all. Similarly all file_ops for regular files and many char
> devices don't have ->poll. no ->read is pretty rare but 2.4 chæcks it
> aswell.

I tried it, led to crashes (panics, I guess) & the change had to be reverted.
On reverting the crashes stopped. This was for poll and read:

revision 1.12
date: 2003-04-23 23:42:28 +0000; author: keithw; state: Exp; lines: +13 -0
Install dummy/noop read & poll fops unless the driver has replacements.
----------------------------
revision 1.11
date: 2003-04-22 08:06:13 +0000; author: keithw; state: Exp; lines: +0 -94
remove DRM read, poll and write_string

I didn't do any more investigation & the behaviour may well be different
nowadays.

Keith