Re: [PATCH] Remove process freezer from suspend to RAM pathway

Matthew Garrett wrote:

On Tue, Jul 03, 2007 at 06:21:42PM -0400, Alan Stern wrote:

quoted

On Tue, 3 Jul 2007, Matthew Garrett wrote:

quoted

We're used to the idea of applications blocking when a resource they're using goes away - NFS has done it forever. You persist in evading my point.  I'm not worried about applications;  I'm worried about drivers.

Let me put it explicitly: You're writing a driver.  You're working on
the read, write, or probe method.  You add code to check if a system
sleep is underway.  Suppose the answer is Yes -- what does your driver
do next?

Leave the process blocked and defer any i/o until after resume. Why does it need to be any more complicated than that?

It gets complicated when this has to be added and TESTED in EVERY driver. The implied contract for drivers previously was that their device would not get accessed after it was suspended until it had been resumed first. This proposed change violates that.

I don't think this sort of handling is something that individual drivers should have to deal with (at least not ones that are part of a framework like USB, libata, etc.)

-- 
Robert Hancock      Saskatoon, SK, Canada
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