Re: [PATCH] Port SquashFS to 2.6

From: postmaster@lougher.demon.co.uk
Date: Sun Jul 20 2003 - 05:16:18 EST


joern@wohnheim.fh-wedel.de wrote:
> On Sat, 19 July 2003 22:40:22 -0700, junkio@cox.net wrote:
> > >>>>> "DD" == David Dillow <dave@thedillows.org> writes:
> >
> > DD> Hmm, isn't that 4K allocated on the stack? Ouch.
> >
> > Ouch indeed. I was not looking for these things (I was just
> > porting not fixing). Thank you for pointing it out. Have a
> > couple of questions:
> >

Thanks for sending the 2.6 patch, due to work pressure, I have had very little
time to do these things recently. I am still, however, actively developing
squashfs (a 1.3 with some improvements will be released soon), and I'd prefer
to do code fixes myself.
  
> > - Would it be an acceptable alternative here to use blocking
> > kmalloc upon entry with matching kfree before leaving?
> >
> > - I would imagine that the acceptable stack usage for functions
> > would depend on where they are called and what they call.
> > Coulc you suggest a rule-of-thumb number for
> > address_space_operations.readpage (say, would 1kB be OK but
> > not 3kB?)
>
> As a rule of thumb, stay below 1k or you will get regular email from
> me. :)

I tend to allocate (small) buffers on the stack, when their size does not
seem to warrant either: a globally kmalloced buffer and consequent locking,
or a locally kmalloced buffer kfreed on exit from the function, which seems
wasteful. However, if 1K is the perceived wisdom on stack limits, then I will
alter the code.

Phillip

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