Re: [PATCH] tpm: Make chip->{status,cancel,req_canceled} opt

[Jarkko Sakkinen <jarkko@kernel.org>]

On Thu, Mar 27, 2025 at 05:00:11PM +0200, Jarkko Sakkinen wrote:
> On Thu, Mar 27, 2025 at 10:12:36AM -0400, James Bottomley wrote:
> > On Thu, 2025-03-27 at 15:23 +0200, Jarkko Sakkinen wrote:
> > > On Thu, Mar 27, 2025 at 10:58:00AM +0100, Stefano Garzarella wrote:
> > [...]
> > > > > @@ -65,6 +89,7 @@ static ssize_t tpm_try_transmit(struct tpm_chip
> > > > > *chip, void *buf, size_t bufsiz)
> > > > > 	ssize_t len = 0;
> > > > > 	u32 count, ordinal;
> > > > > 	unsigned long stop;
> > > > > +	u8 status;
> > > > 
> > > > Why move `status` out of the do/while block?
> > > 
> > > I'm not a huge fan of stack allocations inside blocks, unless there
> > > is a particular reason to do so.
> > 
> > The move to scope based locking and freeing in cleanup.h necessitates
> > using scope based variables as well, so they're something we all have
> > to embrace.  They're also useful to tell the compiler when it can
> > reclaim the variable and they often create an extra stack frame that
> > allows the reclaim to be effective (even if the compiler can work out
> > where a variable is no longer reference, the space can't be reclaimed
> > if it's in the middle of an in-use stack frame).  I'd say the rule of
> > thumb should be only do something like this if it improves readability
> > or allows you to remove an additional block from the code.
> 
> Reclaiming here is only shift in the frame pointer, nothing to do with
> reclaiming resources or freeing locks. Consolidating value state into
> single location does improve readability as far as I'm concerned.

Anyhow, I reverted that change given the feedback :-)

Since I'm late sending PR, I'll put this patch to my 6.15 PR.

BR, Jarkko