linux-kernel - Re: [PATCH 1/7] staging: fsl-mc: MC bus IRQ support

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Date:	Tue, 5 May 2015 19:40:11 +0300
From:	Dan Carpenter <dan.carpenter@...cle.com>
To:	Jose Rivera <German.Rivera@...escale.com>
Cc:	"devel@...verdev.osuosl.org" <devel@...verdev.osuosl.org>,
	Stuart Yoder <stuart.yoder@...escale.com>,
	"bhamciu1@...escale.com" <bhamciu1@...escale.com>,
	"arnd@...db.de" <arnd@...db.de>,
	"bhupesh.sharma@...escale.com" <bhupesh.sharma@...escale.com>,
	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"agraf@...e.de" <agraf@...e.de>,
	"nir.erez@...escale.com" <nir.erez@...escale.com>,
	"itai.katz@...escale.com" <itai.katz@...escale.com>,
	Scott Wood <scottwood@...escale.com>,
	"R89243@...escale.com" <R89243@...escale.com>,
	Richard Schmitt <richard.schmitt@...escale.com>
Subject: Re: [PATCH 1/7] staging: fsl-mc: MC bus IRQ support

On Tue, May 05, 2015 at 04:08:49PM +0000, Jose Rivera wrote:
> > Subject: Re: [PATCH 1/7] staging: fsl-mc: MC bus IRQ support
> > 
> > On Mon, May 04, 2015 at 10:09:08PM +0000, Jose Rivera wrote:
> > > > > +		WARN_ON((int16_t)irq_count < 0);
> > > >
> > > > This code is doing "WARN_ON(test_bit(15, (unsigned long
> > *)&irq_count));".
> > > > That seems like nonsense.  Anyway, just delete the WARN_ON().
> > > >
> > > I disagree. This WARN_ON is checking that irq_count is in the expected
> > > range (it fits in int16_t as a positive number). The
> > > dprc_scan_objects() function expects irq_count to be of type "unsigned
> > > int" (which is 32-bit unsigned)
> > >
> > 
> > You're not allowed to disagree because it's a testable thing and not an
> > opinion about style or something.  :P  What you want is:
> > 
> > 	WARN_ON(irq_count > SHRT_MAX);
> > 
> I see your point now. The check "(int16_t)irq_count < 0)" will not be able
> to catch 0x10000 > 0x7fff, but "irq_count > SHRT_MAX) will. So I'll
> make the suggested change, but I would prefer to use S16_MAX rather than 
> SHRT_MAX.
> 

Huh?  I didn't even know about the S16_MAX definition.  There are
literally no users of it in the kernel.  It's not very fair because
there are few users of SHRT_MAX.  But there are literally no users of
S32_MAX in the kernel and 358 users of INT_MAX.

Don't insist that you must be special and different from everyone else.

> > > > to read what "goto error;" does.  The error handling here calls
> > > > devm_kfree() which is not needed...  devm_ functions automatically
> > > > clean up after themselves.  This seems a pattern throughout.  Do a
> > > > search for
> > > > devm_free() and see which ones are really needed or not.
> > > >
> > > I know that memory allocated with devm_kzalloc() is freed at the end
> > > of the lifetime of the device it is attached to. However, in error
> > > paths, why wait until the device is destroyed? Why not free the memory
> > > earlier so that it can be used for other purposes?
> > 
> Why then do the devm_kfree() function exist?
> 
> I will not remove the devm_free() calls unless the upstream maintainer
> requires me to do so.

I'm not saying remove them all.  I'm saying:

1)  I am concerned that you seem to thing devm_ is garbage collection.
2)  Remove the ones which are not needed, because it is a lot of work
    for me to figure this out so I was hoping you could do it.

regards,
dan carpenter

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