linux-kernel - Re: [PATCH 22/24] uaccess: add memzero

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Message-ID: <20200520212807.GD23230@ZenIV.linux.org.uk>
Date:   Wed, 20 May 2020 22:28:07 +0100
From:   Al Viro <viro@...iv.linux.org.uk>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Christoph Hellwig <hch@...radead.org>,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        vkuznets@...hat.com, Joerg Roedel <jroedel@...e.de>
Subject: Re: [PATCH 22/24] uaccess: add memzero_user

On Wed, May 20, 2020 at 11:13:36PM +0200, Paolo Bonzini wrote:
> On 20/05/20 22:40, Christoph Hellwig wrote:
> > On Wed, May 20, 2020 at 01:21:43PM -0400, Paolo Bonzini wrote:
> >> +			unsafe_put_user(val, (unsigned long __user *) from, err_fault);
> > This adds a way too long line.  In many ways it would be much nicer if
> > you used an unsigned long __user * variable internally, a that would
> > remove all these crazy casts and actually make the code readable.
> > 
> 
> Good idea, thanks.

Unless I'm seriously misreading that patch, it could've been done as

static inline __must_check int memzero_user(void __user *addr, size_t size)
{
	return clear_user(addr, n) ? -EFAULT : 0;
}

What am I missing?