linux-kernel - Re: [PATCH v2 5/5] iommu/amd - Add a debugfs entry to specify a IOMMU device table entry

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Message-ID: <CAHp75VcuYamhrEu=B1zeFpz6s1vGfZaMyonYK6p_Y_EJF4=4Ng@mail.gmail.com>
Date:   Tue, 13 Mar 2018 22:56:30 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Gary R Hook <gary.hook@....com>
Cc:     "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
        Joerg Roedel <joro@...tes.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 5/5] iommu/amd - Add a debugfs entry to specify a IOMMU
 device table entry

On Tue, Mar 13, 2018 at 8:54 PM, Gary R Hook <gary.hook@....com> wrote:
> On 03/13/2018 12:20 PM, Andy Shevchenko wrote:

>>> +       } else if (obuf[0] == '0' && obuf[1] == 'x') {
>>> +               n = sscanf(obuf, "%x", &amd_iommu_devid);
>>> +       } else {
>>> +               n = sscanf(obuf, "%d", &amd_iommu_devid);
>>> +       }

>> kstrtoint() ?

> I see various mechanisms for this sort of thing, and simply chose one.
> Am happy to use whatever is preferred.

sscanf() has an enormous overhead for cases like this.

simple

ret = kstrtoint();
if (ret)
 ... do error handling ...


-- 
With Best Regards,
Andy Shevchenko