linux-kernel - Re: [PATCH RESEND 2/3] tpm: replace dynamically allocated bios

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Date:   Tue, 11 Oct 2016 22:49:56 +0530
From:   Nayna <nayna@...ux.vnet.ibm.com>
To:     Jason Gunthorpe <jgunthorpe@...idianresearch.com>,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Cc:     Peter Huewe <peterhuewe@....de>,
        Marcel Selhorst <tpmdd@...horst.net>,
        "moderated list:TPM DEVICE DRIVER" 
        <tpmdd-devel@...ts.sourceforge.net>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH RESEND 2/3] tpm: replace dynamically allocated bios_dir
 with a static array



On 10/11/2016 10:23 PM, Jason Gunthorpe wrote:
> On Tue, Oct 11, 2016 at 02:23:15PM +0300, Jarkko Sakkinen wrote:
>>>> +	chip->bios_dir[cnt] =
>>>>   	    securityfs_create_file("ascii_bios_measurements",
>>>> -				   S_IRUSR | S_IRGRP, tpm_dir,
>>>> +				   S_IRUSR | S_IRGRP, chip->bios_dir[0],
>>>>   				   (void *)&tpm_ascii_b_measurments_seqops,
>>>>   				   &tpm_bios_measurements_ops);
>
>>>> +	if (is_bad(chip->bios_dir[cnt]))
>>>> +		goto err;
>
>>>> +err:
>>>> +	chip->bios_dir[cnt] = NULL;
>>>
>>> The updated patch looks fine.
>>> Just, I am not sure if NULL assignment is needed.
>>
>> It's not needed.
>
> It is required to switch an ERR_PTR to NULL, see is_bad()

My understanding is that securityfs_remove() takes care of both NULL and 
ERR_PTR().

 From securityfs_remove():

  if (!dentry || IS_ERR(dentry))
                 return;

Thanks & Regards,
   - Nayna

>
> The original version that used a counter in chip did not need it.
>
> Jason
>