netdev - Re: [PATCH 06/12] bnx2x: Search VPD with pci_vpd_find_ro_info

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Message-ID: <53d92923-fa8f-aa2c-ff14-340f380018b1@gmail.com>
Date:   Tue, 24 Aug 2021 20:01:34 +0200
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Bjorn Helgaas <helgaas@...nel.org>
Cc:     Bjorn Helgaas <bhelgaas@...gle.com>,
        Ariel Elior <aelior@...vell.com>,
        Sudarsana Kalluru <skalluru@...vell.com>,
        GR-everest-linux-l2@...vell.com, Jakub Kicinski <kuba@...nel.org>,
        David Miller <davem@...emloft.net>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH 06/12] bnx2x: Search VPD with
 pci_vpd_find_ro_info_keyword()

On 24.08.2021 19:02, Bjorn Helgaas wrote:
> On Sun, Aug 22, 2021 at 03:54:23PM +0200, Heiner Kallweit wrote:
>> Use pci_vpd_find_ro_info_keyword() to search for keywords in VPD to
>> simplify the code.
>>
>> str_id_reg and str_id_cap hold the same string and are used in the same
>> comparison. This doesn't make sense, use one string str_id instead.
> 
> str_id_reg is printed with "%04x" (lower-case hex letters) and
> str_id_cap with "%04X" (upper-case hex letters), so the previous code
> would match either 0xabcd or 0xABCD.  After this patch, we'd match
> only the latter.
> 
Right, I missed this difference. strncasecmp() would be an easy solution.
Alternatively we could avoid this stringification and string comparison
by using kstrtouint_from_user():

kstrtouint_from_user(&vpd_data[rodi], kw_len, 16, &val)
if (val == PCI_VENDOR_ID_DELL)

But if there's no strong preference then I'd say we go the easy way.
Would you like me to re-send or are you going to adjust the patch?

> PCI_VENDOR_ID_DELL is 0x1028, so it shouldn't make any difference,
> which makes me wonder why somebody bothered with both.
> 
> But it does seem like a potential landmine to change the case
> sensitivity.  Maybe strncasecmp() instead?
> 
>> Signed-off-by: Heiner Kallweit <hkallweit1@...il.com>
>> ---
>>  .../net/ethernet/broadcom/bnx2x/bnx2x_main.c  | 57 +++++--------------
>>  1 file changed, 15 insertions(+), 42 deletions(-)
>>
>> diff --git a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c
>> index 0466adf8d..2c7bfc416 100644
>> --- a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c
>> +++ b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c
>> @@ -12189,11 +12189,10 @@ static int bnx2x_get_hwinfo(struct bnx2x *bp)
>>  
>>  static void bnx2x_read_fwinfo(struct bnx2x *bp)
>>  {
>> -	int i, block_end, rodi;
>> -	char str_id_reg[VENDOR_ID_LEN+1];
>> -	char str_id_cap[VENDOR_ID_LEN+1];
>> -	unsigned int vpd_len;
>> -	u8 *vpd_data, len;
>> +	char str_id[VENDOR_ID_LEN + 1];
>> +	unsigned int vpd_len, kw_len;
>> +	u8 *vpd_data;
>> +	int rodi;
>>  
>>  	memset(bp->fw_ver, 0, sizeof(bp->fw_ver));
>>  
>> @@ -12201,46 +12200,20 @@ static void bnx2x_read_fwinfo(struct bnx2x *bp)
>>  	if (IS_ERR(vpd_data))
>>  		return;
>>  
>> -	/* VPD RO tag should be first tag after identifier string, hence
>> -	 * we should be able to find it in first BNX2X_VPD_LEN chars
>> -	 */
>> -	i = pci_vpd_find_tag(vpd_data, vpd_len, PCI_VPD_LRDT_RO_DATA);
>> -	if (i < 0)
>> -		goto out_not_found;
>> -
>> -	block_end = i + PCI_VPD_LRDT_TAG_SIZE +
>> -		    pci_vpd_lrdt_size(&vpd_data[i]);
>> -	i += PCI_VPD_LRDT_TAG_SIZE;
>> -
>> -	rodi = pci_vpd_find_info_keyword(vpd_data, i, block_end,
>> -				   PCI_VPD_RO_KEYWORD_MFR_ID);
>> -	if (rodi < 0)
>> -		goto out_not_found;
>> -
>> -	len = pci_vpd_info_field_size(&vpd_data[rodi]);
>> -
>> -	if (len != VENDOR_ID_LEN)
>> +	rodi = pci_vpd_find_ro_info_keyword(vpd_data, vpd_len,
>> +					    PCI_VPD_RO_KEYWORD_MFR_ID, &kw_len);
>> +	if (rodi < 0 || kw_len != VENDOR_ID_LEN)
>>  		goto out_not_found;
>>  
>> -	rodi += PCI_VPD_INFO_FLD_HDR_SIZE;
>> -
>>  	/* vendor specific info */
>> -	snprintf(str_id_reg, VENDOR_ID_LEN + 1, "%04x", PCI_VENDOR_ID_DELL);
>> -	snprintf(str_id_cap, VENDOR_ID_LEN + 1, "%04X", PCI_VENDOR_ID_DELL);
>> -	if (!strncmp(str_id_reg, &vpd_data[rodi], VENDOR_ID_LEN) ||
>> -	    !strncmp(str_id_cap, &vpd_data[rodi], VENDOR_ID_LEN)) {
>> -
>> -		rodi = pci_vpd_find_info_keyword(vpd_data, i, block_end,
>> -						PCI_VPD_RO_KEYWORD_VENDOR0);
>> -		if (rodi >= 0) {
>> -			len = pci_vpd_info_field_size(&vpd_data[rodi]);
>> -
>> -			rodi += PCI_VPD_INFO_FLD_HDR_SIZE;
>> -
>> -			if (len < 32 && (len + rodi) <= vpd_len) {
>> -				memcpy(bp->fw_ver, &vpd_data[rodi], len);
>> -				bp->fw_ver[len] = ' ';
>> -			}
>> +	snprintf(str_id, VENDOR_ID_LEN + 1, "%04X", PCI_VENDOR_ID_DELL);
>> +	if (!strncmp(str_id, &vpd_data[rodi], VENDOR_ID_LEN)) {
>> +		rodi = pci_vpd_find_ro_info_keyword(vpd_data, vpd_len,
>> +						    PCI_VPD_RO_KEYWORD_VENDOR0,
>> +						    &kw_len);
>> +		if (rodi >= 0 && kw_len < sizeof(bp->fw_ver)) {
>> +			memcpy(bp->fw_ver, &vpd_data[rodi], kw_len);
>> +			bp->fw_ver[kw_len] = ' ';
>>  		}
>>  	}
>>  out_not_found:
>> -- 
>> 2.33.0
>>
>>