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

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Date:   Tue, 24 Aug 2021 13:47:38 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Heiner Kallweit <hkallweit1@...il.com>
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 Tue, Aug 24, 2021 at 08:01:34PM +0200, Heiner Kallweit wrote:
> 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?

I adjusted it, thanks!

> > 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
> >>
> >>
>