RE: [PATCH 05/12] bnx2x: Read VPD with pci_vpd_alloc()

Hi Heiner,

Definition of pci_vpd_alloc() is below as per repo "git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci.git" and   branch wip/heiner-vpd-api
void *pci_vpd_alloc(struct pci_dev *dev, unsigned int *size)
{
        unsigned int len = dev->vpd.len;
        void *buf;
--
--
        if (size)
                *size = len;
}
Here is len is already part of pci_dev.  

So why cannot same be set in caller function i.e. vpd_len = pb->pdev->vpd.len

As vpd_data allocation done in PCI layer. 
It will be logical to also free vpd_data in PCI layer.

--pk

On 24.08.2021 16:20, Prabhakar Kushwaha wrote:

Hi Heiner,

quoted

-----Original Message-----
From: Heiner Kallweit <hkallweit1@gmail.com>
Sent: Sunday, August 22, 2021 7:23 PM
To: Bjorn Helgaas <bhelgaas@google.com>; Ariel Elior <redacted>;
Sudarsana Reddy Kalluru [off-list ref]; GR-everest-linux-l2 <GR-
everest-linux-l2@marvell.com>; Jakub Kicinski [off-list ref]; David
Härdeman [off-list ref]
Cc: linux-pci@vger.kernel.org; netdev@vger.kernel.org
Subject: [PATCH 05/12] bnx2x: Read VPD with pci_vpd_alloc()

External Email

----------------------------------------------------------------------
Use pci_vpd_alloc() to dynamically allocate a properly sized buffer and
read the full VPD data into it.

This simplifies the code, and we no longer have to make assumptions about
VPD size.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
---
 drivers/net/ethernet/broadcom/bnx2x/bnx2x.h   |  1 -
 .../net/ethernet/broadcom/bnx2x/bnx2x_main.c  | 44 +++++--------------
 2 files changed, 10 insertions(+), 35 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/bnx2x/bnx2x.h

b/drivers/net/ethernet/broadcom/bnx2x/bnx2x.h
index d04994840..e789430f4 100644

--- a/drivers/net/ethernet/broadcom/bnx2x/bnx2x.h
+++ b/drivers/net/ethernet/broadcom/bnx2x/bnx2x.h

@@ -2407,7 +2407,6 @@ void bnx2x_igu_clear_sb_gen(struct bnx2x *bp, u8

func, u8 idu_sb_id,
 #define ETH_MAX_RX_CLIENTS_E2		ETH_MAX_RX_CLIENTS_E1H
 #endif

-#define BNX2X_VPD_LEN			128
 #define VENDOR_ID_LEN			4

 #define VF_ACQUIRE_THRESH		3

diff --git a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c

b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c
index 6d9813491..0466adf8d 100644

--- a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c
+++ b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c

@@ -12189,50 +12189,29 @@ static int bnx2x_get_hwinfo(struct bnx2x *bp)

 static void bnx2x_read_fwinfo(struct bnx2x *bp)
 {
-	int cnt, i, block_end, rodi;
-	char vpd_start[BNX2X_VPD_LEN+1];
+	int i, block_end, rodi;
 	char str_id_reg[VENDOR_ID_LEN+1];
 	char str_id_cap[VENDOR_ID_LEN+1];
-	char *vpd_data;
-	char *vpd_extended_data = NULL;
-	u8 len;
+	unsigned int vpd_len;
+	u8 *vpd_data, len;

-	cnt = pci_read_vpd(bp->pdev, 0, BNX2X_VPD_LEN, vpd_start);
 	memset(bp->fw_ver, 0, sizeof(bp->fw_ver));

-	if (cnt < BNX2X_VPD_LEN)
-		goto out_not_found;
+	vpd_data = pci_vpd_alloc(bp->pdev, &vpd_len);

Definition of pci_vpd_alloc() is below as per repo "git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci.git" and   branch wip/heiner-vpd-api
void *pci_vpd_alloc(struct pci_dev *dev, unsigned int *size)
{
        unsigned int len = dev->vpd.len;
        void *buf;
--
--
        if (size)
                *size = len;
}
Here is len is already part of pci_dev.  

So why cannot same be set in caller function i.e. vpd_len = pb->pdev->vpd.len

Internals of struct pci_vpd shouldn't be referenced outside PCI core.
Also you can't use vpd.len w/o checking vpd.cap.
pci_vpd_alloc() encapsulates these internals.

quoted

+	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_start, BNX2X_VPD_LEN,
PCI_VPD_LRDT_RO_DATA);
+	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_start[i]);
-
+		    pci_vpd_lrdt_size(&vpd_data[i]);
 	i += PCI_VPD_LRDT_TAG_SIZE;

-	if (block_end > BNX2X_VPD_LEN) {
-		vpd_extended_data = kmalloc(block_end, GFP_KERNEL);
-		if (vpd_extended_data  == NULL)
-			goto out_not_found;
-
-		/* read rest of vpd image into vpd_extended_data */
-		memcpy(vpd_extended_data, vpd_start, BNX2X_VPD_LEN);
-		cnt = pci_read_vpd(bp->pdev, BNX2X_VPD_LEN,
-				   block_end - BNX2X_VPD_LEN,
-				   vpd_extended_data + BNX2X_VPD_LEN);
-		if (cnt < (block_end - BNX2X_VPD_LEN))
-			goto out_not_found;
-		vpd_data = vpd_extended_data;
-	} else
-		vpd_data = vpd_start;
-
-	/* now vpd_data holds full vpd content in both cases */
-
 	rodi = pci_vpd_find_info_keyword(vpd_data, i, block_end,
 				   PCI_VPD_RO_KEYWORD_MFR_ID);
 	if (rodi < 0)

@@ -12258,17 +12237,14 @@ static void bnx2x_read_fwinfo(struct bnx2x *bp)

 			rodi += PCI_VPD_INFO_FLD_HDR_SIZE;

-			if (len < 32 && (len + rodi) <= BNX2X_VPD_LEN) {
+			if (len < 32 && (len + rodi) <= vpd_len) {
 				memcpy(bp->fw_ver, &vpd_data[rodi], len);
 				bp->fw_ver[len] = ' ';
 			}
 		}
-		kfree(vpd_extended_data);
-		return;
 	}
 out_not_found:
-	kfree(vpd_extended_data);
-	return;
+	kfree(vpd_data);

As vpd_data allocation done in PCI layer. 
It will be logical to also free vpd_data in PCI layer.

The idea is right, however a call like pci_vpd_free() would be a one-liner
calling kfree(), and I doubt it's really worth it.

--pk

Heiner