From 76f3c032adad86aad26f8ad3eebc993b4ba32138 Mon Sep 17 00:00:00 2001
From: Heiner Kallweit <hkallweit1@gmail.com>
Date: Wed, 18 Aug 2021 20:59:31 +0200
Subject: [PATCH] PCI/VPD: Add pci_vpd_alloc()
Git-commit: 76f3c032adad86aad26f8ad3eebc993b4ba32138
References: git-fixes
Patch-mainline: v5.15-rc1

Several users of the VPD API use a fixed-size buffer and read the VPD into
it for further usage. This requires special handling for the case that the
buffer isn't big enough to hold the full VPD data.  Also the buffer is
often allocated on the stack, which isn't too nice.

Add pci_vpd_alloc() to dynamically allocate buffer of the correct size and
read VPD into it.

Link: https://lore.kernel.org/r/955ff598-0021-8446-f856-0c2c077635d7@gmail.com
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Oliver Neukum <oneukum@suse.com>
---
 drivers/pci/vpd.c   | 26 ++++++++++++++++++++++++++
 include/linux/pci.h |  9 +++++++++
 2 files changed, 35 insertions(+)

diff --git a/drivers/pci/vpd.c b/drivers/pci/vpd.c
index 3b0425fb49f5..7c3a097379bb 100644
--- a/drivers/pci/vpd.c
+++ b/drivers/pci/vpd.c
@@ -270,6 +270,32 @@ const struct attribute_group pci_dev_vpd_attr_group = {
 	.is_bin_visible = vpd_attr_is_visible,
 };
 
+void *pci_vpd_alloc(struct pci_dev *dev, unsigned int *size)
+{
+	unsigned int len = dev->vpd.len;
+	void *buf;
+	int cnt;
+
+	if (!dev->vpd.cap)
+		return ERR_PTR(-ENODEV);
+
+	buf = kmalloc(len, GFP_KERNEL);
+	if (!buf)
+		return ERR_PTR(-ENOMEM);
+
+	cnt = pci_read_vpd(dev, 0, len, buf);
+	if (cnt != len) {
+		kfree(buf);
+		return ERR_PTR(-EIO);
+	}
+
+	if (size)
+		*size = len;
+
+	return buf;
+}
+EXPORT_SYMBOL_GPL(pci_vpd_alloc);
+
 int pci_vpd_find_tag(const u8 *buf, unsigned int len, u8 rdt)
 {
 	int i = 0;
diff --git a/include/linux/pci.h b/include/linux/pci.h
index e752cc39a1fe..8c681e24be8b 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -2330,6 +2330,15 @@ static inline u8 pci_vpd_info_field_size(const u8 *info_field)
 	return info_field[2];
 }
 
+/**
+ * pci_vpd_alloc - Allocate buffer and read VPD into it
+ * @dev: PCI device
+ * @size: pointer to field where VPD length is returned
+ *
+ * Returns pointer to allocated buffer or an ERR_PTR in case of failure
+ */
+void *pci_vpd_alloc(struct pci_dev *dev, unsigned int *size);
+
 /**
  * pci_vpd_find_tag - Locates the Resource Data Type tag provided
  * @buf: Pointer to buffered vpd data
-- 
2.26.2