File s390-tools-sles15sp1-08-zpcictl-Read-device-link-to-obtain-device-address.patch of Package s390-tools.13271

Subject: zpcictl: Read device link to obtain device address
From: Jan Hoeppner <jan.hoeppner@de.ibm.com>

Summary:     zpcictl: Add tool to manage PCI devices
Description: Use the zpcictl tool to manage PCI devices on the IBM Z
             platform.  Initial functions include generating firmware
             error logs, resetting PCI devices, and preparing a device
             for further repair actions.
Upstream-ID: e2a8d85916fb77d2a9b41253446973cd97107c42
Problem-ID:  RAS1703

Upstream-Description:

             zpcictl: Read device link to obtain device address

             The address sysfs attribute might not be present on some older kernel
             levels. Read the device link instead using readlink() to obtain the
             address.

             Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>


Signed-off-by: Jan Hoeppner <jan.hoeppner@de.ibm.com>
---
 zpcictl/zpcictl.c |   27 ++++++++++++++++++---------
 1 file changed, 18 insertions(+), 9 deletions(-)

--- a/zpcictl/zpcictl.c
+++ b/zpcictl/zpcictl.c
@@ -172,13 +172,16 @@ static void sysfs_write_data(struct zpci
 	free(path);
 }
 
+/* lstat() doesn't work for sysfs files, so we have to work with a fixed size */
+#define READLINK_SIZE	256
+
 static void sysfs_get_slot_addr(const char *dev, char *slot)
 {
+	char device[READLINK_SIZE], *result;
 	unsigned int major, minor;
 	struct stat dev_stat;
-	char addr[13];
+	ssize_t len;
 	char *path;
-	FILE *fp;
 
 	if (stat(dev, &dev_stat) != 0) {
 		errx(EXIT_FAILURE, "Could not get stat information for %s: %s",
@@ -187,15 +190,21 @@ static void sysfs_get_slot_addr(const ch
 	major = major(dev_stat.st_rdev);
 	minor = minor(dev_stat.st_rdev);
 
-	path = util_path_sysfs("dev/char/%u:%u/address", major, minor);
-	fp = fopen(path, "r");
-	if (!fp)
-		fopen_err(path);
-	fscanf(fp, "%s", addr);
-	fclose(fp);
+	path = util_path_sysfs("dev/char/%u:%u/device", major, minor);
+	len = readlink(path, device, READLINK_SIZE - 1);
 	free(path);
+	if (len != -1)
+		device[len] = '\0';
+	else
+		errx(EXIT_FAILURE, "Could not read device link for %s", dev);
+
+	result = strrchr(device, '/');
+	if (result)
+		result++;
+	else
+		result = device;
 
-	strcpy(slot, addr);
+	strcpy(slot, result);
 }
 
 static void get_device_node(struct zpci_device *pdev)