zpcimon: Monitor for hotplug of NVMes to trigger SMART collection

Use libudev to monitor for "change" events in the "nvme" subsystem that
use the "pcie" transport to trigger NVMe SMART data collection. Only
collect data from the NVMe referenced by the udev event.

Assisted-by: IBM Bob:1.0.1
Reviewed-by: Jan Höppner <hoeppner@linux.ibm.com>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>

README.md

@@ -325,7 +325,7 @@ build options:
 |              |                    | rust/pvattest, rust/pvsecret,          |
 | libxml2      | `HAVE_LIBXML2`     | libkmipclient                          |
 | systemd      | `HAVE_SYSTEMD`     | hsavmcore                              |
-| libudev      | `HAVE_LIBUDEV`     | cpacfstatsd                            |
+| libudev      | `HAVE_LIBUDEV`     | cpacfstatsd, zpcimon                   |
 | libnl3       | `HAVE_LIBNL3`      | zpcimon                                |
 | libnvme      | `HAVE_LIBNVME`     | zpcimon                                |
 

zpcimon/Makefile

@@ -39,6 +39,16 @@ check_dep_libnvme:
 BUILDTARGET += check_dep_libnvme
 endif # HAVE_LIBNVME
 
+ifneq (${HAVE_LIBUDEV},0)
+check_dep_libudev:
+	$(call check_dep, \
+		"zpcimon", \
+		"libudev.h", \
+		"systemd-devel", \
+		"HAVE_LIBNVME=0")
+BUILDTARGET += check_dep_libudev
+endif # HAVE_LIBUDEV
+
 ifeq (${HAVE_OPENSSL},0)
 
 all:
@@ -61,6 +71,12 @@ all:
 install:
 	$(SKIP) HAVE_LIBNVME=0
 
+else ifeq (${HAVE_LIBUDEV},0)
+all:
+	$(SKIP) HAVE_LIBUDEV=0
+
+install:
+	$(SKIP) HAVE_LIBUDEV=0
 else
 
 ifneq ($(shell sh -c 'command -v pkg-config'),)
@@ -76,6 +92,7 @@ LIB_LFLAGS += $(shell $(PKG_CONFIG) --silence-errors --libs libnl-route-3.0)
 
 LIB_LFLAGS += $(shell $(PKG_CONFIG) --silence-errors --libs libcrypto)
 LIB_LFLAGS += $(shell $(PKG_CONFIG) --silence-errors --libs libnvme)
+LIB_LFLAGS += $(shell $(PKG_CONFIG) --silence-errors --libs libudev)
 else
 LIB_CFLAGS += -I /usr/include/libnl3/
 LIB_LFLAGS += -lnl-route-3 -lnl-genl-3 -lnl-3
@@ -84,6 +101,7 @@ LIB_CFLAGS += -I /usr/include/openssl/
 LIB_LFLAGS += -lcrypto
 
 LIB_LFLAGS += -lnvme
+LIB_LFLAGS += -ludev
 endif
 
 ALL_CPPFLAGS += $(LIB_CFLAGS)

zpcimon/nvmemon.c

@@ -15,6 +15,7 @@
 #include <string.h>
 #include <unistd.h>
 #include <libnvme.h>
+#include <libudev.h>
 
 #include "lib/pci_list.h"
 #include "lib/pci_sclp.h"
@@ -195,6 +196,115 @@ exit_free_addr:
 	return rc;
 }
 
+static int nvmemon_open_monitor(struct zpcimon_ctx *ctx)
+{
+	struct nvmemon_ctx *nctx = &ctx->nvmemon_ctx;
+	int ret = -EINVAL;
+
+	nctx->udev = udev_new();
+	if (!nctx->udev)
+		return -ENOMEM;
+
+	nctx->mon = udev_monitor_new_from_netlink(nctx->udev, "kernel");
+	if (!nctx->mon) {
+		ret = -ENOMEM;
+		goto error_udev;
+	}
+
+	if (udev_monitor_filter_add_match_subsystem_devtype(nctx->mon, "nvme", NULL) < 0)
+		goto error_mon;
+
+	/* Note: This explicit udev_monitor_enable_receiving() is deprecated and not needed anymore
+	 * in udev v257+. It's harmless though so we do it for easier backporting.
+	 */
+	if (udev_monitor_enable_receiving(nctx->mon) < 0)
+		goto error_mon;
+
+	return 0;
+
+error_mon:
+	udev_monitor_unref(nctx->mon);
+	nctx->mon = NULL;
+error_udev:
+	udev_unref(nctx->udev);
+	nctx->udev = NULL;
+	return ret;
+}
+
+static int nvmemon_get_monitor_fd(struct zpcimon_ctx *ctx)
+{
+	struct nvmemon_ctx *nctx = &ctx->nvmemon_ctx;
+
+	if (!nctx->mon)
+		return -1;
+	return udev_monitor_get_fd(nctx->mon);
+}
+
+static void nvmemon_monitor_fd_handle(struct zpcimon_ctx *ctx)
+{
+	const char *action, *transport, *event_pci_addr;
+	struct nvmemon_ctx *nctx = &ctx->nvmemon_ctx;
+	struct udev_device *dev, *pci_dev;
+	struct zpci_dev *zdev;
+	char *zdev_pci_addr;
+
+	dev = udev_monitor_receive_device(nctx->mon);
+	if (!dev)
+		return;
+
+	action = udev_device_get_action(dev);
+	transport = udev_device_get_property_value(dev, "NVME_TRTYPE");
+
+	/* Change events are late enough that the /dev/nvmeX is ready for
+	 * reading SMART data and we're only interested in directly PCIe
+	 * attached NVMes
+	 */
+	if (action && strcmp(action, "change") == 0 && transport &&
+	    strcmp(transport, "pcie") == 0) {
+		pci_dev = udev_device_get_parent_with_subsystem_devtype(dev, "pci", NULL);
+		if (!pci_dev)
+			goto out;
+		event_pci_addr = udev_device_get_sysname(pci_dev);
+		if (!event_pci_addr)
+			goto out;
+
+		zpci_list_reload(&ctx->zpci_list);
+		if (ctx->zpci_list) {
+			util_list_iterate(ctx->zpci_list, zdev) {
+				if (zdev->pft != ZPCI_PFT_NVME)
+					continue;
+				zdev_pci_addr = zpci_pci_addr(zdev);
+				if (strcmp(zdev_pci_addr, event_pci_addr) == 0) {
+					free(zdev_pci_addr);
+					nvmemon_collect_adapter_data(ctx, zdev);
+					break;
+				}
+				free(zdev_pci_addr);
+			}
+		}
+	}
+out:
+	udev_device_unref(dev);
+}
+
+static void nvmemon_close_monitor(struct zpcimon_ctx *ctx)
+{
+	struct nvmemon_ctx *nctx = &ctx->nvmemon_ctx;
+
+	if (nctx->mon) {
+		udev_monitor_unref(nctx->mon);
+		nctx->mon = NULL;
+	}
+	if (nctx->udev) {
+		udev_unref(nctx->udev);
+		nctx->udev = NULL;
+	}
+}
+
 const struct zpcimon_ops nvmemon_ops = {
 	.collect_adapter_data = nvmemon_collect_adapter_data,
+	.open_monitor = nvmemon_open_monitor,
+	.get_monitor_fd = nvmemon_get_monitor_fd,
+	.monitor_fd_handle = nvmemon_monitor_fd_handle,
+	.close_monitor = nvmemon_close_monitor,
 };

zpcimon/nvmemon.h

@@ -7,7 +7,12 @@
 #ifndef ZPCIMON_NVMEMON_H
 #define ZPCIMON_NVMEMON_H
 
-struct nvmemon_ctx {};
+#include <libudev.h>
+
+struct nvmemon_ctx {
+	struct udev *udev;
+	struct udev_monitor *mon;
+};
 
 extern const struct zpcimon_ops nvmemon_ops;
 #endif /* ZPCIMON_NVMEMON_H */