[dpdk-dev] [PATCH v10 6/8] eal: add failure handle mechanism for hotplug

[Jeff Guo]

The mechanism can initially register the sigbus handler after the device
event monitor is enabled. When a sigbus error is captured, the mechanism
will check the failure address and accordingly remap the invalid memory
for the corresponding device. It could prevent the application from
crashing when a device is hotplugged out.

By this patch, users could call below new added APIs to enable/disable
the device failure handle mechanism:
  - rte_dev_hotplug_handle_enable
  - rte_dev_hotplug_handle_disable

Signed-off-by: Jeff Guo <jia.guo at intel.com>
---
v10->v9:
add new APIs to enable/disable hotplug handling
---
 doc/guides/rel_notes/release_18_08.rst  |   5 +
 lib/librte_eal/bsdapp/eal/eal_dev.c     |  14 +++
 lib/librte_eal/common/eal_private.h     |  26 ++++++
 lib/librte_eal/common/include/rte_dev.h |  26 ++++++
 lib/librte_eal/linuxapp/eal/eal_dev.c   | 159 +++++++++++++++++++++++++++++++-
 lib/librte_eal/rte_eal_version.map      |   2 +
 6 files changed, 231 insertions(+), 1 deletion(-)

diff --git a/doc/guides/rel_notes/release_18_08.rst b/doc/guides/rel_notes/release_18_08.rst
index 321fa84..95dc1e0 100644
--- a/doc/guides/rel_notes/release_18_08.rst
+++ b/doc/guides/rel_notes/release_18_08.rst
@@ -117,6 +117,11 @@ New Features
 
   Added support for chained mbufs (input and output).
 
+* **Added failure handle mechanism for hotplug.**
+
+  ``rte_dev_hotplug_handle_enable`` and ``rte_dev_hotplug_handle_disable`` are
+  for enable or disable failure handle mechanism for hotplug.
+
 
 API Changes
 -----------
diff --git a/lib/librte_eal/bsdapp/eal/eal_dev.c b/lib/librte_eal/bsdapp/eal/eal_dev.c
index 1c6c51b..ae1c558 100644
--- a/lib/librte_eal/bsdapp/eal/eal_dev.c
+++ b/lib/librte_eal/bsdapp/eal/eal_dev.c
@@ -19,3 +19,17 @@ rte_dev_event_monitor_stop(void)
 	RTE_LOG(ERR, EAL, "Device event is not supported for FreeBSD\n");
 	return -1;
 }
+
+int
+rte_dev_hotplug_handle_enable(void)
+{
+	RTE_LOG(ERR, EAL, "Device event is not supported for FreeBSD\n");
+	return -1;
+}
+
+int
+rte_dev_hotplug_handle_disable(void)
+{
+	RTE_LOG(ERR, EAL, "Device event is not supported for FreeBSD\n");
+	return -1;
+}
diff --git a/lib/librte_eal/common/eal_private.h b/lib/librte_eal/common/eal_private.h
index 168430e..3cf0357 100644
--- a/lib/librte_eal/common/eal_private.h
+++ b/lib/librte_eal/common/eal_private.h
@@ -316,4 +316,30 @@ rte_devargs_layers_parse(struct rte_devargs *devargs,
  */
 int rte_bus_sigbus_handler(const void *failure_addr);
 
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Register the sigbus hander.
+ *
+ * @return
+ *   - On success, zero.
+ *   - On failure, a negative value.
+ */
+int
+rte_dev_sigbus_handler_register(void);
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Unregister the sigbus hander.
+ *
+ * @return
+ *   - On success, zero.
+ *   - On failure, a negative value.
+ */
+int
+rte_dev_sigbus_handler_unregister(void);
+
 #endif /* _EAL_PRIVATE_H_ */
diff --git a/lib/librte_eal/common/include/rte_dev.h b/lib/librte_eal/common/include/rte_dev.h
index b80a805..ff580a0 100644
--- a/lib/librte_eal/common/include/rte_dev.h
+++ b/lib/librte_eal/common/include/rte_dev.h
@@ -460,4 +460,30 @@ rte_dev_event_monitor_start(void);
 int __rte_experimental
 rte_dev_event_monitor_stop(void);
 
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Enable hotplug handling for devices.
+ *
+ * @return
+ *   - On success, zero.
+ *   - On failure, a negative value.
+ */
+int __rte_experimental
+rte_dev_hotplug_handle_enable(void);
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Disable hotplug handling for devices.
+ *
+ * @return
+ *   - On success, zero.
+ *   - On failure, a negative value.
+ */
+int __rte_experimental
+rte_dev_hotplug_handle_disable(void);
+
 #endif /* _RTE_DEV_H_ */
diff --git a/lib/librte_eal/linuxapp/eal/eal_dev.c b/lib/librte_eal/linuxapp/eal/eal_dev.c
index 1cf6aeb..fa5cb9b 100644
--- a/lib/librte_eal/linuxapp/eal/eal_dev.c
+++ b/lib/librte_eal/linuxapp/eal/eal_dev.c
@@ -4,6 +4,8 @@
 
 #include <string.h>
 #include <unistd.h>
+#include <fcntl.h>
+#include <signal.h>
 #include <sys/socket.h>
 #include <linux/netlink.h>
 
@@ -14,15 +16,31 @@
 #include <rte_malloc.h>
 #include <rte_interrupts.h>
 #include <rte_alarm.h>
+#include <rte_bus.h>
+#include <rte_eal.h>
+#include <rte_spinlock.h>
+#include <rte_errno.h>
 
 #include "eal_private.h"
 
 static struct rte_intr_handle intr_handle = {.fd = -1 };
 static bool monitor_started;
+static bool hotplug_handle;
 
 #define EAL_UEV_MSG_LEN 4096
 #define EAL_UEV_MSG_ELEM_LEN 128
 
+/*
+ * spinlock for device failure handle, if try to access bus or device,
+ * such as handle sigbus on bus or handle memory failure for device just use
+ * this lock. It could protect the bus and the device to avoid race condition.
+ */
+static rte_spinlock_t failure_handle_lock = RTE_SPINLOCK_INITIALIZER;
+
+static struct sigaction sigbus_action_old;
+
+static int sigbus_need_recover;
+
 static void dev_uev_handler(__rte_unused void *param);
 
 /* identify the system layer which reports this event. */
@@ -33,6 +51,49 @@ enum eal_dev_event_subsystem {
 	EAL_DEV_EVENT_SUBSYSTEM_MAX
 };
 
+static void
+sigbus_action_recover(void)
+{
+	if (sigbus_need_recover) {
+		sigaction(SIGBUS, &sigbus_action_old, NULL);
+		sigbus_need_recover = 0;
+	}
+}
+
+static void sigbus_handler(int signum, siginfo_t *info,
+				void *ctx __rte_unused)
+{
+	int ret;
+
+	RTE_LOG(INFO, EAL, "Thread[%d] catch SIGBUS, fault address:%p\n",
+		(int)pthread_self(), info->si_addr);
+
+	rte_spinlock_lock(&failure_handle_lock);
+	ret = rte_bus_sigbus_handler(info->si_addr);
+	rte_spinlock_unlock(&failure_handle_lock);
+	if (ret == -1) {
+		rte_exit(EXIT_FAILURE,
+			 "Failed to handle SIGBUS for hotplug, "
+			 "(rte_errno: %s)!", strerror(rte_errno));
+	} else if (ret == 1) {
+		if (sigbus_action_old.sa_handler)
+			(*(sigbus_action_old.sa_handler))(signum);
+		else
+			rte_exit(EXIT_FAILURE,
+				 "Failed to handle generic SIGBUS!");
+	}
+
+	RTE_LOG(INFO, EAL, "Success to handle SIGBUS for hotplug!\n");
+}
+
+static int cmp_dev_name(const struct rte_device *dev,
+	const void *_name)
+{
+	const char *name = _name;
+
+	return strcmp(dev->name, name);
+}
+
 static int
 dev_uev_socket_fd_create(void)
 {
@@ -147,6 +208,9 @@ dev_uev_handler(__rte_unused void *param)
 	struct rte_dev_event uevent;
 	int ret;
 	char buf[EAL_UEV_MSG_LEN];
+	struct rte_bus *bus;
+	struct rte_device *dev;
+	const char *busname = "";
 
 	memset(&uevent, 0, sizeof(struct rte_dev_event));
 	memset(buf, 0, EAL_UEV_MSG_LEN);
@@ -171,8 +235,43 @@ dev_uev_handler(__rte_unused void *param)
 	RTE_LOG(DEBUG, EAL, "receive uevent(name:%s, type:%d, subsystem:%d)\n",
 		uevent.devname, uevent.type, uevent.subsystem);
 
-	if (uevent.devname)
+	switch (uevent.subsystem) {
+	case EAL_DEV_EVENT_SUBSYSTEM_PCI:
+	case EAL_DEV_EVENT_SUBSYSTEM_UIO:
+		busname = "pci";
+		break;
+	default:
+		break;
+	}
+
+	if (uevent.devname) {
+		if (uevent.type == RTE_DEV_EVENT_REMOVE && hotplug_handle) {
+			rte_spinlock_lock(&failure_handle_lock);
+			bus = rte_bus_find_by_name(busname);
+			if (bus == NULL) {
+				RTE_LOG(ERR, EAL, "Cannot find bus (%s)\n",
+					busname);
+				return;
+			}
+
+			dev = bus->find_device(NULL, cmp_dev_name,
+					       uevent.devname);
+			if (dev == NULL) {
+				RTE_LOG(ERR, EAL, "Cannot find device (%s) on "
+					"bus (%s)\n", uevent.devname, busname);
+				return;
+			}
+
+			ret = bus->memory_failure_handler(dev);
+			rte_spinlock_unlock(&failure_handle_lock);
+			if (ret) {
+				RTE_LOG(ERR, EAL, "Can not handle hotplug for "
+					"device (%s)\n", dev->name);
+				return;
+			}
+		}
 		dev_callback_process(uevent.devname, uevent.type);
+	}
 }
 
 int __rte_experimental
@@ -220,5 +319,63 @@ rte_dev_event_monitor_stop(void)
 	close(intr_handle.fd);
 	intr_handle.fd = -1;
 	monitor_started = false;
+
 	return 0;
 }
+
+int
+rte_dev_sigbus_handler_register(void)
+{
+	sigset_t mask;
+	struct sigaction action;
+
+	rte_errno = 0;
+
+	sigemptyset(&mask);
+	sigaddset(&mask, SIGBUS);
+	action.sa_flags = SA_SIGINFO;
+	action.sa_mask = mask;
+	action.sa_sigaction = sigbus_handler;
+	sigbus_need_recover = !sigaction(SIGBUS, &action, &sigbus_action_old);
+
+	return rte_errno;
+}
+
+int
+rte_dev_sigbus_handler_unregister(void)
+{
+	rte_errno = 0;
+	sigbus_need_recover = 1;
+
+	sigbus_action_recover();
+
+	return rte_errno;
+}
+
+int
+rte_dev_hotplug_handle_enable(void)
+{
+	int ret = 0;
+
+	ret = rte_dev_sigbus_handler_register();
+	if (ret < 0)
+		RTE_LOG(ERR, EAL, "fail to register sigbus handler for devices.\n");
+
+	hotplug_handle = true;
+
+	return ret;
+}
+
+int
+rte_dev_hotplug_handle_disable(void)
+{
+	int ret = 0;
+
+	ret = rte_dev_sigbus_handler_unregister();
+	if (ret < 0)
+		RTE_LOG(ERR, EAL, "fail to unregister sigbus handler for devices.\n");
+
+	hotplug_handle = false;
+
+	return ret;
+}
diff --git a/lib/librte_eal/rte_eal_version.map b/lib/librte_eal/rte_eal_version.map
index 344a43d..996e709 100644
--- a/lib/librte_eal/rte_eal_version.map
+++ b/lib/librte_eal/rte_eal_version.map
@@ -274,6 +274,8 @@ EXPERIMENTAL {
 	rte_dev_event_callback_unregister;
 	rte_dev_event_monitor_start;
 	rte_dev_event_monitor_stop;
+	rte_dev_hotplug_handle_enable;
+	rte_dev_hotplug_handle_disable;
 	rte_dev_iterator_init;
 	rte_dev_iterator_next;
 	rte_devargs_add;
-- 
2.7.4