Hi Jeff,
>
> The mechanism can initially register the sigbus handler after the device
> event monitor is enabled. When a sigbus event is captured, it will check
> the failure address and accordingly handle the memory failure of the
> corresponding device by invoke the hot-unplug handler. It could prevent
> the application from crashing when a device is hot-unplugged.
>
> By this patch, users could call below new added APIs to enable/disable
> the device hotplug handle mechanism. Note that it just implement the
> hot-unplug handler in these functions, the other handler of hotplug, such
> as handler for hotplug binding, could be add in the future if need:
> - rte_dev_hotplug_handle_enable
> - rte_dev_hotplug_handle_disable
>
> Signed-off-by: Jeff Guo <jia....@intel.com>
> Acked-by: Shaopeng He <shaopeng...@intel.com>
> ---
> v11->v10:
> change some words and change the invoked func name.
> add experimental tag
> ---
> 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 | 162
> +++++++++++++++++++++++++++++++-
> lib/librte_eal/rte_eal_version.map | 2 +
> 6 files changed, 234 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..fe0e60f 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 hot-unplug handle mechanism.**
> +
> + ``rte_dev_hotplug_handle_enable`` and ``rte_dev_hotplug_handle_disable``
> are
> + for enabling or disabling hotplug handle mechanism.
> +
>
> API Changes
> -----------
> diff --git a/lib/librte_eal/bsdapp/eal/eal_dev.c
> b/lib/librte_eal/bsdapp/eal/eal_dev.c
> index 1c6c51b..255d611 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_experimental
> +rte_dev_hotplug_handle_enable(void)
> +{
> + RTE_LOG(ERR, EAL, "Device event is not supported for FreeBSD\n");
> + return -1;
> +}
> +
> +int __rte_experimental
> +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 a2d1528..637f20d 100644
> --- a/lib/librte_eal/common/eal_private.h
> +++ b/lib/librte_eal/common/eal_private.h
> @@ -317,4 +317,30 @@ 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 handler.
> + *
> + * @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 handler.
> + *
> + * @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..14b18d8 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 +16,32 @@
> #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 hot-unplug failure handling. If it try to access bus
> or
> + * device, such as handle sigbus on bus or handle memory failure for device
> + * just need to 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 +52,49 @@ 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 hot-unplug, "
> + "(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 hot-unplug!\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 +209,9 @@ 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 +236,43 @@ 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->hot_unplug_handler(dev);
> + rte_spinlock_unlock(&failure_handle_lock);
> + if (ret) {
> + RTE_LOG(ERR, EAL, "Can not handle hot-unplug "
> + "for device (%s)\n", dev->name);
> + return;
> + }
> + }
> dev_callback_process(uevent.devname, uevent.type);
> + }
> }
>
> int __rte_experimental
> @@ -220,5 +320,65 @@ rte_dev_event_monitor_stop(void)
> close(intr_handle.fd);
> intr_handle.fd = -1;
> monitor_started = false;
> +
> return 0;
> }
> +
> +int __rte_experimental
> +rte_dev_sigbus_handler_register(void)
> +{
> + sigset_t mask;
> + struct sigaction action;
> +
> + rte_errno = 0;
> +
Shouldn't you call sigaction only if sigbus_need_recover == 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_experimental
> +rte_dev_sigbus_handler_unregister(void)
> +{
> + rte_errno = 0;
> + sigbus_need_recover = 1;
Hmm, why to set sugbus_need_recover to 1 here?
If user called rte_dev_sigbus_handler_register() before, and it was successful,
it already would be 1.
In other cases, you probably don't have to do anything.
Konstantin
> +
> + sigbus_action_recover();
> +
> + return rte_errno;
> +}
> +
> +int __rte_experimental
> +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_experimental
> +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 73282bb..a3255aa 100644
> --- a/lib/librte_eal/rte_eal_version.map
> +++ b/lib/librte_eal/rte_eal_version.map
> @@ -281,6 +281,8 @@ 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
