Hi Jeff,
>
> This patch introduces a failure handler mechanism to handle device
> hot plug removal event.
>
> First register sigbus handler, once sigbus error be captured, will
> check the failure address and accordingly remap the invalid memory
> for the corresponding device. Bese on this mechanism, it could
> guaranty the application not to be crash when hot unplug devices.
>
> Signed-off-by: Jeff Guo <jia....@intel.com>
> ---
> v4->v3:
> split patches to be small and clear.
> ---
> lib/librte_eal/linuxapp/eal/eal_dev.c | 88
> ++++++++++++++++++++++++++++++++++-
> 1 file changed, 87 insertions(+), 1 deletion(-)
>
> diff --git a/lib/librte_eal/linuxapp/eal/eal_dev.c
> b/lib/librte_eal/linuxapp/eal/eal_dev.c
> index 1cf6aeb..c9dddab 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 +16,24 @@
> #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;
>
> +extern struct rte_bus_list rte_bus_list;
> +
> #define EAL_UEV_MSG_LEN 4096
> #define EAL_UEV_MSG_ELEM_LEN 128
>
> +/* spinlock for device failure process */
> +static rte_spinlock_t dev_failure_lock = RTE_SPINLOCK_INITIALIZER;
> +
> static void dev_uev_handler(__rte_unused void *param);
>
> /* identify the system layer which reports this event. */
> @@ -33,6 +44,34 @@ enum eal_dev_event_subsystem {
> EAL_DEV_EVENT_SUBSYSTEM_MAX
> };
>
> +static void sigbus_handler(int signum __rte_unused, siginfo_t *info,
> + void *ctx __rte_unused)
> +{
> + int ret;
> +
> + RTE_LOG(DEBUG, EAL, "Thread[%d] catch SIGBUS, fault address:%p\n",
> + (int)pthread_self(), info->si_addr);
> +
> + rte_spinlock_lock(&dev_failure_lock);
> + ret = rte_bus_sigbus_handler(info->si_addr);
> + rte_spinlock_unlock(&dev_failure_lock);
> + if (!ret)
> + RTE_LOG(INFO, EAL,
> + "Success to handle SIGBUS error for hotplug!\n");
> + else
> + rte_exit(EXIT_FAILURE,
> + "A generic SIGBUS error, (rte_errno: %s)!",
> + strerror(rte_errno));
> +}
As I said in comments for previous versions:
I think we need to distinguish why do we fail -
1) address doesn't belong to any device,
2) we failed to remap
For 1) we probably need to call previous sigbus handler.
> +
> +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 +186,9 @@ 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);
> @@ -171,13 +213,48 @@ 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) {
> + 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;
> + }
> + rte_spinlock_lock(&dev_failure_lock);
> + ret = bus->hotplug_handler(dev);
> + rte_spinlock_unlock(&dev_failure_lock);
Ok, but this function is executed from interrupt thread, correct?
What would happen if user would do dev-detach() at the same time and dev would
not be valid anymore?
Shouldn't we have a lock (per bus?) that we would grab before find_device() and
release after hotplug_handler?
Though in that case we probably need to revisit other bus ops too.
> + 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
> rte_dev_event_monitor_start(void)
> {
> + sigset_t mask;
> + struct sigaction action;
> int ret;
>
> if (monitor_started)
> @@ -197,6 +274,14 @@ rte_dev_event_monitor_start(void)
> return -1;
> }
>
> + /* register sigbus handler */
> + sigemptyset(&mask);
> + sigaddset(&mask, SIGBUS);
> + action.sa_flags = SA_SIGINFO;
> + action.sa_mask = mask;
> + action.sa_sigaction = sigbus_handler;
> + sigaction(SIGBUS, &action, NULL);
> +
I still think we have to save (and restore at monitor_stop) previous sigbus
handler.
> monitor_started = true;
>
> return 0;
> @@ -220,5 +305,6 @@ rte_dev_event_monitor_stop(void)
> close(intr_handle.fd);
> intr_handle.fd = -1;
> monitor_started = false;
> +
> return 0;
> }
> --
> 2.7.4
