[dpdk-dev] [PATCH V4 6/9] eal: add failure handle mechanism for hot plug

Ananyev, Konstantin konstantin.ananyev at intel.com
Fri Jun 29 12:49:46 CEST 2018


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.guo at 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



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