[dpdk-dev] [PATCH V21 2/4] eal: add failure handle mechanism for hot plug

Guo, Jia jia.guo at intel.com
Tue May 8 16:57:21 CEST 2018



On 5/4/2018 11:56 PM, Ananyev, Konstantin wrote:
> Hi Jeff,
>
>> This patch introduces a failure handler mechanism to handle device
>> hot unplug event. When device be hot plug out, the device resource
>> become invalid, if this resource is still be unexpected read/write,
>> system will crash. This patch let eal help application to handle
>> this fault, when sigbus error occur, check the failure address and
>> accordingly remap the invalid memory for the corresponding device,
>> that could guaranty the application not to be shut down when hot plug.
>>
>> Signed-off-by: Jeff Guo <jia.guo at intel.com>
>> ---
>> v21->v20:
>> sync failure hanlde to fix multiple process issue
>> ---
>>   lib/librte_eal/linuxapp/eal/eal_dev.c | 154 +++++++++++++++++++++++++++++++++-
>>   1 file changed, 153 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..3067f39 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 +16,27 @@
>>   #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 "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 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. */
>> @@ -34,6 +48,93 @@ enum eal_dev_event_subsystem {
>>   };
>>
>>   static int
>> +dev_uev_failure_process(struct rte_device *dev, void *dev_addr)
>> +{
>> +	struct rte_bus *bus;
>> +	int ret = 0;
>> +
>> +	if (!dev && !dev_addr) {
>> +		return -EINVAL;
>> +	} else if (dev) {
>> +		bus = rte_bus_find_by_device_name(dev->name);
>> +		if (bus->handle_hot_unplug) {
>> +			/**
>> +			 * call bus ops to handle hot unplug.
>> +			 */
>> +			ret = bus->handle_hot_unplug(dev, dev_addr);
>> +			if (ret) {
>> +				RTE_LOG(ERR, EAL,
>> +					"Cannot handle hot unplug "
>> +					"for device %s "
>> +					"on the bus %s.\n ",
>> +					dev->name, bus->name);
>> +			}
>> +		} else {
>> +			RTE_LOG(ERR, EAL,
>> +				"Not support handle hot unplug for bus %s!\n",
>> +				bus->name);
>> +			ret = -ENOTSUP;
>> +		}
>> +	} else {
>> +		TAILQ_FOREACH(bus, &rte_bus_list, next) {
>> +			if (bus->handle_hot_unplug) {
>> +				/**
>> +				 * call bus ops to handle hot unplug.
>> +				 */
>> +				ret = bus->handle_hot_unplug(dev, dev_addr);
>> +				if (ret)
>> +					RTE_LOG(ERR, EAL,
>> +						"Cannot handle hot unplug "
>> +						"for the device "
>> +						"on the bus %s!\n", bus->name);
>> +				else
>> +					break;
>> +			} else {
>> +				RTE_LOG(ERR, EAL,
>> +					"Not support handle hot unplug "
>> +					"for bus %s!\n", bus->name);
>> +				ret = -ENOTSUP;
>> +			}
>> +		}
>> +	}
>> +	return ret;
>> +}
>> +
>> +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 __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 = dev_uev_failure_process(NULL, info->si_addr);
>> +	rte_spinlock_unlock(&dev_failure_lock);
>> +	if (!ret)
>> +		RTE_LOG(DEBUG, EAL,
>> +			"Success to handle SIGBUS error for hot unplug!\n");
>> +	else
>> +		rte_exit(EXIT_FAILURE, "exit for SIGBUS error!");
> I still think we have to distinguish here 2 cases:
> 1) failure addr is not belong to any dpdk devices
> 2) failure addr does belong to dpdk device, but we fail to remap it.
>
> For 1) we probably need to call previous sigbus handler.
> For 2) we probably can only do exit().

i think the previous sigbus handler is just a exception of sigbus error 
and exit out of the process, so i think should use one way to handler 
1)+2) should be fine, do you agree with that? or you could find any 
chance to
call any other sigbus handler at this positoin?
>> +}
>> +
>> +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)
>>   {
>>   	struct sockaddr_nl addr;
>> @@ -147,6 +248,9 @@ 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 +275,50 @@ 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",
>> +					uevent.devname);
>> +				return;
>> +			}
>> +			dev = bus->find_device(NULL, cmp_dev_name,
>> +					       uevent.devname);
>> +			if (dev == NULL) {
>> +				RTE_LOG(ERR, EAL,
>> +					"Cannot find unplugged device (%s)\n",
>> +					uevent.devname);
>> +				return;
>> +			}
>> +			rte_spinlock_lock(&dev_failure_lock);
>> +			ret = dev_uev_failure_process(dev, NULL);
>> +			rte_spinlock_unlock(&dev_failure_lock);
> That's interrupt thread, right?
> I wonder could it happen that user will call device_detach() at the same moment?
> Konstantin

it is in interrupt thread, and user will call device_detach after failure process, you concern about twice or more device detach? i don't think is there any problem here.

>> +			if (ret) {
>> +				RTE_LOG(ERR, EAL, "Driver cannot remap the "
>> +					"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 +338,14 @@ 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;
>> +	sigbus_need_recover = !sigaction(SIGBUS, &action, &sigbus_action_old);
>> +
>>   	monitor_started = true;
>>
>>   	return 0;
>> @@ -217,8 +366,11 @@ rte_dev_event_monitor_stop(void)
>>   		return ret;
>>   	}
>>
>> +	sigbus_action_recover();
>> +
>>   	close(intr_handle.fd);
>>   	intr_handle.fd = -1;
>>   	monitor_started = false;
>> +
>>   	return 0;
>>   }
>> --
>> 2.7.4



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