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

[Ananyev, Konstantin]

> -----Original Message-----
> From: Guo, Jia
> Sent: Tuesday, May 8, 2018 3:57 PM
> To: Ananyev, Konstantin <konstantin.ananyev at intel.com>; stephen at networkplumber.org; Richardson, Bruce
> <bruce.richardson at intel.com>; Yigit, Ferruh <ferruh.yigit at intel.com>; gaetan.rivet at 6wind.com; Wu, Jingjing
> <jingjing.wu at intel.com>; thomas at monjalon.net; motih at mellanox.com; matan at mellanox.com; Van Haaren, Harry
> <harry.van.haaren at intel.com>; Tan, Jianfeng <jianfeng.tan at intel.com>
> Cc: jblunck at infradead.org; shreyansh.jain at nxp.com; dev at dpdk.org; Zhang, Helin <helin.zhang at intel.com>
> Subject: Re: [PATCH V21 2/4] eal: add failure handle mechanism for hot plug
> 
> 
> 
> 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?

I think application can have its own sigbus handler installed (same as we do).

> >> +}
> >> +
> >> +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.

Ok, but user can call device_detach() on his own, without waiting for failure to happen, right?


> 
> >> +			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