[dpdk-dev] [PATCH V20 2/4] eal: add failure handler mechanism for hot plug

[Zhang, Qi Z]

Hi Jeff

> -----Original Message-----
> From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Jeff Guo
> Sent: Wednesday, April 18, 2018 9:38 PM
> To: stephen at networkplumber.org; Richardson, Bruce
> <bruce.richardson at intel.com>; Yigit, Ferruh <ferruh.yigit at intel.com>;
> Ananyev, Konstantin <konstantin.ananyev 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; Guo,
> Jia <jia.guo at intel.com>; Zhang, Helin <helin.zhang at intel.com>
> Subject: [dpdk-dev] [PATCH V20 2/4] eal: add failure handler mechanism for
> hot plug
> 
> 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>
> ---
> v20->v19:
> refine the logic of remapping for multiple device.
> ---
>  doc/guides/rel_notes/release_18_05.rst  |   6 ++
>  lib/librte_eal/common/include/rte_dev.h |  11 +++
>  lib/librte_eal/linuxapp/eal/eal_dev.c   | 124
> +++++++++++++++++++++++++++++++-
>  lib/librte_eal/rte_eal_version.map      |   1 +
>  4 files changed, 141 insertions(+), 1 deletion(-)
> 
> diff --git a/doc/guides/rel_notes/release_18_05.rst
> b/doc/guides/rel_notes/release_18_05.rst
> index a018ef5..a4ea9af 100644
> --- a/doc/guides/rel_notes/release_18_05.rst
> +++ b/doc/guides/rel_notes/release_18_05.rst
> @@ -70,6 +70,12 @@ New Features
> 
>    Linux uevent is supported as backend of this device event notification
> framework.
> 
> +* **Added hot plug failure handler.**
> +
> +  Added a failure handler machenism to handle hot unplug device.
> +
> +  * ``rte_dev_handle_hot_unplug`` for handle hot unplug device failure.
> +
> 
>  API Changes
>  -----------
> diff --git a/lib/librte_eal/common/include/rte_dev.h
> b/lib/librte_eal/common/include/rte_dev.h
> index 0955e9a..9933131 100644
> --- a/lib/librte_eal/common/include/rte_dev.h
> +++ b/lib/librte_eal/common/include/rte_dev.h
> @@ -360,4 +360,15 @@ 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
> + *
> + * It can be used to handle the device signal bus error. when signal
> +bus error
> + * occur, the handler would check the failure address to find the
> +corresponding
> + * device and remap the memory resource of the device, that would
> +guaranty
> + * the system not crash when the device be hot unplug.
> + */
> +void __rte_experimental
> +rte_dev_handle_hot_unplug(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 9478a39..33e7026 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>
> 
> @@ -13,12 +15,16 @@
>  #include <rte_malloc.h>
>  #include <rte_interrupts.h>
>  #include <rte_alarm.h>
> +#include <rte_bus.h>
> +#include <rte_eal.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
> 
> @@ -33,6 +39,68 @@ 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,
> +					"It cannot handle hot unplug "
> +					"for device (%s) "
> +					"on the bus.\n ",
> +					dev->name);
> +			}
> +		}
> +	} 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,
> +						"It cannot handle hot unplug "
> +						"for the device "
> +						"on the bus.\n ");
> +				}
> +			}
> +		}
> +	}
> +	return ret;
> +}
> +
> +static void sigbus_handler(int signum __rte_unused, siginfo_t *info,
> +				void *ctx __rte_unused)
> +{
> +	int ret;
> +
> +	RTE_LOG(ERR, EAL, "SIGBUS error, fault address:%p\n", info->si_addr);
> +	ret = dev_uev_failure_process(NULL, info->si_addr);
> +	if (!ret)
> +		RTE_LOG(DEBUG, EAL,
> +			"SIGBUS error is because of 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)
>  {
>  	struct sockaddr_nl addr;
> @@ -146,6 +214,9 @@ 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);
> @@ -170,8 +241,41 @@ 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;
> +			}
> +			ret = dev_uev_failure_process(dev, NULL);
> +			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
> @@ -216,8 +320,26 @@ rte_dev_event_monitor_stop(void)
>  		return ret;
>  	}
> 
> +	/* recover sigbus. */
> +	sigaction(SIGBUS, NULL, NULL);
> +
>  	close(intr_handle.fd);
>  	intr_handle.fd = -1;
>  	monitor_started = false;
> +
>  	return 0;
>  }
> +
> +void __rte_experimental
> +rte_dev_handle_hot_unplug(void)
> +{
> +	struct sigaction act;
> +
> +	/* set sigbus handler for hotplug. */
> +	memset(&act, 0x00, sizeof(struct sigaction));
> +	act.sa_sigaction = sigbus_handler;
> +	sigemptyset(&act.sa_mask);
> +	sigaddset(&act.sa_mask, SIGBUS);
> +	act.sa_flags = SA_SIGINFO;
> +	sigaction(SIGBUS, &act, NULL);
> +}

Not sure if it's necessary to expose this API, 
it can be invoked in rte_dev_event_monitor_start, 
since register a sigbus handler looks like an init step when user device to enable hotplug

Regards
Qi

> diff --git a/lib/librte_eal/rte_eal_version.map
> b/lib/librte_eal/rte_eal_version.map
> index d02d80b..39a0213 100644
> --- a/lib/librte_eal/rte_eal_version.map
> +++ b/lib/librte_eal/rte_eal_version.map
> @@ -217,6 +217,7 @@ EXPERIMENTAL {
>  	rte_dev_event_callback_unregister;
>  	rte_dev_event_monitor_start;
>  	rte_dev_event_monitor_stop;
> +	rte_dev_handle_hot_unplug;
>  	rte_eal_cleanup;
>  	rte_eal_devargs_insert;
>  	rte_eal_devargs_parse;
> --
> 2.7.4