Re: [PATCH] multipath: enable getting uevents through libudev

[Zdenek Kabelac <zkabelac@redhat.com>]

Dne 4.4.2012 01:42, Benjamin Marzinski napsal(a):
> udev is removing support for RUN+="socket:..." rules. For now, I've kept
> all the existing uevent code, but I've added a new method for getting the
> uevent information using libudev that will be tried first.
>
> Signed-off-by: Benjamin Marzinski<bmarzins@redhat.com>
> ---
>   libmultipath/Makefile |    2
>   libmultipath/uevent.c |  151 ++++++++++++++++++++++++++++++++++++++++++++------
>   2 files changed, 134 insertions(+), 19 deletions(-)
>
> Index: multipath-tools-120123/libmultipath/Makefile
> ===================================================================
> --- multipath-tools-120123.orig/libmultipath/Makefile
> +++ multipath-tools-120123/libmultipath/Makefile
> @@ -7,7 +7,7 @@ include ../Makefile.inc
>   SONAME=0
>   DEVLIB = libmultipath.so
>   LIBS = $(DEVLIB).$(SONAME)
> -LIBDEPS = -lpthread -ldl -ldevmapper
> +LIBDEPS = -lpthread -ldl -ldevmapper -ludev
>
>   OBJS = memory.o parser.o vector.o devmapper.o callout.o \
>          hwtable.o blacklist.o util.o dmparser.o config.o \
> Index: multipath-tools-120123/libmultipath/uevent.c
> ===================================================================
> --- multipath-tools-120123.orig/libmultipath/uevent.c
> +++ multipath-tools-120123/libmultipath/uevent.c
> @@ -39,6 +39,7 @@
>   #include<pthread.h>
>   #include<limits.h>
>   #include<sys/mman.h>
> +#include<libudev.h>
>   #include<errno.h>
>
>   #include "memory.h"
> @@ -161,7 +162,7 @@ int uevent_dispatch(int (*uev_trigger)(s
>   	return 0;
>   }
>
> -int uevent_listen(void)
> +int failback_listen(void)
>   {
>   	int sock;
>   	struct sockaddr_nl snl;
> @@ -173,20 +174,6 @@ int uevent_listen(void)
>   	int rcvszsz = sizeof(rcvsz);
>   	unsigned int *prcvszsz = (unsigned int *)&rcvszsz;
>   	const int feature_on = 1;
> -
> -	/*
> -	 * Queue uevents for service by dedicated thread so that the uevent
> -	 * listening thread does not block on multipathd locks (vecs->lock)
> -	 * thereby not getting to empty the socket's receive buffer queue
> -	 * often enough.
> -	 */
> -	INIT_LIST_HEAD(&uevq);
> -
> -	pthread_mutex_init(uevq_lockp, NULL);
> -	pthread_cond_init(uev_condp, NULL);
> -
> -	pthread_cleanup_push(uevq_stop, NULL);
> -
>   	/*
>   	 * First check whether we have a udev socket
>   	 */
> @@ -382,13 +369,141 @@ int uevent_listen(void)
>
>   exit:
>   	close(sock);
> +	return 1;
> +}
>
> -	pthread_cleanup_pop(1);
> +int uevent_listen(void)
> +{
> +	int err;
> +	struct udev *udev = NULL;
> +	struct udev_monitor *monitor = NULL;
> +	int fd, socket_flags;
> +	int need_failback = 0;
> +	/*
> +	 * Queue uevents for service by dedicated thread so that the uevent
> +	 * listening thread does not block on multipathd locks (vecs->lock)
> +	 * thereby not getting to empty the socket's receive buffer queue
> +	 * often enough.
> +	 */
> +	INIT_LIST_HEAD(&uevq);
> +
> +	pthread_mutex_init(uevq_lockp, NULL);
> +	pthread_cond_init(uev_condp, NULL);
> +	pthread_cleanup_push(uevq_stop, NULL);
> +
> +	udev = udev_new();
> +	if (!udev) {
> +		condlog(2, "failed to create udev context");
> +		need_failback = 1;
> +		goto out;
> +	}
> +	monitor = udev_monitor_new_from_netlink(udev, "udev");
> +	if (!monitor) {
> +		condlog(2, "failed to create udev monitor");
> +		need_failback = 1;
> +		goto out;
> +	}
> +	if (udev_monitor_set_receive_buffer_size(monitor, 128 * 1024 * 1024))
> +		condlog(2, "failed to increase buffer size");
> +	fd = udev_monitor_get_fd(monitor);
> +	socket_flags = fcntl(fd, F_GETFL);
> +	if (socket_flags<  0) {
> +		condlog(2, "failed to get monitor socket flags : %s",
> +			strerror(errno));
> +		need_failback = 1;
> +		goto out;
> +	}
> +	if (fcntl(fd, F_SETFL, socket_flags&  ~O_NONBLOCK)<  0) {
> +		condlog(2, "failed to set monitor socket flags : %s",
> +			strerror(errno));
> +		need_failback = 1;
> +		goto out;
> +	}
> +	err = udev_monitor_filter_add_match_subsystem_devtype(monitor, "block",
> +							      NULL);
> +	if (err)
> +		condlog(2, "failed to create filter : %s\n", strerror(-err));
> +	err = udev_monitor_enable_receiving(monitor);
> +	if (err) {
> +		condlog(2, "failed to enable receiving : %s\n", strerror(-err));
> +		need_failback = 1;
> +		goto out;
> +	}
> +	while (1) {
> +		int i = 0;
> +		char *pos, *end;
> +		struct uevent *uev;
> +		struct udev_device *dev;
> +                struct udev_list_entry *list_entry;
> +
> +		dev = udev_monitor_receive_device(monitor);
> +		if (!dev) {
> +			condlog(0, "failed getting udev device");
> +			continue;
> +		}
>
> +		uev = alloc_uevent();
> +		if (!uev) {
> +			condlog(1, "lost uevent, oom");
> +			continue;
> +		}
> +		pos = uev->buffer;
> +		end = pos + HOTPLUG_BUFFER_SIZE + OBJECT_SIZE - 1;
> +		udev_list_entry_foreach(list_entry, udev_device_get_properties_list_entry(dev)) {
> +			const char *name, *value;
> +			int bytes;
> +
> +			name = udev_list_entry_get_name(list_entry);
> +			value = udev_list_entry_get_value(list_entry);
> +			bytes = snprintf(pos, end - pos, "%s=%s", name,

I'd recommend to validate all input going from libudev agains NULL pointers:

(i.e. look at https://bugzilla.redhat.com/show_bug.cgi?id=809576)

Zdenek