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Old 04-04-2012, 11:12 AM
Zdenek Kabelac
 
Default multipath: enable getting uevents through libudev

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(mo nitor, "block",
+ NULL);
+ if (err)
+ condlog(2, "failed to create filter : %s
", strerror(-err));
+ err = udev_monitor_enable_receiving(monitor);
+ if (err) {
+ condlog(2, "failed to enable receiving : %s
", 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

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Old 04-09-2012, 08:18 PM
Benjamin Marzinski
 
Default multipath: enable getting uevents through libudev

On Wed, Apr 04, 2012 at 01:12:45PM +0200, Zdenek Kabelac wrote:
> 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(mo nitor, "block",
>> + NULL);
>> + if (err)
>> + condlog(2, "failed to create filter : %s
", strerror(-err));
>> + err = udev_monitor_enable_receiving(monitor);
>> + if (err) {
>> + condlog(2, "failed to enable receiving : %s
", 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)

Looking at the udev code and the Libudev reference manual, most of my
checking decisions seem reasonable. I do more checking that udevd and
udevadm do. But I suppose it doesn't hurt to do some more.

I don't see how, given my previous checking, udev_monitor_get_fd() could
fail, but that function can return a failure, and it's no pain to check it.

Also, udev_list_entry_get_name() and udev_list_entry_get_value() can
return NULL, although I don't think it's possible here given that I
check and have a reference on the device, udev_list_entry_foreach()
cannot return a NULL list_entry, and I'm looking at a list of properties
which AFAIK must have a value. None of the udev code checks for NULL
here itself. But again, there's no compelling reason not to check for
NULL.

I'll resend this patch with the additional checks.

-Ben

>
> Zdenek

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Old 04-10-2012, 04:01 AM
Benjamin Marzinski
 
Default multipath: enable getting uevents through libudev

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.

This version includes more error checking.

Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
---
libmultipath/Makefile | 2
libmultipath/uevent.c | 155 ++++++++++++++++++++++++++++++++++++++++++++------
2 files changed, 138 insertions(+), 19 deletions(-)

Index: multipath-tools-120403/libmultipath/Makefile
================================================== =================
--- multipath-tools-120403.orig/libmultipath/Makefile
+++ multipath-tools-120403/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-120403/libmultipath/uevent.c
================================================== =================
--- multipath-tools-120403.orig/libmultipath/uevent.c
+++ multipath-tools-120403/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 +369,145 @@ 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 = 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);
+
+ udev = udev_new();
+ if (!udev) {
+ condlog(2, "failed to create udev context");
+ goto out;
+ }
+ monitor = udev_monitor_new_from_netlink(udev, "udev");
+ if (!monitor) {
+ condlog(2, "failed to create udev monitor");
+ 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);
+ if (fd < 0) {
+ condlog(2, "failed to get monitor fd");
+ goto out;
+ }
+ socket_flags = fcntl(fd, F_GETFL);
+ if (socket_flags < 0) {
+ condlog(2, "failed to get monitor socket flags : %s",
+ strerror(errno));
+ goto out;
+ }
+ if (fcntl(fd, F_SETFL, socket_flags & ~O_NONBLOCK) < 0) {
+ condlog(2, "failed to set monitor socket flags : %s",
+ strerror(errno));
+ goto out;
+ }
+ err = udev_monitor_filter_add_match_subsystem_devtype(mo nitor, "block",
+ NULL);
+ if (err)
+ condlog(2, "failed to create filter : %s
", strerror(-err));
+ err = udev_monitor_enable_receiving(monitor);
+ if (err) {
+ condlog(2, "failed to enable receiving : %s
", strerror(-err));
+ 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);
+ if (!name)
+ name = "(null)";
+ value = udev_list_entry_get_value(list_entry);
+ if (!value)
+ value = "(null)";
+ bytes = snprintf(pos, end - pos, "%s=%s", name,
+ value);
+ if (pos + bytes >= end) {
+ condlog(2, "buffer overflow for uevent");
+ break;
+ }
+ uev->envp[i] = pos;
+ pos += bytes;
+ *pos = '';
+ pos++;
+ if (strcmp(name, "DEVPATH") == 0)
+ uev->devpath = uev->envp[i] + 8;
+ if (strcmp(name, "ACTION") == 0)
+ uev->action = uev->envp[i] + 7;
+ i++;
+ if (i == HOTPLUG_NUM_ENVP - 1)
+ break;
+ }
+ udev_device_unref(dev);
+ uev->envp[i] = NULL;
+
+ condlog(3, "uevent '%s' from '%s'", uev->action, uev->devpath);
+ uev->kernel = strrchr(uev->devpath, '/');
+ if (uev->kernel)
+ uev->kernel++;
+
+ /* print payload environment */
+ for (i = 0; uev->envp[i] != NULL; i++)
+ condlog(5, "%s", uev->envp[i]);
+
+ /*
+ * Queue uevent and poke service pthread.
+ */
+ pthread_mutex_lock(uevq_lockp);
+ list_add_tail(&uev->node, &uevq);
+ pthread_cond_signal(uev_condp);
+ pthread_mutex_unlock(uevq_lockp);
+ }
+ need_failback = 0;
+out:
+ if (monitor)
+ udev_monitor_unref(monitor);
+ if (udev)
+ udev_unref(udev);
+ if (need_failback)
+ err = failback_listen();
+ pthread_cleanup_pop(1);
pthread_mutex_destroy(uevq_lockp);
pthread_cond_destroy(uev_condp);
-
- return 1;
+ return err;
}

extern int

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