[libcamera-devel] [RFC PATCH] libcamera: device_enumerator: fix udev media graph loading dependency
Paul Elder
paul.elder at ideasonboard.com
Wed Aug 28 05:40:20 CEST 2019
When a MediaDevice is enumerated and populated by the
DeviceEnumeratorUdev, there is a possibility that the member device
nodes of the media graph would not be ready. The MediaDevice is still
passed up to the pipeline handler, where an attempt to access the device
nodes will fail in EPERM. This whole issue is especially likely to
happen when libcamera is run at system init time.
To fix this, we first split DeviceEnumerator::addDevice() into three
methods:
- createDevice() to simply create the MediaDevice
- (abstract method) populateMediaDevice() to populate the MediaDevice
- addDevice() to pass the MediaDevice up to the pipeline handler
DeviceEnumeratorSysfs calls these methods in succession, similar to what
it did before when they were all together as addDevice().
DeviceEnumeratorUdev additionally keeps a map of MediaDevices to a list
of pending device nodes (plus some other auxillary maps), and a simple
list of orphan device nodes. If a v4l device node is ready and there
does not exist any MediaDevice node for it, then it goes to the orphan
list, otherwise it is initialized and removed from the pending list of
the corresponding MediaDevice in the dependency map. When a MediaDevice
is populated via DeviceEnumeratorUdev::populateMediaDevice(), it first
checks the orphan list to see if the device node it needs is there,
otherwise it tries to initialize the device node and if it fails, then
it adds the device node it wants to its list in the dependency map.
This allows MediaDevices to be created and initialized properly with
udev when v4l device nodes in the media graph may not be ready when the
MediaDevice is populated.
Signed-off-by: Paul Elder <paul.elder at ideasonboard.com>
---
todos:
- add documentation
- better name for the maps
- better name for populateMediaDevice()
src/libcamera/device_enumerator.cpp | 27 +---
src/libcamera/device_enumerator_sysfs.cpp | 33 +++-
src/libcamera/device_enumerator_udev.cpp | 142 +++++++++++++++++-
src/libcamera/include/device_enumerator.h | 4 +-
.../include/device_enumerator_sysfs.h | 5 +-
.../include/device_enumerator_udev.h | 14 ++
6 files changed, 197 insertions(+), 28 deletions(-)
diff --git a/src/libcamera/device_enumerator.cpp b/src/libcamera/device_enumerator.cpp
index 60c918f..fd5a20c 100644
--- a/src/libcamera/device_enumerator.cpp
+++ b/src/libcamera/device_enumerator.cpp
@@ -204,7 +204,7 @@ DeviceEnumerator::~DeviceEnumerator()
*
* \return 0 on success or a negative error code otherwise
*/
-int DeviceEnumerator::addDevice(const std::string &deviceNode)
+std::shared_ptr<MediaDevice> DeviceEnumerator::createDevice(const std::string &deviceNode)
{
std::shared_ptr<MediaDevice> media = std::make_shared<MediaDevice>(deviceNode);
@@ -213,33 +213,22 @@ int DeviceEnumerator::addDevice(const std::string &deviceNode)
LOG(DeviceEnumerator, Info)
<< "Unable to populate media device " << deviceNode
<< " (" << strerror(-ret) << "), skipping";
- return ret;
+ return nullptr;
}
LOG(DeviceEnumerator, Debug)
<< "New media device \"" << media->driver()
<< "\" created from " << deviceNode;
- /* Associate entities to device node paths. */
- for (MediaEntity *entity : media->entities()) {
- if (entity->deviceMajor() == 0 && entity->deviceMinor() == 0)
- continue;
-
- std::string deviceNode = lookupDeviceNode(entity->deviceMajor(),
- entity->deviceMinor());
- if (deviceNode.empty())
- return -EINVAL;
-
- ret = entity->setDeviceNode(deviceNode);
- if (ret)
- return ret;
- }
+ return media;
+}
+int DeviceEnumerator::addDevice(std::shared_ptr<MediaDevice> media)
+{
LOG(DeviceEnumerator, Debug)
- << "Added device " << deviceNode << ": " << media->driver();
-
- devices_.push_back(std::move(media));
+ << "Added device " << media->deviceNode() << ": " << media->driver();
+ devices_.push_back(media);
return 0;
}
diff --git a/src/libcamera/device_enumerator_sysfs.cpp b/src/libcamera/device_enumerator_sysfs.cpp
index f3054d5..3b5bc90 100644
--- a/src/libcamera/device_enumerator_sysfs.cpp
+++ b/src/libcamera/device_enumerator_sysfs.cpp
@@ -71,7 +71,18 @@ int DeviceEnumeratorSysfs::enumerate()
continue;
}
- addDevice(devnode);
+ std::shared_ptr<MediaDevice> media = createDevice(devnode);
+ if (!media) {
+ closedir(dir);
+ return -ENODEV;
+ }
+
+ if (populateMediaDevice(media) < 0) {
+ closedir(dir);
+ return -ENODEV;
+ }
+
+ addDevice(media);
}
closedir(dir);
@@ -79,6 +90,26 @@ int DeviceEnumeratorSysfs::enumerate()
return 0;
}
+int DeviceEnumeratorSysfs::populateMediaDevice(std::shared_ptr<MediaDevice> media)
+{
+ /* Associate entities to device node paths. */
+ for (MediaEntity *entity : media->entities()) {
+ if (entity->deviceMajor() == 0 && entity->deviceMinor() == 0)
+ continue;
+
+ std::string deviceNode = lookupDeviceNode(entity->deviceMajor(),
+ entity->deviceMinor());
+ if (deviceNode.empty())
+ return -EINVAL;
+
+ int ret = entity->setDeviceNode(deviceNode);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+
std::string DeviceEnumeratorSysfs::lookupDeviceNode(int major, int minor)
{
std::string deviceNode;
diff --git a/src/libcamera/device_enumerator_udev.cpp b/src/libcamera/device_enumerator_udev.cpp
index 86f6ca1..ef9a31d 100644
--- a/src/libcamera/device_enumerator_udev.cpp
+++ b/src/libcamera/device_enumerator_udev.cpp
@@ -7,6 +7,10 @@
#include "device_enumerator_udev.h"
+#include <algorithm>
+#include <list>
+#include <map>
+
#include <fcntl.h>
#include <libudev.h>
#include <string.h>
@@ -57,6 +61,11 @@ int DeviceEnumeratorUdev::init()
if (ret < 0)
return ret;
+ ret = udev_monitor_filter_add_match_subsystem_devtype(monitor_, "video4linux",
+ nullptr);
+ if (ret < 0)
+ return ret;
+
return 0;
}
@@ -74,6 +83,14 @@ int DeviceEnumeratorUdev::enumerate()
if (ret < 0)
goto done;
+ ret = udev_enumerate_add_match_subsystem(udev_enum, "video4linux");
+ if (ret < 0)
+ goto done;
+
+ ret = udev_enumerate_add_match_is_initialized(udev_enum);
+ if (ret < 0)
+ goto done;
+
ret = udev_enumerate_scan_devices(udev_enum);
if (ret < 0)
goto done;
@@ -85,6 +102,7 @@ int DeviceEnumeratorUdev::enumerate()
udev_list_entry_foreach(ent, ents) {
struct udev_device *dev;
const char *devnode;
+ const char *subsystem;
const char *syspath = udev_list_entry_get_name(ent);
dev = udev_device_new_from_syspath(udev_, syspath);
@@ -96,16 +114,36 @@ int DeviceEnumeratorUdev::enumerate()
}
devnode = udev_device_get_devnode(dev);
- if (!devnode) {
- udev_device_unref(dev);
- ret = -ENODEV;
- goto done;
+ if (!devnode)
+ goto unref;
+
+ subsystem = udev_device_get_subsystem(dev);
+ if (!subsystem)
+ goto unref;
+
+ if (!strcmp(subsystem, "media")) {
+ std::shared_ptr<MediaDevice> media = createDevice(devnode);
+ if (!media)
+ goto unref;
+
+ ret = populateMediaDevice(media);
+ if (ret == 0)
+ addDevice(media);
+ } else if (!strcmp(subsystem, "video4linux")) {
+ addV4L2Device(udev_device_get_devnum(dev));
+ } else {
+ goto unref;
}
- addDevice(devnode);
+ udev_device_unref(dev);
+ continue;
+ unref:
udev_device_unref(dev);
+ ret = -ENODEV;
+ goto done;
}
+
done:
udev_enumerate_unref(udev_enum);
if (ret < 0)
@@ -122,6 +160,49 @@ done:
return 0;
}
+int DeviceEnumeratorUdev::populateMediaDevice(std::shared_ptr<MediaDevice> media)
+{
+ /* number of pending devnodes */
+ int count = 0;
+ int ret;
+
+ /* Associate entities to device node paths. */
+ for (MediaEntity *entity : media->entities()) {
+ if (entity->deviceMajor() == 0 && entity->deviceMinor() == 0)
+ continue;
+
+ std::string deviceNode = lookupDeviceNode(entity->deviceMajor(),
+ entity->deviceMinor());
+ dev_t devnum = makedev(entity->deviceMajor(),
+ entity->deviceMinor());
+
+ /* take device from orphan list first, if it is in the list */
+ if (std::find(orphans_.begin(), orphans_.end(), devnum) != orphans_.end()) {
+ if (deviceNode.empty())
+ return -EINVAL;
+
+ ret = entity->setDeviceNode(deviceNode);
+ if (ret)
+ return ret;
+
+ orphans_.remove(devnum);
+ continue;
+ }
+
+ if (deviceNode.empty() || (ret = ::access(deviceNode.c_str(), R_OK | W_OK)) < 0) {
+ map_[media].push_back(devnum);
+ revMap_[devnum] = media;
+ devnumToEntity_[devnum] = entity;
+ count++;
+ }
+
+ if (!ret)
+ entity->setDeviceNode(deviceNode);
+ }
+
+ return count;
+}
+
std::string DeviceEnumeratorUdev::lookupDeviceNode(int major, int minor)
{
struct udev_device *device;
@@ -143,17 +224,66 @@ std::string DeviceEnumeratorUdev::lookupDeviceNode(int major, int minor)
return deviceNode;
}
+// add V4L2 device to the media device if it exists, otherwise to the orphan list
+// if adding to media device, and it's the last one, then send up the media device
+int DeviceEnumeratorUdev::addV4L2Device(dev_t devnum)
+{
+ MediaEntity *entity = devnumToEntity_[devnum];
+ if (!entity) {
+ orphans_.push_back(devnum);
+ return 0;
+ }
+
+ std::string deviceNode = lookupDeviceNode(entity->deviceMajor(),
+ entity->deviceMinor());
+ if (deviceNode.empty())
+ return -EINVAL;
+
+ int ret = entity->setDeviceNode(deviceNode);
+ if (ret)
+ return ret;
+
+ std::shared_ptr<MediaDevice> media = revMap_[devnum];
+ map_[media].remove(devnum);
+ revMap_.erase(devnum);
+ devnumToEntity_.erase(devnum);
+
+ if (map_[media].empty())
+ addDevice(media);
+
+ return 0;
+}
+
void DeviceEnumeratorUdev::udevNotify(EventNotifier *notifier)
{
struct udev_device *dev = udev_monitor_receive_device(monitor_);
std::string action(udev_device_get_action(dev));
std::string deviceNode(udev_device_get_devnode(dev));
+ dev_t deviceNum(udev_device_get_devnum(dev));
LOG(DeviceEnumerator, Debug)
<< action << " device " << udev_device_get_devnode(dev);
if (action == "add") {
- addDevice(deviceNode);
+ const char *subsystem = udev_device_get_subsystem(dev);
+ if (!subsystem) {
+ udev_device_unref(dev);
+ return;
+ }
+
+ if (!strcmp(subsystem, "media")) {
+ std::shared_ptr<MediaDevice> media = createDevice(deviceNode);
+ if (!media) {
+ udev_device_unref(dev);
+ return;
+ }
+
+ int ret = populateMediaDevice(media);
+ if (ret == 0)
+ addDevice(media);
+ } else if (!strcmp(subsystem, "video4linux")) {
+ addV4L2Device(deviceNum);
+ }
} else if (action == "remove") {
removeDevice(deviceNode);
}
diff --git a/src/libcamera/include/device_enumerator.h b/src/libcamera/include/device_enumerator.h
index 02aec3b..4c3e500 100644
--- a/src/libcamera/include/device_enumerator.h
+++ b/src/libcamera/include/device_enumerator.h
@@ -44,12 +44,14 @@ public:
std::shared_ptr<MediaDevice> search(const DeviceMatch &dm);
protected:
- int addDevice(const std::string &deviceNode);
+ std::shared_ptr<MediaDevice> createDevice(const std::string &deviceNode);
+ int addDevice(std::shared_ptr<MediaDevice> media);
void removeDevice(const std::string &deviceNode);
private:
std::vector<std::shared_ptr<MediaDevice>> devices_;
+ virtual int populateMediaDevice(std::shared_ptr<MediaDevice>) = 0;
virtual std::string lookupDeviceNode(int major, int minor) = 0;
};
diff --git a/src/libcamera/include/device_enumerator_sysfs.h b/src/libcamera/include/device_enumerator_sysfs.h
index 8d3adc9..d14bbf8 100644
--- a/src/libcamera/include/device_enumerator_sysfs.h
+++ b/src/libcamera/include/device_enumerator_sysfs.h
@@ -9,6 +9,8 @@
#include <string>
+#include "media_device.h"
+
#include "device_enumerator.h"
namespace libcamera {
@@ -20,7 +22,8 @@ public:
int enumerate();
private:
- std::string lookupDeviceNode(int major, int minor);
+ int populateMediaDevice(std::shared_ptr<MediaDevice> media) final;
+ std::string lookupDeviceNode(int major, int minor) final;
};
} /* namespace libcamera */
diff --git a/src/libcamera/include/device_enumerator_udev.h b/src/libcamera/include/device_enumerator_udev.h
index 80f9372..b3bbcb0 100644
--- a/src/libcamera/include/device_enumerator_udev.h
+++ b/src/libcamera/include/device_enumerator_udev.h
@@ -7,8 +7,14 @@
#ifndef __LIBCAMERA_DEVICE_ENUMERATOR_UDEV_H__
#define __LIBCAMERA_DEVICE_ENUMERATOR_UDEV_H__
+#include <list>
+#include <map>
#include <string>
+#include <sys/sysmacros.h>
+
+#include "media_device.h"
+
#include "device_enumerator.h"
struct udev;
@@ -32,8 +38,16 @@ private:
struct udev_monitor *monitor_;
EventNotifier *notifier_;
+ std::map<std::shared_ptr<MediaDevice>, std::list<dev_t>> map_;
+ std::map<dev_t, std::shared_ptr<MediaDevice>> revMap_;
+ std::map<dev_t, MediaEntity *> devnumToEntity_;
+
+ std::list<dev_t> orphans_;
+
+ int populateMediaDevice(std::shared_ptr<MediaDevice> media) final;
std::string lookupDeviceNode(int major, int minor) final;
+ int addV4L2Device(dev_t devnum);
void udevNotify(EventNotifier *notifier);
};
--
2.20.1
More information about the libcamera-devel
mailing list