70 lines
3.4 KiB
Diff
70 lines
3.4 KiB
Diff
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From bf9d233f781f27841be6638ee745e9c80bda5f4d Mon Sep 17 00:00:00 2001
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From: Kay Sievers <kay@vrfy.org>
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Date: Tue, 13 Nov 2012 02:05:06 +0100
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Subject: [PATCH] udev: properly handle symlink removal by 'change' event
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If a 'change' event is supposed to remove created symlinks, we create
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a new device structure from the sysfs device and fill it with the list
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of links, to compute the delta of the old and new list of links to apply.
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If the device is already 'remove'd by the kernel though, udev fails to
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create the device structure, so the links are not removed properly.
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> From: Neil Brown <nfbrown@suse.com>
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> Date: Thu, 8 Nov 2012 10:39:06 +0100
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> Subject: [PATCH] If a 'change' event does not get handled by udev until
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> after the device has subsequently disappeared, udev mis-handles
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> it. This can happen with 'md' devices which emit a change
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> event and then a remove event when they are stopped. It is
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> normally only noticed if udev is very busy (lots of arrays
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> being stopped at once) or the machine is otherwise loaded
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> and reponding slowly.
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>
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> There are two problems.
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>
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> 1/ udev_device_new_from_syspath() will refuse to create the device
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> structure if the device does not exist in /sys, and particularly if
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> the uevent file does not exist.
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> If a 'db' file does exist, that is sufficient evidence that the device
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> is genuine and should be created. Equally if we have just received an
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> event from the kernel about the device, it must be real.
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>
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> This patch just disabled the test for the 'uevent' file, it doesn't
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> try imposing any other tests - it isn't clear that they are really
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> needed.
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>
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> 2/ udev_event_execute_rules() calls udev_device_read_db() on a 'device'
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> structure that is largely uninitialised and in particular does not
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> have the 'subsystem' set. udev_device_read_db() needs the subsystem
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> so it tries to read the 'subsystem' symlink out of sysfs. If the
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> device is already deleted, this naturally fails.
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> udev_event_execute_rules() knows the subsystem (as it was in the
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> event message) so this patch simply sets the subsystem for the device
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> structure to be loaded to match the subsystem of the device structure
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> that is handling the event.
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>
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> With these two changes, deleted handling of change events will still
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> correctly remove any symlinks that are not needed any more.
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Use udev_device_new() instead of allowing udev_device_new_from_syspath()
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to proceed without a sysfs device.
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---
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src/udev/udev-event.c | 4 +++-
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1 files changed, 3 insertions(+), 1 deletions(-)
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Index: systemd-195/src/udev/udev-event.c
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===================================================================
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--- systemd-195.orig/src/udev/udev-event.c
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+++ systemd-195/src/udev/udev-event.c
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@@ -797,8 +797,10 @@ int udev_event_execute_rules(struct udev
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if (major(udev_device_get_devnum(dev)) != 0)
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udev_node_remove(dev);
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} else {
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- event->dev_db = udev_device_new_from_syspath(event->udev, udev_device_get_syspath(dev));
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+ event->dev_db = udev_device_new(event->udev);
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if (event->dev_db != NULL) {
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+ udev_device_set_syspath(event->dev_db, udev_device_get_syspath(dev));
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+ udev_device_set_subsystem(event->dev_db, udev_device_get_subsystem(dev));
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udev_device_read_db(event->dev_db, NULL);
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udev_device_set_info_loaded(event->dev_db);
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