Let's a concept of "rate limiting" to event sources: if specific event
sources fire too often in some time interval temporarily take them
offline, and take them back online once the interval passed.
This is a simple scheme of avoiding starvation of event sources if some
event source fires too often.
This introduces the new conceptual states of "offline" and "online" for
event sources: an event source is "online" only when enabled *and* not
ratelimited, and offline in all other cases. An event source that is
online hence has its fds registered in the epoll, its signals in the
signalfd and so on.
So far we used these fields to organize the earliest/latest timer event
priority queue. In a follow-up commit we want to introduce ratelimiting
to event sources, at which point we want any kind of event source to be
able to trigger time wakeups, and hence they all need to be included in
the earliest/latest prioqs. Thus, in preparation let's make this
generic.
No change in behaviour, just some shifting around of struct members from
the type-specific to the generic part.
sd_event_prepare() invokes callbacks that might drop the last user ref
on our event loop. Let's make sure we keep an explicit ref around it, so
that we won't end up with an invalid pointer. Similar in sd_event_run().
Basically, any function that is publically callable that might end up
invoking callbacks should ref the relevant objects to be protected
against callbacks destroying these objects while we still want to access
them. We did this correctly in sd_event_dispatch() and sd_event_loop(),
but these are not the only ones which are callable from the outside.
Commit 428a9f6f1d freed u->pids which is
problematic since the references to this unit in m->watch_pids were no more
removed when the unit was freed.
This patch makes sure to clean all this refs up before freeing u->pids by
calling unit_unwatch_all_pids().
This reverts the gist of da1921a5c3 and
0d9fca76bb (for ppc).
Quoting #17559:
> libseccomp 2.5 added socket syscall multiplexing on ppc64(el):
> https://github.com/seccomp/libseccomp/pull/229
>
> Like with i386, s390 and s390x this breaks socket argument filtering, so
> RestrictAddressFamilies doesn't work.
>
> This causes the unit test to fail:
> /* test_restrict_address_families */
> Operating on architecture: ppc
> Failed to install socket family rules for architecture ppc, skipping: Operation canceled
> Operating on architecture: ppc64
> Failed to add socket() rule for architecture ppc64, skipping: Invalid argument
> Operating on architecture: ppc64-le
> Failed to add socket() rule for architecture ppc64-le, skipping: Invalid argument
> Assertion 'fd < 0' failed at src/test/test-seccomp.c:424, function test_restrict_address_families(). Aborting.
>
> The socket filters can't be added so `socket(AF_UNIX, SOCK_DGRAM, 0);` still
> works, triggering the assertion.
Fixes#17559.
This test assumes capability_list_length() is an invalid cap number,
but that isn't true if the running kernel supports more caps than we were
compiled with, which results in the test failing.
Instead use cap_last_cap() + 1.
If cap_last_cap() is 63, there are no more 'invalid' cap numbers to test with,
so the invalid cap number test part is skipped.
In many cases the tables are largely the same, hence define a common set
of macros to generate the common parts.
This adds in a couple of missing specifiers here and there, so is more
thant just refactoring: it actually fixes accidental omissions.
Note that some entries that look like they could be unified under these
macros can't really be unified, since they are slightly different. For
example in the DNSSD service logic we want to use the DNSSD hostname for
%H rather than the unmodified kernel one.
If /sys/class/OOO node is created and destroyed during booting (kernle driver initialization fails),
systemd-udev-trigger.service fails due to race condition.
***** race condition ***********************************************************************************
1. kernel driver create /sys/class/OOO
2. systemd-udev-trigger.service execues "/usr/bin/udevadm trigger --type=devices --action=add"
3. device_enumerator_scan_devices() => enumerator_scan_devices_all() => enumerator_scan_dir("class") =>
opendir("/sys/class") and iterate all subdirs ==> enumerator_scan_dir_and_add_devices("/sys/class/OOO")
4. kernel driver fails and destroy /sys/class/OOO
5. enumerator_scan_dir_and_add_devices("/sys/class/OOO") fails in opendir("/sys/class/OOO")
6. "systemd-udev-trigger.service" fails
7. udev coldplug fails and some device units not ready
8. mount units asociated with device units fail
9. local-fs.target fails
10. enters emergency mode
********************************************************************************************************
***** status of systemd-udev-trigger.service unit ******************************************************
$ systemctl status systemd-udev-trigger.service
systemd-udev-trigger.service - udev Coldplug all Devices
Loaded: loaded (/usr/lib/systemd/system/systemd-udev-trigger.service; static; vendor preset: enabled)
Active: failed (Result: exit-code) since Thu 2020-01-02 13:16:54 KST; 22min ago
Docs: man:udev(7)
man:systemd-udevd.service(8)
Process: 2162 ExecStart=/usr/bin/udevadm trigger --type=subsystems --action=add (code=exited, status=0/SUCCESS)
Process: 2554 ExecStart=/usr/bin/udevadm trigger --type=devices --action=add (code=exited, status=1/FAILURE)
Main PID: 2554 (code=exited, status=1/FAILURE)
Jan 02 13:16:54 localhost udevadm[2554]: Failed to scan devices: No such file or directory
Jan 02 13:16:54 localhost systemd[1]: systemd-udev-trigger.service: Main process exited, code=exited, status=1/FAILURE
Jan 02 13:16:54 localhost systemd[1]: systemd-udev-trigger.service: Failed with result 'exit-code'.
Jan 02 13:16:54 localhost systemd[1]: Failed to start udev Coldplug all Devices.
*******************************************************************************************************
***** journal log with Environment=SYSTEMD_LOG_LEVEL=debug in systemd-udev-trigger.service ***********
Jan 01 21:57:20 localhost udevadm[2039]: sd-device-enumerator: Scanning /sys/bus
Jan 01 21:57:20 localhost udevadm[2522]: sd-device-enumerator: Scan all dirs
Jan 01 21:57:20 localhost udevadm[2522]: sd-device-enumerator: Scanning /sys/bus
Jan 01 21:57:21 localhost udevadm[2522]: sd-device-enumerator: Scanning /sys/class
Jan 01 21:57:21 localhost udevadm[2522]: sd-device-enumerator: Failed to scan /sys/class: No such file or directory
Jan 01 21:57:21 localhost udevadm[2522]: Failed to scan devices: No such file or directory
*******************************************************************************************************
