If the main daemon is not notified about a worker finishing an event
the refcounting of the worker struct will be wrong, and we will lose
track of the number of children we have to wait for.
This should not happen, but if it does we better complain loudly about
it. Worst case udev will wait for 30 seconsd at shutdown waiting for
nonexistent workers.
Remove some redundant logging, and reduce the log-level in most cases. The only
case that is really critical is if a worker failed while hanlding an event, so
keep that at error level.
udev uses inotify to implement a scheme where when the user closes
a writable device node, a change uevent is forcefully generated.
In the case of block devices, it actually requests a partition rescan.
This currently can't be synchronized with "udevadm settle", i.e. this
is not reliable in a script:
sfdisk --change-id /dev/sda 1 81
udevadm settle
mount /dev/sda1 /foo
The settle call doesn't synchronize there, so at the same time we try
to mount the device, udevd is busy removing the partition device nodes and
readding them again. The mount call often happens in that moment where the
partition node has been removed but not readded yet.
This exact issue was fixed long ago:
http://git.kernel.org/cgit/linux/hotplug/udev.git/commit/?id=bb38678e3ccc02bcd970ccde3d8166a40edf92d3
but that fix is no longer valid now that sequence numbers are no longer
used.
Fix this by forcing another mainloop iteration after handling inotify events
before unblocking settle. If the inotify event caused us to generate a
"change" event, we'll pick that up in the following loop iteration, before
we reach the end of the loop where we respond to settle's control message,
unblocking it.
The information in the db is stale, so it does not make sense to
expose it any longer. Also, don't drop the kernel event, but simply
pass it on to userspace without ammending it.
This essentially replaces
open("/run/udev/queue", O_WRONLY|O_CREAT|O_CLOEXEC|O_TRUNC|O_NOFOLLOW, 0444)
with
open("/run/udev/queue", O_WRONLY|O_CREAT|O_CLOEXEC|O_NOCTTY, 0644),
which is ok for our purposes.
The udev-settle guarantees that udevd is no longer processing any of the
events casued by udev-trigger. The way this works is that it sends a
synchronous PING to udevd after udev-trigger has ran, and when that returns
it knows that udevd has started processing the events from udev-trigger.
udev-settle will then wait for the event queue to empty before returning.
However, there was a race here, as we would only update the /run state at
the beginning of the event loop, before reading out new events and before
processing the ping.
That means that if the first uevent arrived in the same event-loop iteration
as the PING, we would return the ping before updating the queue state in /run
(which would happen on the next iteration).
The race window here is tiny (as the /run state would probably get updated
before udev-settle got a chance to read /run), but still a possibility.
Fix the problem by updating the /run state as the last step before returning
the PING.
We must still update it at the beginning of the loop as well, otherwise we
risk being stuck in poll() with a stale state in /run.
Reported-by: Daniel Drake <drake@endlessm.com>
This patch removes includes that are not used. The removals were found with
include-what-you-use which checks if any of the symbols from a header is
in use.
include-what-you-use automatically does this and it makes finding
unnecessary harder to spot. The only content of poll.h is a include
of sys/poll.h so should be harmless.
If the format string contains %m, clearly errno must have a meaningful
value, so we might as well use log_*_errno to have ERRNO= logged.
Using:
find . -name '*.[ch]' | xargs sed -r -i -e \
's/log_(debug|info|notice|warning|error|emergency)\((".*%m.*")/log_\1_errno(errno, \2/'
Plus some whitespace, linewrap, and indent adjustments.
As a followup to 086891e5c1 "log: add an "error" parameter to all
low-level logging calls and intrdouce log_error_errno() as log calls
that take error numbers", use sed to convert the simple cases to use
the new macros:
find . -name '*.[ch]' | xargs sed -r -i -e \
's/log_(debug|info|notice|warning|error|emergency)\("(.*)%s"(.*), strerror\(-([a-zA-Z_]+)\)\);/log_\1_errno(-\4, "\2%m"\3);/'
Multi-line log_*() invocations are not covered.
And we also should add log_unit_*_errno().
Processes expecting static nodes to have the right permissions may order themselves after systemd-udevd.service,
make sure that actually guarantees what is expected.
