Fix setting flag in vm_area_struct for Kernel 6.3
See merge request etherlab.org/ethercat!67
(cherry picked from commit 04f202a39c)
27db882d Fix setting flag in vm_area_struct for Kernel 6.3
In upstream commit c9874d3ffeaf (termios: start unifying non-UAPI
parts of asm/termios.h), the INIT_C_CC definition was moved to a new
header, termios_internal.h. So we must include that header to get that
macro, but conditionally, since the header does not exist in older
kernels.
Manually maintaining the table of contents relies on how HTML fragments
are generated, it is prone to errors (infact it is already out of sync)
and just plain boring.
Unfortunately there is no common agreement on all markdown flavours on
how the table of contents must be implemented. Here the `[[_TOC_]]` tag
has been used because it is supported by both GitLab and GitHub:
https://gitlab.com/gitlab-org/gitlab/-/issues/21901
Introduce a new lock for synchronization of the master->domains list, and use
that instead of the big master_sem lock, improving real-time performance of
fx. ecrt_domain_process() when EoE thread is being shut down (or other
use-cases where master_sem is held for extended periods).
The following locking order is used:
* master->master_sem
* master->domains_lock
* master->io_sem
* domain->datagram_pairs_lock
Meaning that it is allowed to take domains_lock while holding master_sem, and
it is allowed to hold domains_lock while locking io_sem and
datagram_pairs_lock.
[RV: For now, the lockdep_assert_held() annotations are commented out,
since they don't compile with CONFIG_PROVE_LOCKING and (the default)
--disable-rtmutex.]
While domain->datagram_pairs was previously partly protected by the
master->master_sem lock (it was not done consistently though), the fix
to protection of master->datagram_queue made it even worse.
This change adds protection of domain->datagram_pairs using a new lock
dedicated to this. The domain->datagram_pairs_lock is acquired in the actual
functions accessing the domain->datagram_pairs, and this currently means that
it is acquired both in situations where master->master_sem is held and in
situations where master->io_sem is held.
With this, we should have in place so that master->io_sem is always held when
accessing master->datagram_queue.
Note, the use of master->master_sem in ec_ioctl_send() and
ec_ioctl_receive() were wrong (introduced in commit cef602586c). The
only thing needing to be synchronized there is the access to
master->datagram_queue, which is protected by master->io_sem.
This corresponds roughly to the fixes for stable-1.5 that are seen in
https://gitlab.com/etherlab.org/ethercat/-/merge_requests/36 .
In order to ensure proper use of locking, the purpose of each mutex/semaphore
must be clear and documented.
This is my best guess. The master->io_sem has a simple purpose, synchronizing
access to the master->datagram_queue list structure.
When converting to the ec_lock_t abstraction, these were missed,
making building with --enable-rtmutex broken.
Fixes: 9955855f7e (Applied 0016-If-enable-rtmutex-use-rtmutexes-instead-of-semaphore.patch)
- The unmodified upstream iproute2 package installs the ip utility in
/sbin. That is also where it thus ends up with for example Yocto
builds.
- Debian/Ubuntu installs it in /bin (and I assume that's how this came
to be), but their packaging logic provides a symlink /sbin/ip ->
/bin/ip .
- ArchLinux seems to install it in both places (as hardlinks).
- CentOS only has /sbin/ip.
- Fedora only has /sbin/ip.
So /sbin/ip should work everywhere, whereas /bin/ip does not.
This flag specifies that the file descriptor should be closed when an
exec function is invoked. When a file descriptor is allocated (as with
open or dup), O_CLOEXEC bit is initially cleared on the new file
descriptor, meaning that descriptor will survive into the new program
after exec. Setting O_CLOEXEC avoid this survival of the desciptor in
the new program. And setting it at open() time is the only race-free
way to avoid accidentally leaking the fd via other threads that
concurrently do fork()+exec() (or similar, e.g. posix_spawn).
alloc_tty_driver was deprecated by tty_alloc_driver in commit 7f0bc6a68ed9
(TTY: pass flags to alloc_tty_driver) in 2012 but first in kernel
v5.15 it has been dropped (56ec5880a28e). Switch to tty_alloc_driver
when using kernels >= v5.15
As of v5.15, the put_tty_driver alias has been dropped in favor of
directly calling tty_driver_kref_put (9f90a4ddef4e). Switch to
tty_driver_kref_put when using kernels >= v5.15
As from v5.14 the write_room (03b3b1a2405c) and
chars_in_buffer (fff4ef17a940) methods' return type changed from int
to unsigned int in struct tty_operations. This has impact on
ec_tty_write_room() and ec_tty_chars_in_buffer().
Florian Pose
Nicola Fontana
Andreas Stewering-Bone
Rasmus Villemoes
Jeppe Odgaard
Esben Haabendal
Per Noergaard Christensen
Per Noergaard Christensen