diff options
| author | Breno Leitao <leitao@debian.org> | 2026-08-05 07:52:36 -0700 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2026-08-10 11:47:20 -1000 |
| commit | a5bde5d8fde8a8cb28e59a672d5ddc5b9c1e7656 (patch) | |
| tree | 39f5b258386e1127d253d293194e9a2991bf3c34 /Documentation/ABI/README | |
| download | linux-stable-a5bde5d8fde8a8cb28e59a672d5ddc5b9c1e7656.tar.gz linux-stable-a5bde5d8fde8a8cb28e59a672d5ddc5b9c1e7656.zip | |
workqueue: skip the node_nr_active update for non-unbound workqueuesgrafted
apply_wqattrs_commit() updates node_nr_active->max unconditionally.
wq->node_nr_active[] is only allocated for unbound workqueues, so guard
the call before per-cpu workqueues start using this path.
No functional change: only unbound workqueues reach apply_wqattrs_*()
today.
Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'Documentation/ABI/README')
| -rw-r--r-- | Documentation/ABI/README | 98 |
1 files changed, 98 insertions, 0 deletions
diff --git a/Documentation/ABI/README b/Documentation/ABI/README new file mode 100644 index 000000000..315fffe1f --- /dev/null +++ b/Documentation/ABI/README @@ -0,0 +1,98 @@ +This part of the documentation inside Documentation/ABI directory +attempts to document the ABI between the Linux kernel and +userspace, and the relative stability of these interfaces. Due to the +everchanging nature of Linux, and the differing maturity levels, these +interfaces should be used by userspace programs in different ways. + +We have four different levels of ABI stability, as shown by the four +different subdirectories in this location. Interfaces may change levels +of stability according to the rules described below. + +The different levels of stability are: + + stable/ + This directory documents the interfaces that the developer has + defined to be stable. Userspace programs are free to use these + interfaces with no restrictions, and backward compatibility for + them will be guaranteed for at least 2 years. Most interfaces + (like syscalls) are expected to never change and always be + available. + + testing/ + This directory documents interfaces that are felt to be stable, + as the main development of this interface has been completed. + The interface can be changed to add new features, but the + current interface will not break by doing this, unless grave + errors or security problems are found in them. Userspace + programs can start to rely on these interfaces, but they must be + aware of changes that can occur before these interfaces move to + be marked stable. Programs that use these interfaces are + strongly encouraged to add their name to the description of + these interfaces, so that the kernel developers can easily + notify them if any changes occur (see the description of the + layout of the files below for details on how to do this.) + + obsolete/ + This directory documents interfaces that are still remaining in + the kernel, but are marked to be removed at some later point in + time. The description of the interface will document the reason + why it is obsolete and when it can be expected to be removed. + + removed/ + This directory contains a list of the old interfaces that have + been removed from the kernel. + +Every file in these directories will contain the following information: + +What: Short description of the interface +Date: Date created +KernelVersion: (Optional) Kernel version this feature first showed up in. + Note: git history often provides more accurate version + info, so this field may be omitted. +Contact: Primary contact for this interface (may be a mailing list) +Description: Long description of the interface and how to use it. +Users: All users of this interface who wish to be notified when + it changes. This is very important for interfaces in + the "testing" stage, so that kernel developers can work + with userspace developers to ensure that things do not + break in ways that are unacceptable. It is also + important to get feedback for these interfaces to make + sure they are working in a proper way and do not need to + be changed further. + + +Note: + The fields should be use a simple notation, compatible with ReST markup. + Also, the file **should not** have a top-level index, like:: + + === + foo + === + +How things move between levels: + +Interfaces in stable may move to obsolete, as long as the proper +notification is given. + +Interfaces may be removed from obsolete and the kernel as long as the +documented amount of time has gone by. + +Interfaces in the testing state can move to the stable state when the +developers feel they are finished. They cannot be removed from the +kernel tree without going through the obsolete state first. + +It's up to the developer to place their interfaces in the category they +wish for it to start out in. + + +Notable bits of non-ABI, which should not under any circumstances be considered +stable: + +- Kconfig. Userspace should not rely on the presence or absence of any + particular Kconfig symbol, in /proc/config.gz, in the copy of .config + commonly installed to /boot, or in any invocation of the kernel build + process. + +- Kernel-internal symbols. Do not rely on the presence, absence, location, or + type of any kernel symbol, either in System.map files or the kernel binary + itself. See Documentation/process/stable-api-nonsense.rst. |
