From a5bde5d8fde8a8cb28e59a672d5ddc5b9c1e7656 Mon Sep 17 00:00:00 2001 From: Breno Leitao Date: Wed, 5 Aug 2026 07:52:36 -0700 Subject: workqueue: skip the node_nr_active update for non-unbound workqueues 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 Signed-off-by: Tejun Heo --- Documentation/kbuild/headers_install.rst | 44 ++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) create mode 100644 Documentation/kbuild/headers_install.rst (limited to 'Documentation/kbuild/headers_install.rst') diff --git a/Documentation/kbuild/headers_install.rst b/Documentation/kbuild/headers_install.rst new file mode 100644 index 000000000..f6c6b74a6 --- /dev/null +++ b/Documentation/kbuild/headers_install.rst @@ -0,0 +1,44 @@ +============================================= +Exporting kernel headers for use by userspace +============================================= + +The "make headers_install" command exports the kernel's header files in a +form suitable for use by userspace programs. + +The linux kernel's exported header files describe the API for user space +programs attempting to use kernel services. These kernel header files are +used by the system's C library (such as glibc or uClibc) to define available +system calls, as well as constants and structures to be used with these +system calls. The C library's header files include the kernel header files +from the "linux" subdirectory. The system's libc headers are usually +installed at the default location /usr/include and the kernel headers in +subdirectories under that (most notably /usr/include/linux and +/usr/include/asm). + +Kernel headers are backwards compatible, but not forwards compatible. This +means that a program built against a C library using older kernel headers +should run on a newer kernel (although it may not have access to new +features), but a program built against newer kernel headers may not work on an +older kernel. + +The "make headers_install" command can be run in the top level directory of the +kernel source code (or using a standard out-of-tree build). It takes two +optional arguments:: + + make headers_install ARCH=i386 INSTALL_HDR_PATH=/usr + +ARCH indicates which architecture to produce headers for, and defaults to the +current architecture. The linux/asm directory of the exported kernel headers +is platform-specific, to see a complete list of supported architectures use +the command:: + + ls -d include/asm-* | sed 's/.*-//' + +INSTALL_HDR_PATH indicates where to install the headers. It defaults to +"./usr". + +An 'include' directory is automatically created inside INSTALL_HDR_PATH and +headers are installed in 'INSTALL_HDR_PATH/include'. + +The kernel header export infrastructure is maintained by David Woodhouse +. -- cgit v1.3.1