kernel/linux.git/lib/rbtree.c, branch v6.6.132

lib/rbtree: use '+' instead of '|' for setting color.

2023-04-18T23:39:33+00:00

This has a slight benefit for x86 and has no effect on other targets. The benefit to x86 is it change the codegen for setting a node to block from `mov %r0, %r1; or $RB_BLACK, %r1` to `lea RB_BLACK(%r0), %r1` which saves an instructions. In all other cases it just replace ALU with ALU (or -> and) which perform the same on all machines I am aware of. Total instructions in rbtree.o: Before - 802 After - 782 so it saves about 20 `mov` instructions. Link: https://lkml.kernel.org/r/20230404221350.3806566-1-goldstein.w.n@gmail.com Signed-off-by: Noah Goldstein Cc: Michel Lespinasse Signed-off-by: Andrew Morton

lib/: replace HTTP links with HTTPS ones

2020-08-12T17:58:00+00:00

Rationale: Reduces attack surface on kernel devs opening the links for MITM as HTTPS traffic is much harder to manipulate. Signed-off-by: Alexander A. Klimov Signed-off-by: Andrew Morton Acked-by: Coly Li [crc64.c] Link: http://lkml.kernel.org/r/20200726112154.16510-1-grandmaster@al2klimov.de Signed-off-by: Linus Torvalds

lib/rbtree: fix coding style of assignments

2020-04-07T17:43:43+00:00

Leave blank space between the right-hand and left-hand side of the assignment to meet the kernel coding style better. Signed-off-by: chenqiwu Signed-off-by: Andrew Morton Reviewed-by: Michel Lespinasse Link: http://lkml.kernel.org/r/1582621140-25850-1-git-send-email-qiwuchen55@gmail.com Signed-off-by: Linus Torvalds

lib/rbtree: avoid generating code twice for the cached versions

2019-07-17T02:23:22+00:00

As was already noted in rbtree.h, the logic to cache rb_first (or rb_last) can easily be implemented externally to the core rbtree api. Change the implementation to do just that. Previously the update of rb_leftmost was wired deeper into the implmentation, but there were some disadvantages to that - mostly, lib/rbtree.c had separate instantiations for rb_insert_color() vs rb_insert_color_cached(), as well as rb_erase() vs rb_erase_cached(), which were doing exactly the same thing save for the rb_leftmost update at the start of either function. text data bss dec hex filename 5405 120 0 5525 1595 lib/rbtree.o-vanilla 3827 96 0 3923 f53 lib/rbtree.o-patch [dave@stgolabs.net: changelog addition] Link: http://lkml.kernel.org/r/20190628171416.by5gdizl3rcxk5h5@linux-r8p5 [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/20190628045008.39926-1-walken@google.com Signed-off-by: Michel Lespinasse Acked-by: Davidlohr Bueso Acked-by: Peter Zijlstra (Intel) Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156

2019-05-30T18:26:35+00:00

Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license as published by the free software foundation either version 2 of the license or at your option any later version this program is distributed in the hope that it will be useful but without any warranty without even the implied warranty of merchantability or fitness for a particular purpose see the gnu general public license for more details you should have received a copy of the gnu general public license along with this program if not write to the free software foundation inc 59 temple place suite 330 boston ma 02111 1307 usa extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 1334 file(s). Signed-off-by: Thomas Gleixner Reviewed-by: Allison Randal Reviewed-by: Richard Fontana Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190527070033.113240726@linutronix.de Signed-off-by: Greg Kroah-Hartman

lib/rbtree,drm/mm: add rbtree_replace_node_cached()

2017-12-15T00:00:48+00:00

Add a variant of rbtree_replace_node() that maintains the leftmost cache of struct rbtree_root_cached when replacing nodes within the rbtree. As drm_mm is the only rb_replace_node() being used on an interval tree, the mistake looks fairly self-contained. Furthermore the only user of drm_mm_replace_node() is its testsuite... Testcase: igt/drm_mm/replace Link: http://lkml.kernel.org/r/20171122100729.3742-1-chris@chris-wilson.co.uk Link: https://patchwork.freedesktop.org/patch/msgid/20171109212435.9265-1-chris@chris-wilson.co.uk Fixes: f808c13fd373 ("lib/interval_tree: fast overlap detection") Signed-off-by: Chris Wilson Reviewed-by: Joonas Lahtinen Acked-by: Davidlohr Bueso Cc: Jérôme Glisse Cc: Joonas Lahtinen Cc: Daniel Vetter Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

rbtree: add some additional comments for rebalancing cases

2017-09-09T01:26:48+00:00

While overall the code is very nicely commented, it might not be immediately obvious from the diagrams what is going on. Add a very brief summary of each case. Opposite cases where the node is the left child are left untouched. Link: http://lkml.kernel.org/r/20170719014603.19029-4-dave@stgolabs.net Signed-off-by: Davidlohr Bueso Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

rbtree: optimize root-check during rebalancing loop

2017-09-09T01:26:48+00:00

The only times the nil-parent (root node) condition is true is when the node is the first in the tree, or after fixing rbtree rule #4 and the case 1 rebalancing made the node the root. Such conditions do not apply most of the time: (i) The common case in an rbtree is to have more than a single node, so this is only true for the first rb_insert(). (ii) While there is a chance only one first rotation is needed, cases where the node's uncle is black (cases 2,3) are more common as we can have the following scenarios during the rotation looping: case1 only, case1+1, case2+3, case1+2+3, case3 only, etc. This patch, therefore, adds an unlikely() optimization to this conditional. When profiling with CONFIG_PROFILE_ANNOTATED_BRANCHES, a kernel build shows that the incorrect rate is less than 15%, and for workloads that involve insert mostly trees overtime tend to have less than 2% incorrect rate. Link: http://lkml.kernel.org/r/20170719014603.19029-3-dave@stgolabs.net Signed-off-by: Davidlohr Bueso Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

rbtree: cache leftmost node internally

2017-09-09T01:26:48+00:00

Patch series "rbtree: Cache leftmost node internally", v4. A series to extending rbtrees to internally cache the leftmost node such that we can have fast overlap check optimization for all interval tree users[1]. The benefits of this series are that: (i) Unify users that do internal leftmost node caching. (ii) Optimize all interval tree users. (iii) Convert at least two new users (epoll and procfs) to the new interface. This patch (of 16): Red-black tree semantics imply that nodes with smaller or greater (or equal for duplicates) keys always be to the left and right, respectively. For the kernel this is extremely evident when considering our rb_first() semantics. Enabling lookups for the smallest node in the tree in O(1) can save a good chunk of cycles in not having to walk down the tree each time. To this end there are a few core users that explicitly do this, such as the scheduler and rtmutexes. There is also the desire for interval trees to have this optimization allowing faster overlap checking. This patch introduces a new 'struct rb_root_cached' which is just the root with a cached pointer to the leftmost node. The reason why the regular rb_root was not extended instead of adding a new structure was that this allows the user to have the choice between memory footprint and actual tree performance. The new wrappers on top of the regular rb_root calls are: - rb_first_cached(cached_root) -- which is a fast replacement for rb_first. - rb_insert_color_cached(node, cached_root, new) - rb_erase_cached(node, cached_root) In addition, augmented cached interfaces are also added for basic insertion and deletion operations; which becomes important for the interval tree changes. With the exception of the inserts, which adds a bool for updating the new leftmost, the interfaces are kept the same. To this end, porting rb users to the cached version becomes really trivial, and keeping current rbtree semantics for users that don't care about the optimization requires zero overhead. Link: http://lkml.kernel.org/r/20170719014603.19029-2-dave@stgolabs.net Signed-off-by: Davidlohr Bueso Reviewed-by: Jan Kara Acked-by: Peter Zijlstra (Intel) Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

rbtree: use designated initializers

2017-02-25T01:46:57+00:00

Prepare to mark sensitive kernel structures for randomization by making sure they're using designated initializers. These were identified during allyesconfig builds of x86, arm, and arm64, with most initializer fixes extracted from grsecurity. Link: http://lkml.kernel.org/r/20161217010253.GA140470@beast Signed-off-by: Kees Cook Acked-by: Peter Zijlstra (Intel) Cc: David Howells Cc: Jie Chen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds