#
b0687c11 |
| 04-Apr-2023 |
Noah Goldstein <goldstein.w.n@gmail.com> |
lib/rbtree: use '+' instead of '|' for setting color.
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 f
lib/rbtree: use '+' instead of '|' for setting color.
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 <goldstein.w.n@gmail.com> Cc: Michel Lespinasse <michel@lespinasse.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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#
d89775fc |
| 12-Aug-2020 |
Alexander A. Klimov <grandmaster@al2klimov.de> |
lib/: replace HTTP links with HTTPS ones
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. Klimo
lib/: replace HTTP links with HTTPS ones
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 <grandmaster@al2klimov.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Coly Li <colyli@suse.de> [crc64.c] Link: http://lkml.kernel.org/r/20200726112154.16510-1-grandmaster@al2klimov.de Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
8d994cad |
| 07-Apr-2020 |
chenqiwu <chenqiwu@xiaomi.com> |
lib/rbtree: fix coding style of assignments
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 <chenqiwu@x
lib/rbtree: fix coding style of assignments
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 <chenqiwu@xiaomi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Michel Lespinasse <walken@google.com> Link: http://lkml.kernel.org/r/1582621140-25850-1-git-send-email-qiwuchen55@gmail.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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9f973cb3 |
| 16-Jul-2019 |
Michel Lespinasse <walken@google.com> |
lib/rbtree: avoid generating code twice for the cached versions
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
lib/rbtree: avoid generating code twice for the cached versions
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 <walken@google.com> Acked-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
1a59d1b8 |
| 27-May-2019 |
Thomas Gleixner <tglx@linutronix.de> |
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156
Based on 1 normalized pattern(s):
this program is free software you can redistribute it and or modify it under the terms of th
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156
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 <tglx@linutronix.de> Reviewed-by: Allison Randal <allison@lohutok.net> Reviewed-by: Richard Fontana <rfontana@redhat.com> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190527070033.113240726@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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#
338f1d9d |
| 14-Dec-2017 |
Chris Wilson <chris@chris-wilson.co.uk> |
lib/rbtree,drm/mm: add rbtree_replace_node_cached()
Add a variant of rbtree_replace_node() that maintains the leftmost cache of struct rbtree_root_cached when replacing nodes within the rbtree.
As
lib/rbtree,drm/mm: add rbtree_replace_node_cached()
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 <chris@chris-wilson.co.uk> Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Acked-by: Davidlohr Bueso <dbueso@suse.de> Cc: Jérôme Glisse <jglisse@redhat.com> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
35dc67d7 |
| 08-Sep-2017 |
Davidlohr Bueso <dave@stgolabs.net> |
rbtree: add some additional comments for rebalancing cases
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
rbtree: add some additional comments for rebalancing cases
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 <dbueso@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
2aadf7fc |
| 08-Sep-2017 |
Davidlohr Bueso <dave@stgolabs.net> |
rbtree: optimize root-check during rebalancing loop
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
rbtree: optimize root-check during rebalancing loop
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 <dbueso@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
cd9e61ed |
| 08-Sep-2017 |
Davidlohr Bueso <dave@stgolabs.net> |
rbtree: cache leftmost node internally
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 over
rbtree: cache leftmost node internally
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 <dbueso@suse.de> Reviewed-by: Jan Kara <jack@suse.cz> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
f231aebf |
| 24-Feb-2017 |
Kees Cook <keescook@chromium.org> |
rbtree: use designated initializers
Prepare to mark sensitive kernel structures for randomization by making sure they're using designated initializers. These were identified during allyesconfig bui
rbtree: use designated initializers
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 <keescook@chromium.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: David Howells <dhowells@redhat.com> Cc: Jie Chen <fykcee1@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
ce093a04 |
| 13-Dec-2016 |
Jie Chen <fykcee1@gmail.com> |
lib/rbtree.c: fix typo in comment of ____rb_erase_color
In Case 3 of `sibling == parent->rb_right':
Right rotation will not change color of sl and S in the diagram (i.e. should not change "sl" to "
lib/rbtree.c: fix typo in comment of ____rb_erase_color
In Case 3 of `sibling == parent->rb_right':
Right rotation will not change color of sl and S in the diagram (i.e. should not change "sl" to "Sl", "S" to "s")
In Case 3 of `sibling == parent->rb_left':
(p) (p) / \ / \ S N --> sr N / \ / Sl sr S / Sl
This is actually left rotation at "S", not right rotation.
In Case 4 of `sibling == parent->rb_left':
(p) (s) / \ / \ S N --> Sl P / \ / \ sl (sr) (sr) N
This is actually right rotation at "(p)" + color flips, not left rotation + color flips.
Link: http://lkml.kernel.org/r/1472391115-3702-1-git-send-email-fykcee1@gmail.com Signed-off-by: Jie Chen <fykcee1@gmail.com> Cc: Wei Yang <weiyang@linux.vnet.ibm.com> Cc: Xiao Guangrong <guangrong.xiao@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
c1adf200 |
| 01-Jul-2016 |
David Howells <dhowells@redhat.com> |
Introduce rb_replace_node_rcu()
Implement an RCU-safe variant of rb_replace_node() and rearrange rb_replace_node() to do things in the same order.
Signed-off-by: David Howells <dhowells@redhat.com>
Introduce rb_replace_node_rcu()
Implement an RCU-safe variant of rb_replace_node() and rearrange rb_replace_node() to do things in the same order.
Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
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d72da4a4 |
| 27-May-2015 |
Peter Zijlstra <peterz@infradead.org> |
rbtree: Make lockless searches non-fatal
Change the insert and erase code such that lockless searches are non-fatal.
In and of itself an rbtree cannot be correctly searched while in-modification, w
rbtree: Make lockless searches non-fatal
Change the insert and erase code such that lockless searches are non-fatal.
In and of itself an rbtree cannot be correctly searched while in-modification, we can however provide weaker guarantees that will allow the rbtree to be used in conjunction with other techniques, such as latches; see 9b0fd802e8c0 ("seqcount: Add raw_write_seqcount_latch()").
For this to work we need the following guarantees from the rbtree code:
1) a lockless reader must not see partial stores, this would allow it to observe nodes that are invalid memory.
2) there must not be (temporary) loops in the tree structure in the modifier's program order, this would cause a lookup which interrupts the modifier to get stuck indefinitely.
For 1) we must use WRITE_ONCE() for all updates to the tree structure; in particular this patch only does rb_{left,right} as those are the only element required for simple searches.
It generates slightly worse code, probably because volatile. But in pointer chasing heavy code a few instructions more should not matter.
For 2) I have carefully audited the code and drawn every intermediate link state and not found a loop.
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Woodhouse <David.Woodhouse@intel.com> Cc: Rik van Riel <riel@redhat.com> Reviewed-by: Michel Lespinasse <walken@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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#
1b9c53e8 |
| 08-Aug-2014 |
Wei Yang <weiyang@linux.vnet.ibm.com> |
lib/rbtree.c: fix typo in comment of __rb_insert()
In case 1, it passes down the BLACK color from G to p and u, and maintains the color of n. By doing so, it maintains the black height of the sub-t
lib/rbtree.c: fix typo in comment of __rb_insert()
In case 1, it passes down the BLACK color from G to p and u, and maintains the color of n. By doing so, it maintains the black height of the sub-tree.
While in the comment, it marks the color of n to BLACK. This is a typo and not consistents with the code.
This patch fixs this typo in comment.
Signed-off-by: Wei Yang <weiyang@linux.vnet.ibm.com> Acked-by: Michel Lespinasse <walken@google.com> Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
9dee5c51 |
| 11-Sep-2013 |
Cody P Schafer <cody@linux.vnet.ibm.com> |
rbtree: add postorder iteration functions
Postorder iteration yields all of a node's children prior to yielding the node itself, and this particular implementation also avoids examining the leaf lin
rbtree: add postorder iteration functions
Postorder iteration yields all of a node's children prior to yielding the node itself, and this particular implementation also avoids examining the leaf links in a node after that node has been yielded.
In what I expect will be its most common usage, postorder iteration allows the deletion of every node in an rbtree without modifying the rbtree nodes (no _requirement_ that they be nulled) while avoiding referencing child nodes after they have been "deleted" (most commonly, freed).
I have only updated zswap to use this functionality at this point, but numerous bits of code (most notably in the filesystem drivers) use a hand rolled postorder iteration that NULLs child links as it traverses the tree. Each of those instances could be replaced with this common implementation.
1 & 2 add rbtree postorder iteration functions. 3 adds testing of the iteration to the rbtree runtime tests 4 allows building the rbtree runtime tests as builtins 5 updates zswap.
This patch:
Add postorder iteration functions for rbtree. These are useful for safely freeing an entire rbtree without modifying the tree at all.
Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com> Reviewed-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Cc: David Woodhouse <David.Woodhouse@intel.com> Cc: Rik van Riel <riel@redhat.com> Cc: Michel Lespinasse <walken@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
3cb7a563 |
| 11-Jan-2013 |
Michel Lespinasse <walken@google.com> |
lib/rbtree.c: avoid the use of non-static __always_inline
lib/rbtree.c declared __rb_erase_color() as __always_inline void, and then exported it with EXPORT_SYMBOL.
This was because __rb_erase_colo
lib/rbtree.c: avoid the use of non-static __always_inline
lib/rbtree.c declared __rb_erase_color() as __always_inline void, and then exported it with EXPORT_SYMBOL.
This was because __rb_erase_color() must be exported for augmented rbtree users, but it must also be inlined into rb_erase() so that the dummy callback can get optimized out of that call site.
(Actually with a modern compiler, none of the dummy callback functions should even be generated as separate text functions).
The above usage is legal C, but it was unusual enough for some compilers to warn about it. This change makes things more explicit, with a static __always_inline ____rb_erase_color function for use in rb_erase(), and a separate non-inline __rb_erase_color function for use in rb_erase_augmented call sites.
Signed-off-by: Michel Lespinasse <walken@google.com> Reported-by: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
9c079add |
| 08-Oct-2012 |
Michel Lespinasse <walken@google.com> |
rbtree: move augmented rbtree functionality to rbtree_augmented.h
Provide rb_insert_augmented() and rb_erase_augmented() through a new rbtree_augmented.h include file. rb_erase_augmented() is defin
rbtree: move augmented rbtree functionality to rbtree_augmented.h
Provide rb_insert_augmented() and rb_erase_augmented() through a new rbtree_augmented.h include file. rb_erase_augmented() is defined there as an __always_inline function, in order to allow inlining of augmented rbtree callbacks into it. Since this generates a relatively large function, each augmented rbtree user should make sure to have a single call site.
Signed-off-by: Michel Lespinasse <walken@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Woodhouse <dwmw2@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
9d9e6f97 |
| 08-Oct-2012 |
Michel Lespinasse <walken@google.com> |
rbtree: remove prior augmented rbtree implementation
convert arch/x86/mm/pat_rbtree.c to the proposed augmented rbtree api and remove the old augmented rbtree implementation.
Signed-off-by: Michel
rbtree: remove prior augmented rbtree implementation
convert arch/x86/mm/pat_rbtree.c to the proposed augmented rbtree api and remove the old augmented rbtree implementation.
Signed-off-by: Michel Lespinasse <walken@google.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Woodhouse <dwmw2@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
14b94af0 |
| 08-Oct-2012 |
Michel Lespinasse <walken@google.com> |
rbtree: faster augmented rbtree manipulation
Introduce new augmented rbtree APIs that allow minimal recalculation of augmented node information.
A new callback is added to the rbtree insertion and
rbtree: faster augmented rbtree manipulation
Introduce new augmented rbtree APIs that allow minimal recalculation of augmented node information.
A new callback is added to the rbtree insertion and erase rebalancing functions, to be called on each tree rotations. Such rotations preserve the subtree's root augmented value, but require recalculation of the one child that was previously located at the subtree root.
In the insertion case, the handcoded search phase must be updated to maintain the augmented information on insertion, and then the rbtree coloring/rebalancing algorithms keep it up to date.
In the erase case, things are more complicated since it is library code that manipulates the rbtree in order to remove internal nodes. This requires a couple additional callbacks to copy a subtree's augmented value when a new root is stitched in, and to recompute augmented values down the ancestry path when a node is removed from the tree.
In order to preserve maximum speed for the non-augmented case, we provide two versions of each tree manipulation function. rb_insert_augmented() is the augmented equivalent of rb_insert_color(), and rb_erase_augmented() is the augmented equivalent of rb_erase().
Signed-off-by: Michel Lespinasse <walken@google.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Woodhouse <dwmw2@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
4f035ad6 |
| 08-Oct-2012 |
Michel Lespinasse <walken@google.com> |
rbtree: low level optimizations in rb_erase()
Various minor optimizations in rb_erase(): - Avoid multiple loading of node->__rb_parent_color when computing parent and color information (possibly n
rbtree: low level optimizations in rb_erase()
Various minor optimizations in rb_erase(): - Avoid multiple loading of node->__rb_parent_color when computing parent and color information (possibly not in close sequence, as there might be further branches in the algorithm) - In the 1-child subcase of case 1, copy the __rb_parent_color field from the erased node to the child instead of recomputing it from the desired parent and color - When searching for the erased node's successor, differentiate between cases 2 and 3 based on whether any left links were followed. This avoids a condition later down. - In case 3, keep a pointer to the erased node's right child so we don't have to refetch it later to adjust its parent. - In the no-childs subcase of cases 2 and 3, place the rebalance assigment last so that the compiler can remove the following if(rebalance) test.
Also, added some comments to illustrate cases 2 and 3.
Signed-off-by: Michel Lespinasse <walken@google.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Woodhouse <dwmw2@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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46b6135a |
| 08-Oct-2012 |
Michel Lespinasse <walken@google.com> |
rbtree: handle 1-child recoloring in rb_erase() instead of rb_erase_color()
An interesting observation for rb_erase() is that when a node has exactly one child, the node must be black and the child
rbtree: handle 1-child recoloring in rb_erase() instead of rb_erase_color()
An interesting observation for rb_erase() is that when a node has exactly one child, the node must be black and the child must be red. An interesting consequence is that removing such a node can be done by simply replacing it with its child and making the child black, which we can do efficiently in rb_erase(). __rb_erase_color() then only needs to handle the no-childs case and can be modified accordingly.
Signed-off-by: Michel Lespinasse <walken@google.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Woodhouse <dwmw2@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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60670b80 |
| 08-Oct-2012 |
Michel Lespinasse <walken@google.com> |
rbtree: place easiest case first in rb_erase()
In rb_erase, move the easy case (node to erase has no more than 1 child) first. I feel the code reads easier that way.
Signed-off-by: Michel Lespinass
rbtree: place easiest case first in rb_erase()
In rb_erase, move the easy case (node to erase has no more than 1 child) first. I feel the code reads easier that way.
Signed-off-by: Michel Lespinasse <walken@google.com> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Woodhouse <dwmw2@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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7abc704a |
| 08-Oct-2012 |
Michel Lespinasse <walken@google.com> |
rbtree: add __rb_change_child() helper function
Add __rb_change_child() as an inline helper function to replace code that would otherwise be duplicated 4 times in the source.
No changes to binary s
rbtree: add __rb_change_child() helper function
Add __rb_change_child() as an inline helper function to replace code that would otherwise be duplicated 4 times in the source.
No changes to binary size or speed.
Signed-off-by: Michel Lespinasse <walken@google.com> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Woodhouse <dwmw2@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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59633abf |
| 08-Oct-2012 |
Michel Lespinasse <walken@google.com> |
rbtree: optimize fetching of sibling node
When looking to fetch a node's sibling, we went through a sequence of: - check if node is the parent's left child - if it is, then fetch the parent's right
rbtree: optimize fetching of sibling node
When looking to fetch a node's sibling, we went through a sequence of: - check if node is the parent's left child - if it is, then fetch the parent's right child
This can be replaced with: - fetch the parent's right child as an assumed sibling - check that node is NOT the fetched child
This avoids fetching the parent's left child when node is actually that child. Saves a bit on code size, though it doesn't seem to make a large difference in speed.
Signed-off-by: Michel Lespinasse <walken@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Woodhouse <David.Woodhouse@intel.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Daniel Santos <daniel.santos@pobox.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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7ce6ff9e |
| 08-Oct-2012 |
Michel Lespinasse <walken@google.com> |
rbtree: coding style adjustments
Set comment and indentation style to be consistent with linux coding style and the rest of the file, as suggested by Peter Zijlstra
Signed-off-by: Michel Lespinasse
rbtree: coding style adjustments
Set comment and indentation style to be consistent with linux coding style and the rest of the file, as suggested by Peter Zijlstra
Signed-off-by: Michel Lespinasse <walken@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Acked-by: David Woodhouse <David.Woodhouse@intel.com> Cc: Rik van Riel <riel@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Daniel Santos <daniel.santos@pobox.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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