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2009-06-17rb_tree: remove redundant if()-condition in rb_erase()Wolfram Strepp
Furthermore, notice that the initial checks: if (!node->rb_left) child = node->rb_right; else if (!node->rb_right) child = node->rb_left; else { ... } guarantee that old->rb_right is set in the final else branch, therefore we can omit checking that again. Signed-off-by: Wolfram Strepp <wstrepp@gmx.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-06-17rb_tree: make clear distinction between two different cases in rb_erase()Wolfram Strepp
There are two cases when a node, having 2 childs, is erased: 'normal case': the successor is not the right-hand-child of the node to be erased 'special case': the successor is the right-hand child of the node to be erased Here some ascii-art, with following symbols (referring to the code): O: node to be deleted N: the successor of O P: parent of N C: child of N L: some other node normal case: O N / \ / \ / \ / \ L \ L \ / \ P ----> / \ P / \ / \ / / N C \ / \ \ C / \ special case: O|P N / \ / \ / \ / \ L \ L \ / \ N ----> / C \ / \ \ C / \ Notice that for the special case we don't have to reconnect C to N. Signed-off-by: Wolfram Strepp <wstrepp@gmx.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-06-17rb_tree: reorganize code in rb_erase() for additional changesWolfram Strepp
First, move some code around in order to make the next change more obvious. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Wolfram Strepp <wstrepp@gmx.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-01lib/rbtree.c: optimize rb_erase()Wolfram Strepp
Tfour 4 redundant if-conditions in function __rb_erase_color() in lib/rbtree.c are removed. In pseudo-source-code, the structure of the code is as follows: if ((!A || B) && (!C || D)) { . . . } else { if (!C || D) {//if this is true, it implies: (A == true) && (B == false) if (A) {//hence this always evaluates to 'true'... . } . //at this point, C always becomes true, because of: __rb_rotate_right/left(); //and: other = parent->rb_right/left; } . . if (C) {//...and this too ! . } } Signed-off-by: Wolfram Strepp <wstrepp@gmx.de> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Andrea Arcangeli <andrea@qumranet.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-10rbtree: add const qualifier to some functionsArtem Bityutskiy
The 'rb_first()', 'rb_last()', 'rb_next()' and 'rb_prev()' calls take a pointer to an RB node or RB root. They do not change the pointed objects, so add a 'const' qualifier in order to make life of the users of these functions easier. Indeed, if I have my own constant pointer &const struct my_type *p, and I call 'rb_next(&p->rb)', I get a GCC warning: warning: passing argument 1 of ‘rb_next’ discards qualifiers from pointer target type Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com> Signed-off-by: David Woodhouse <David.Woodhouse@intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2006-09-30[PATCH] rbtree: fixed reversed RB_EMPTY_NODE and rb_next/prevJens Axboe
The conditions got reserved. Also make rb_next() and rb_prev() check for the empty condition. Signed-off-by: Jens Axboe <axboe@suse.de>
2006-06-05[RBTREE] Switch rb_colour() et al to en_US spelling of 'color' for consistencyDavid Woodhouse
Since rb_insert_color() is part of the _public_ API, while the others are purely internal, switch to be consistent with that. Signed-off-by: David Woodhouse <dwmw2@infradead.org>
2006-04-21[RBTREE] Merge colour and parent fields of struct rb_node.David Woodhouse
We only used a single bit for colour information, so having a whole machine word of space allocated for it was a bit wasteful. Instead, store it in the lowest bit of the 'parent' pointer, since that was always going to be aligned anyway. Signed-off-by: David Woodhouse <dwmw2@infradead.org>
2006-04-21[RBTREE] Remove dead code in rb_erase()David Woodhouse
Observe rb_erase(), when the victim node 'old' has two children so neither of the simple cases at the beginning are taken. Observe that it effectively does an 'rb_next()' operation to find the next (by value) node in the tree. That is; we go to the victim's right-hand child and then follow left-hand pointers all the way down the tree as far as we can until we find the next node 'node'. We end up with 'node' being either the same immediate right-hand child of 'old', or one of its descendants on the far left-hand side. For a start, we _know_ that 'node' has a parent. We can drop that check. We also know that if 'node's parent is 'old', then 'node' is the right-hand child of its parent. And that if 'node's parent is _not_ 'old', then 'node' is the left-hand child of its parent. So instead of checking for 'node->rb_parent == old' in one place and also checking 'node's heritage separately when we're trying to change its link from its parent, we can shuffle things around a bit and do it like this... Signed-off-by: David Woodhouse <dwmw2@infradead.org>
2005-04-16Linux-2.6.12-rc2Linus Torvalds
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!