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rb_tree: silence coverity

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Add comments to RB_INSERT_COLOR to silence coverity warnings about the
use of an uninitialized variable.  Since other static analyzers will
complain too, add a comment to explain why the complaints are unwarranted.

Reviewed by:	markj
MFC after:	3 weeks
Differential Revision:	https://reviews.freebsd.org/D35671
This commit is contained in:
Doug Moore 2022-06-30 12:27:33 -05:00
parent b9c3e544c4
commit 91b30f7ad2
1 changed files with 13 additions and 0 deletions
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13
sys/sys/tree.h
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@ -462,6 +462,17 @@ struct { \
attr void \
name##_RB_INSERT_COLOR(struct name *head, struct type *elm) \
{ \
/* \
* Initially, elm is a leaf. Either its parent was previously \
* a leaf, with two black null children, or an interior node \
* with a black non-null child and a red null child. The \
* balance criterion "the rank of any leaf is 1" precludes the \
* possibility of two red null children for the initial parent. \
* So the first loop iteration cannot lead to accessing an \
* uninitialized 'child', and a later iteration can only happen \
* when a value has been assigned to 'child' in the previous \
* one. \
*/ \
struct type *child, *parent; \
while ((parent = RB_PARENT(elm, field)) != NULL) { \
if (RB_LEFT(parent, field) == elm) { \
@ -477,6 +488,7 @@ name##_RB_INSERT_COLOR(struct name *head, struct type *elm) \
} \
if (!RB_RED_RIGHT(elm, field)) { \
RB_FLIP_LEFT(elm, field); \
/* coverity[uninit_use] */ \
RB_ROTATE_LEFT(head, elm, child, field);\
if (RB_RED_LEFT(child, field)) \
RB_FLIP_RIGHT(elm, field); \
@ -498,6 +510,7 @@ name##_RB_INSERT_COLOR(struct name *head, struct type *elm) \
} \
if (!RB_RED_LEFT(elm, field)) { \
RB_FLIP_RIGHT(elm, field); \
/* coverity[uninit_use] */ \
RB_ROTATE_RIGHT(head, elm, child, field);\
if (RB_RED_RIGHT(child, field)) \
RB_FLIP_LEFT(elm, field); \