Linux Kernel - Red/Black Trees
- by CodeRanger
I'm trying to implement a red/black tree in Linux per task_struct using code from linux/rbtree.h. I can get a red/black tree inserting properly in a standalone space in the kernel such as a module but when I try to get the same code to function with the rb_root declared in either task_struct or task_struct-files_struct, I get a SEGFAULT everytime I try an insert.
Here's some code:
In task_struct I create a rb_root struct for my tree (not a pointer).
In init_task.h, macro INIT_TASK(tsk), I set this equal to RB_ROOT.
To do an insert, I use this code: rb_insert(&(current-fd_tree), &rbnode); This is where the issue occurs.
My insert command is the standard insert that is documented in all RBTree documentation for the kernel:
int my_insert(struct rb_root *root, struct mytype *data)
{
struct rb_node **new = &(root->rb_node), *parent = NULL;
/* Figure out where to put new node */
while (*new) {
struct mytype *this = container_of(*new, struct mytype, node);
int result = strcmp(data->keystring, this->keystring);
parent = *new;
if (result < 0)
new = &((*new)->rb_left);
else if (result > 0)
new = &((*new)->rb_right);
else
return FALSE;
}
/* Add new node and rebalance tree. */
rb_link_node(&data->node, parent, new);
rb_insert_color(&data->node, root);
return TRUE;
}
Is there something I'm missing? Some reason this would work fine if I made a tree root outside of task_struct? If I make rb_root inside of a module this insert works fine. But once I put the actual tree root in the task_struct or even in the task_struct-files_struct, I get a SEGFAULT. Can a root node not be added in these structs? Any tips are greatly appreciated. I've tried nearly everything I can think of.
