cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
Log | Files | Refs | README | LICENSE | sfeed.txt

string_table.c (2257B)

      1// SPDX-License-Identifier: GPL-2.0
      2#include <linux/slab.h>
      3#include <linux/gfp.h>
      4#include <linux/string.h>
      5#include <linux/spinlock.h>
      6#include <linux/ceph/string_table.h>
      7
      8static DEFINE_SPINLOCK(string_tree_lock);
      9static struct rb_root string_tree = RB_ROOT;
     10
     11struct ceph_string *ceph_find_or_create_string(const char* str, size_t len)
     12{
     13	struct ceph_string *cs, *exist;
     14	struct rb_node **p, *parent;
     15	int ret;
     16
     17	exist = NULL;
     18	spin_lock(&string_tree_lock);
     19	p = &string_tree.rb_node;
     20	while (*p) {
     21		exist = rb_entry(*p, struct ceph_string, node);
     22		ret = ceph_compare_string(exist, str, len);
     23		if (ret > 0)
     24			p = &(*p)->rb_left;
     25		else if (ret < 0)
     26			p = &(*p)->rb_right;
     27		else
     28			break;
     29		exist = NULL;
     30	}
     31	if (exist && !kref_get_unless_zero(&exist->kref)) {
     32		rb_erase(&exist->node, &string_tree);
     33		RB_CLEAR_NODE(&exist->node);
     34		exist = NULL;
     35	}
     36	spin_unlock(&string_tree_lock);
     37	if (exist)
     38		return exist;
     39
     40	cs = kmalloc(sizeof(*cs) + len + 1, GFP_NOFS);
     41	if (!cs)
     42		return NULL;
     43
     44	kref_init(&cs->kref);
     45	cs->len = len;
     46	memcpy(cs->str, str, len);
     47	cs->str[len] = 0;
     48
     49retry:
     50	exist = NULL;
     51	parent = NULL;
     52	p = &string_tree.rb_node;
     53	spin_lock(&string_tree_lock);
     54	while (*p) {
     55		parent = *p;
     56		exist = rb_entry(*p, struct ceph_string, node);
     57		ret = ceph_compare_string(exist, str, len);
     58		if (ret > 0)
     59			p = &(*p)->rb_left;
     60		else if (ret < 0)
     61			p = &(*p)->rb_right;
     62		else
     63			break;
     64		exist = NULL;
     65	}
     66	ret = 0;
     67	if (!exist) {
     68		rb_link_node(&cs->node, parent, p);
     69		rb_insert_color(&cs->node, &string_tree);
     70	} else if (!kref_get_unless_zero(&exist->kref)) {
     71		rb_erase(&exist->node, &string_tree);
     72		RB_CLEAR_NODE(&exist->node);
     73		ret = -EAGAIN;
     74	}
     75	spin_unlock(&string_tree_lock);
     76	if (ret == -EAGAIN)
     77		goto retry;
     78
     79	if (exist) {
     80		kfree(cs);
     81		cs = exist;
     82	}
     83
     84	return cs;
     85}
     86EXPORT_SYMBOL(ceph_find_or_create_string);
     87
     88void ceph_release_string(struct kref *ref)
     89{
     90	struct ceph_string *cs = container_of(ref, struct ceph_string, kref);
     91
     92	spin_lock(&string_tree_lock);
     93	if (!RB_EMPTY_NODE(&cs->node)) {
     94		rb_erase(&cs->node, &string_tree);
     95		RB_CLEAR_NODE(&cs->node);
     96	}
     97	spin_unlock(&string_tree_lock);
     98
     99	kfree_rcu(cs, rcu);
    100}
    101EXPORT_SYMBOL(ceph_release_string);
    102
    103bool ceph_strings_empty(void)
    104{
    105	return RB_EMPTY_ROOT(&string_tree);
    106}