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/* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
*
* wrapper/writeback.h
*
* wrapper around global_dirty_limit read. Using KALLSYMS with KALLSYMS_ALL
* to get its address when available, else we need to have a kernel that
* exports this variable to GPL modules.
*
* Copyright (C) 2013 Mentor Graphics Corp.
*/
#ifndef _LTTNG_WRAPPER_WRITEBACK_H
#define _LTTNG_WRAPPER_WRITEBACK_H
#ifdef CONFIG_KALLSYMS_ALL
#include <linux/kallsyms.h>
#include <wrapper/kallsyms.h>
static struct wb_domain *global_wb_domain_sym;
static inline
unsigned long wrapper_global_dirty_limit(void)
{
if (!global_wb_domain_sym)
global_wb_domain_sym =
(void *) kallsyms_lookup_dataptr("global_wb_domain");
if (global_wb_domain_sym) {
return global_wb_domain_sym->dirty_limit;
} else {
printk_once(KERN_WARNING "LTTng: global_wb_domain symbol lookup failed.\n");
return 0;
}
}
/*
* Canary function to check for 'global_wb_domain' at compile time.
*
* From 'include/linux/writeback.h':
*
* extern struct wb_domain global_wb_domain;
*/
static inline
unsigned long __canary__global_wb_domain(void)
{
return global_wb_domain.dirty_limit;
}
#else /* CONFIG_KALLSYMS_ALL */
#include <linux/writeback.h>
static inline
unsigned long wrapper_global_dirty_limit(void)
{
return global_dirty_limit;
}
#endif /* CONFIG_KALLSYMS_ALL */
#endif /* _LTTNG_WRAPPER_WRITEBACK_H */
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