1 /* SPDX-License-Identifier: (GPL-2.0 or LGPL-2.1)
5 * wrapper around global_dirty_limit read. Using KALLSYMS with KALLSYMS_ALL
6 * to get its address when available, else we need to have a kernel that
7 * exports this variable to GPL modules.
9 * Copyright (C) 2013 Mentor Graphics Corp.
12 #ifndef _LTTNG_WRAPPER_WRITEBACK_H
13 #define _LTTNG_WRAPPER_WRITEBACK_H
15 #include <lttng-kernel-version.h>
17 #ifdef CONFIG_KALLSYMS_ALL
18 #include <linux/kallsyms.h>
19 #include <wrapper/kallsyms.h>
23 #if LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,2,0)
25 static struct wb_domain
*global_wb_domain_sym
;
28 unsigned long wrapper_global_dirty_limit(void)
30 if (!global_wb_domain_sym
)
31 global_wb_domain_sym
=
32 (void *) kallsyms_lookup_dataptr("global_wb_domain");
33 if (global_wb_domain_sym
) {
34 return global_wb_domain_sym
->dirty_limit
;
36 printk_once(KERN_WARNING
"LTTng: global_wb_domain symbol lookup failed.\n");
42 * Canary function to check for 'global_wb_domain' at compile time.
44 * From 'include/linux/writeback.h':
46 * extern struct wb_domain global_wb_domain;
49 unsigned long __canary__global_wb_domain(void)
51 return global_wb_domain
.dirty_limit
;
54 #elif LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(3,1,0)
56 static unsigned long *global_dirty_limit_sym
;
59 unsigned long wrapper_global_dirty_limit(void)
61 if (!global_dirty_limit_sym
)
62 global_dirty_limit_sym
=
63 (void *) kallsyms_lookup_dataptr("global_dirty_limit");
64 if (global_dirty_limit_sym
) {
65 return *global_dirty_limit_sym
;
67 printk_once(KERN_WARNING
"LTTng: global_dirty_limit symbol lookup failed.\n");
73 * Canary function to check for 'global_dirty_limit' at compile time.
75 * From 'include/linux/writeback.h':
77 * extern unsigned long global_dirty_limit;
80 unsigned long __canary__global_dirty_limit(void)
82 return global_dirty_limit
;
87 #else /* CONFIG_KALLSYMS_ALL */
89 #include <linux/writeback.h>
91 #if LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(3,1,0)
93 unsigned long wrapper_global_dirty_limit(void)
95 return global_dirty_limit
;
101 #endif /* _LTTNG_WRAPPER_WRITEBACK_H */
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