sysctl: pass kernel pointers to ->proc_handler

Instead of having all the sysctl handlers deal with user pointers, which
is rather hairy in terms of the BPF interaction, copy the input to and
from  userspace in common code.  This also means that the strings are
always NUL-terminated by the common code, making the API a little bit
safer.

As most handler just pass through the data to one of the common handlers
a lot of the changes are mechnical.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

18 files changed, 101 insertions, 143 deletions

diff --git a/include/linux/bpf-cgroup.h b/include/linux/bpf-cgroup.h
index c11b413d5b1a..0b41fd5fc96b 100644
--- a/include/linux/bpf-cgroup.h
+++ b/include/linux/bpf-cgroup.h
@@ -138,8 +138,7 @@ int __cgroup_bpf_check_dev_permission(short dev_type, u32 major, u32 minor,
 
 int __cgroup_bpf_run_filter_sysctl(struct ctl_table_header *head,
 				   struct ctl_table *table, int write,
-				   void __user *buf, size_t *pcount,
-				   loff_t *ppos, void **new_buf,
+				   void **buf, size_t *pcount, loff_t *ppos,
 				   enum bpf_attach_type type);
 
 int __cgroup_bpf_run_filter_setsockopt(struct sock *sock, int *level,
@@ -302,12 +301,12 @@ int bpf_percpu_cgroup_storage_update(struct bpf_map *map, void *key,
 })
 
 
-#define BPF_CGROUP_RUN_PROG_SYSCTL(head, table, write, buf, count, pos, nbuf)  \
+#define BPF_CGROUP_RUN_PROG_SYSCTL(head, table, write, buf, count, pos)  \
 ({									       \
 	int __ret = 0;							       \
 	if (cgroup_bpf_enabled)						       \
 		__ret = __cgroup_bpf_run_filter_sysctl(head, table, write,     \
-						       buf, count, pos, nbuf,  \
+						       buf, count, pos,        \
 						       BPF_CGROUP_SYSCTL);     \
 	__ret;								       \
 })
@@ -429,7 +428,7 @@ static inline int bpf_percpu_cgroup_storage_update(struct bpf_map *map,
 #define BPF_CGROUP_RUN_PROG_UDP6_RECVMSG_LOCK(sk, uaddr) ({ 0; })
 #define BPF_CGROUP_RUN_PROG_SOCK_OPS(sock_ops) ({ 0; })
 #define BPF_CGROUP_RUN_PROG_DEVICE_CGROUP(type,major,minor,access) ({ 0; })
-#define BPF_CGROUP_RUN_PROG_SYSCTL(head,table,write,buf,count,pos,nbuf) ({ 0; })
+#define BPF_CGROUP_RUN_PROG_SYSCTL(head,table,write,buf,count,pos) ({ 0; })
 #define BPF_CGROUP_GETSOCKOPT_MAX_OPTLEN(optlen) ({ 0; })
 #define BPF_CGROUP_RUN_PROG_GETSOCKOPT(sock, level, optname, optval, \
 				       optlen, max_optlen, retval) ({ retval; })
diff --git a/include/linux/compaction.h b/include/linux/compaction.h
index 4b898cdbdf05..a0eabfbeb0e1 100644
--- a/include/linux/compaction.h
+++ b/include/linux/compaction.h
@@ -86,7 +86,7 @@ static inline unsigned long compact_gap(unsigned int order)
 #ifdef CONFIG_COMPACTION
 extern int sysctl_compact_memory;
 extern int sysctl_compaction_handler(struct ctl_table *table, int write,
-			void __user *buffer, size_t *length, loff_t *ppos);
+			void *buffer, size_t *length, loff_t *ppos);
 extern int sysctl_extfrag_threshold;
 extern int sysctl_compact_unevictable_allowed;
 
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 4f6f59b4f22a..9b028d260649 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3536,11 +3536,11 @@ ssize_t simple_attr_write(struct file *file, const char __user *buf,
 
 struct ctl_table;
 int proc_nr_files(struct ctl_table *table, int write,
-		  void __user *buffer, size_t *lenp, loff_t *ppos);
+		  void *buffer, size_t *lenp, loff_t *ppos);
 int proc_nr_dentry(struct ctl_table *table, int write,
-		  void __user *buffer, size_t *lenp, loff_t *ppos);
+		  void *buffer, size_t *lenp, loff_t *ppos);
 int proc_nr_inodes(struct ctl_table *table, int write,
-		   void __user *buffer, size_t *lenp, loff_t *ppos);
+		   void *buffer, size_t *lenp, loff_t *ppos);
 int __init get_filesystem_list(char *buf);
 
 #define __FMODE_EXEC		((__force int) FMODE_EXEC)
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index db95244a62d4..ddfc377de0d2 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -1005,8 +1005,7 @@ extern void disable_trace_on_warning(void);
 extern int __disable_trace_on_warning;
 
 int tracepoint_printk_sysctl(struct ctl_table *table, int write,
-			     void __user *buffer, size_t *lenp,
-			     loff_t *ppos);
+			     void *buffer, size_t *lenp, loff_t *ppos);
 
 #else /* CONFIG_TRACING */
 static inline void  disable_trace_on_warning(void) { }
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 43a1cef8f0f1..92c21c5ccc58 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -105,14 +105,13 @@ struct hugepage_subpool *hugepage_new_subpool(struct hstate *h, long max_hpages,
 void hugepage_put_subpool(struct hugepage_subpool *spool);
 
 void reset_vma_resv_huge_pages(struct vm_area_struct *vma);
-int hugetlb_sysctl_handler(struct ctl_table *, int, void __user *, size_t *, loff_t *);
-int hugetlb_overcommit_handler(struct ctl_table *, int, void __user *, size_t *, loff_t *);
-int hugetlb_treat_movable_handler(struct ctl_table *, int, void __user *, size_t *, loff_t *);
-
-#ifdef CONFIG_NUMA
-int hugetlb_mempolicy_sysctl_handler(struct ctl_table *, int,
-					void __user *, size_t *, loff_t *);
-#endif
+int hugetlb_sysctl_handler(struct ctl_table *, int, void *, size_t *, loff_t *);
+int hugetlb_overcommit_handler(struct ctl_table *, int, void *, size_t *,
+		loff_t *);
+int hugetlb_treat_movable_handler(struct ctl_table *, int, void *, size_t *,
+		loff_t *);
+int hugetlb_mempolicy_sysctl_handler(struct ctl_table *, int, void *, size_t *,
+		loff_t *);
 
 int copy_hugetlb_page_range(struct mm_struct *, struct mm_struct *, struct vm_area_struct *);
 long follow_hugetlb_page(struct mm_struct *, struct vm_area_struct *,
diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
index 04bdaf01112c..594265bfd390 100644
--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h
@@ -312,7 +312,7 @@ DEFINE_INSN_CACHE_OPS(optinsn);
 #ifdef CONFIG_SYSCTL
 extern int sysctl_kprobes_optimization;
 extern int proc_kprobes_optimization_handler(struct ctl_table *table,
-					     int write, void __user *buffer,
+					     int write, void *buffer,
 					     size_t *length, loff_t *ppos);
 #endif
 extern void wait_for_kprobe_optimizer(void);
diff --git a/include/linux/latencytop.h b/include/linux/latencytop.h
index 9022f0c2e2e4..abe3d95f795b 100644
--- a/include/linux/latencytop.h
+++ b/include/linux/latencytop.h
@@ -38,8 +38,8 @@ account_scheduler_latency(struct task_struct *task, int usecs, int inter)
 
 void clear_tsk_latency_tracing(struct task_struct *p);
 
-extern int sysctl_latencytop(struct ctl_table *table, int write,
-			void __user *buffer, size_t *lenp, loff_t *ppos);
+int sysctl_latencytop(struct ctl_table *table, int write, void *buffer,
+		size_t *lenp, loff_t *ppos);
 
 #else
 
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 9c4e7e76dedd..a7b1ef8ed970 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -201,10 +201,10 @@ extern int sysctl_overcommit_memory;
 extern int sysctl_overcommit_ratio;
 extern unsigned long sysctl_overcommit_kbytes;
 
-extern int overcommit_ratio_handler(struct ctl_table *, int, void __user *,
-				    size_t *, loff_t *);
-extern int overcommit_kbytes_handler(struct ctl_table *, int, void __user *,
-				    size_t *, loff_t *);
+int overcommit_ratio_handler(struct ctl_table *, int, void *, size_t *,
+		loff_t *);
+int overcommit_kbytes_handler(struct ctl_table *, int, void *, size_t *,
+		loff_t *);
 
 #define nth_page(page,n) pfn_to_page(page_to_pfn((page)) + (n))
 
@@ -2957,8 +2957,8 @@ extern bool process_shares_mm(struct task_struct *p, struct mm_struct *mm);
 
 #ifdef CONFIG_SYSCTL
 extern int sysctl_drop_caches;
-int drop_caches_sysctl_handler(struct ctl_table *, int,
-					void __user *, size_t *, loff_t *);
+int drop_caches_sysctl_handler(struct ctl_table *, int, void *, size_t *,
+		loff_t *);
 #endif
 
 void drop_slab(void);
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index b2af594ef0f7..93cf20f41e26 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -910,22 +910,21 @@ static inline int is_highmem(struct zone *zone)
 /* These two functions are used to setup the per zone pages min values */
 struct ctl_table;
 
-int min_free_kbytes_sysctl_handler(struct ctl_table *, int,
-					void __user *, size_t *, loff_t *);
-int watermark_scale_factor_sysctl_handler(struct ctl_table *, int,
-					void __user *, size_t *, loff_t *);
+int min_free_kbytes_sysctl_handler(struct ctl_table *, int, void *, size_t *,
+		loff_t *);
+int watermark_scale_factor_sysctl_handler(struct ctl_table *, int, void *,
+		size_t *, loff_t *);
 extern int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES];
-int lowmem_reserve_ratio_sysctl_handler(struct ctl_table *, int,
-					void __user *, size_t *, loff_t *);
+int lowmem_reserve_ratio_sysctl_handler(struct ctl_table *, int, void *,
+		size_t *, loff_t *);
 int percpu_pagelist_fraction_sysctl_handler(struct ctl_table *, int,
-					void __user *, size_t *, loff_t *);
+		void *, size_t *, loff_t *);
 int sysctl_min_unmapped_ratio_sysctl_handler(struct ctl_table *, int,
-			void __user *, size_t *, loff_t *);
+		void *, size_t *, loff_t *);
 int sysctl_min_slab_ratio_sysctl_handler(struct ctl_table *, int,
-			void __user *, size_t *, loff_t *);
-
-extern int numa_zonelist_order_handler(struct ctl_table *, int,
-			void __user *, size_t *, loff_t *);
+		void *, size_t *, loff_t *);
+int numa_zonelist_order_handler(struct ctl_table *, int,
+		void *, size_t *, loff_t *);
 extern int percpu_pagelist_fraction;
 extern char numa_zonelist_order[];
 #define NUMA_ZONELIST_ORDER_LEN	16
diff --git a/include/linux/nmi.h b/include/linux/nmi.h
index 9003e29cde46..750c7f395ca9 100644
--- a/include/linux/nmi.h
+++ b/include/linux/nmi.h
@@ -202,16 +202,11 @@ static inline void watchdog_update_hrtimer_threshold(u64 period) { }
 #endif
 
 struct ctl_table;
-extern int proc_watchdog(struct ctl_table *, int ,
-			 void __user *, size_t *, loff_t *);
-extern int proc_nmi_watchdog(struct ctl_table *, int ,
-			     void __user *, size_t *, loff_t *);
-extern int proc_soft_watchdog(struct ctl_table *, int ,
-			      void __user *, size_t *, loff_t *);
-extern int proc_watchdog_thresh(struct ctl_table *, int ,
-				void __user *, size_t *, loff_t *);
-extern int proc_watchdog_cpumask(struct ctl_table *, int,
-				 void __user *, size_t *, loff_t *);
+int proc_watchdog(struct ctl_table *, int, void *, size_t *, loff_t *);
+int proc_nmi_watchdog(struct ctl_table *, int , void *, size_t *, loff_t *);
+int proc_soft_watchdog(struct ctl_table *, int , void *, size_t *, loff_t *);
+int proc_watchdog_thresh(struct ctl_table *, int , void *, size_t *, loff_t *);
+int proc_watchdog_cpumask(struct ctl_table *, int, void *, size_t *, loff_t *);
 
 #ifdef CONFIG_HAVE_ACPI_APEI_NMI
 #include <asm/nmi.h>
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 9c3e7619c929..347ea379622a 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1280,15 +1280,12 @@ extern int sysctl_perf_cpu_time_max_percent;
 
 extern void perf_sample_event_took(u64 sample_len_ns);
 
-extern int perf_proc_update_handler(struct ctl_table *table, int write,
-		void __user *buffer, size_t *lenp,
-		loff_t *ppos);
-extern int perf_cpu_time_max_percent_handler(struct ctl_table *table, int write,
-		void __user *buffer, size_t *lenp,
-		loff_t *ppos);
-
+int perf_proc_update_handler(struct ctl_table *table, int write,
+		void *buffer, size_t *lenp, loff_t *ppos);
+int perf_cpu_time_max_percent_handler(struct ctl_table *table, int write,
+		void *buffer, size_t *lenp, loff_t *ppos);
 int perf_event_max_stack_handler(struct ctl_table *table, int write,
-				 void __user *buffer, size_t *lenp, loff_t *ppos);
+		void *buffer, size_t *lenp, loff_t *ppos);
 
 /* Access to perf_event_open(2) syscall. */
 #define PERF_SECURITY_OPEN		0
diff --git a/include/linux/printk.h b/include/linux/printk.h
index e061635e0409..fcde0772ec98 100644
--- a/include/linux/printk.h
+++ b/include/linux/printk.h
@@ -189,7 +189,7 @@ extern int printk_delay_msec;
 extern int dmesg_restrict;
 
 extern int
-devkmsg_sysctl_set_loglvl(struct ctl_table *table, int write, void __user *buf,
+devkmsg_sysctl_set_loglvl(struct ctl_table *table, int write, void *buf,
 			  size_t *lenp, loff_t *ppos);
 
 extern void wake_up_klogd(void);
diff --git a/include/linux/sched/sysctl.h b/include/linux/sched/sysctl.h
index d4f6215ee03f..7b4d3a49b6c5 100644
--- a/include/linux/sched/sysctl.h
+++ b/include/linux/sched/sysctl.h
@@ -12,9 +12,8 @@ extern unsigned int  sysctl_hung_task_panic;
 extern unsigned long sysctl_hung_task_timeout_secs;
 extern unsigned long sysctl_hung_task_check_interval_secs;
 extern int sysctl_hung_task_warnings;
-extern int proc_dohung_task_timeout_secs(struct ctl_table *table, int write,
-					 void __user *buffer,
-					 size_t *lenp, loff_t *ppos);
+int proc_dohung_task_timeout_secs(struct ctl_table *table, int write,
+		void *buffer, size_t *lenp, loff_t *ppos);
 #else
 /* Avoid need for ifdefs elsewhere in the code */
 enum { sysctl_hung_task_timeout_secs = 0 };
@@ -43,8 +42,7 @@ extern __read_mostly unsigned int sysctl_sched_migration_cost;
 extern __read_mostly unsigned int sysctl_sched_nr_migrate;
 
 int sched_proc_update_handler(struct ctl_table *table, int write,
-		void __user *buffer, size_t *length,
-		loff_t *ppos);
+		void *buffer, size_t *length, loff_t *ppos);
 #endif
 
 /*
@@ -72,33 +70,21 @@ extern unsigned int sysctl_sched_autogroup_enabled;
 extern int sysctl_sched_rr_timeslice;
 extern int sched_rr_timeslice;
 
-extern int sched_rr_handler(struct ctl_table *table, int write,
-		void __user *buffer, size_t *lenp,
-		loff_t *ppos);
-
-extern int sched_rt_handler(struct ctl_table *table, int write,
-		void __user *buffer, size_t *lenp,
-		loff_t *ppos);
-
-#ifdef CONFIG_UCLAMP_TASK
-extern int sysctl_sched_uclamp_handler(struct ctl_table *table, int write,
-				       void __user *buffer, size_t *lenp,
-				       loff_t *ppos);
-#endif
-
-extern int sysctl_numa_balancing(struct ctl_table *table, int write,
-				 void __user *buffer, size_t *lenp,
-				 loff_t *ppos);
-
-extern int sysctl_schedstats(struct ctl_table *table, int write,
-				 void __user *buffer, size_t *lenp,
-				 loff_t *ppos);
+int sched_rr_handler(struct ctl_table *table, int write, void *buffer,
+		size_t *lenp, loff_t *ppos);
+int sched_rt_handler(struct ctl_table *table, int write, void *buffer,
+		size_t *lenp, loff_t *ppos);
+int sysctl_sched_uclamp_handler(struct ctl_table *table, int write,
+		void *buffer, size_t *lenp, loff_t *ppos);
+int sysctl_numa_balancing(struct ctl_table *table, int write, void *buffer,
+		size_t *lenp, loff_t *ppos);
+int sysctl_schedstats(struct ctl_table *table, int write, void *buffer,
+		size_t *lenp, loff_t *ppos);
 
 #if defined(CONFIG_ENERGY_MODEL) && defined(CONFIG_CPU_FREQ_GOV_SCHEDUTIL)
 extern unsigned int sysctl_sched_energy_aware;
-extern int sched_energy_aware_handler(struct ctl_table *table, int write,
-				 void __user *buffer, size_t *lenp,
-				 loff_t *ppos);
+int sched_energy_aware_handler(struct ctl_table *table, int write,
+		void *buffer, size_t *lenp, loff_t *ppos);
 #endif
 
 #endif /* _LINUX_SCHED_SYSCTL_H */
diff --git a/include/linux/security.h b/include/linux/security.h
index a8d9310472df..6aa229b252ce 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -211,7 +211,7 @@ struct request_sock;
 
 #ifdef CONFIG_MMU
 extern int mmap_min_addr_handler(struct ctl_table *table, int write,
-				 void __user *buffer, size_t *lenp, loff_t *ppos);
+				 void *buffer, size_t *lenp, loff_t *ppos);
 #endif
 
 /* security_inode_init_security callback function to write xattrs */
diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 36143ca40b56..f2401e45a3c2 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -44,35 +44,26 @@ struct ctl_dir;
 
 extern const int sysctl_vals[];
 
-typedef int proc_handler (struct ctl_table *ctl, int write,
-			  void __user *buffer, size_t *lenp, loff_t *ppos);
-
-extern int proc_dostring(struct ctl_table *, int,
-			 void __user *, size_t *, loff_t *);
-extern int proc_dointvec(struct ctl_table *, int,
-			 void __user *, size_t *, loff_t *);
-extern int proc_douintvec(struct ctl_table *, int,
-			 void __user *, size_t *, loff_t *);
-extern int proc_dointvec_minmax(struct ctl_table *, int,
-				void __user *, size_t *, loff_t *);
-extern int proc_douintvec_minmax(struct ctl_table *table, int write,
-				 void __user *buffer, size_t *lenp,
-				 loff_t *ppos);
-extern int proc_dointvec_jiffies(struct ctl_table *, int,
-				 void __user *, size_t *, loff_t *);
-extern int proc_dointvec_userhz_jiffies(struct ctl_table *, int,
-					void __user *, size_t *, loff_t *);
-extern int proc_dointvec_ms_jiffies(struct ctl_table *, int,
-				    void __user *, size_t *, loff_t *);
-extern int proc_doulongvec_minmax(struct ctl_table *, int,
-				  void __user *, size_t *, loff_t *);
-extern int proc_doulongvec_ms_jiffies_minmax(struct ctl_table *table, int,
-				      void __user *, size_t *, loff_t *);
-extern int proc_do_large_bitmap(struct ctl_table *, int,
-				void __user *, size_t *, loff_t *);
-extern int proc_do_static_key(struct ctl_table *table, int write,
-			      void __user *buffer, size_t *lenp,
-			      loff_t *ppos);
+typedef int proc_handler(struct ctl_table *ctl, int write, void *buffer,
+		size_t *lenp, loff_t *ppos);
+
+int proc_dostring(struct ctl_table *, int, void *, size_t *, loff_t *);
+int proc_dointvec(struct ctl_table *, int, void *, size_t *, loff_t *);
+int proc_douintvec(struct ctl_table *, int, void *, size_t *, loff_t *);
+int proc_dointvec_minmax(struct ctl_table *, int, void *, size_t *, loff_t *);
+int proc_douintvec_minmax(struct ctl_table *table, int write, void *buffer,
+		size_t *lenp, loff_t *ppos);
+int proc_dointvec_jiffies(struct ctl_table *, int, void *, size_t *, loff_t *);
+int proc_dointvec_userhz_jiffies(struct ctl_table *, int, void *, size_t *,
+		loff_t *);
+int proc_dointvec_ms_jiffies(struct ctl_table *, int, void *, size_t *,
+		loff_t *);
+int proc_doulongvec_minmax(struct ctl_table *, int, void *, size_t *, loff_t *);
+int proc_doulongvec_ms_jiffies_minmax(struct ctl_table *table, int, void *,
+		size_t *, loff_t *);
+int proc_do_large_bitmap(struct ctl_table *, int, void *, size_t *, loff_t *);
+int proc_do_static_key(struct ctl_table *table, int write, void *buffer,
+		size_t *lenp, loff_t *ppos);
 
 /*
  * Register a set of sysctl names by calling register_sysctl_table
@@ -246,7 +237,7 @@ static inline void setup_sysctl_set(struct ctl_table_set *p,
 
 #endif /* CONFIG_SYSCTL */
 
-int sysctl_max_threads(struct ctl_table *table, int write,
-		       void __user *buffer, size_t *lenp, loff_t *ppos);
+int sysctl_max_threads(struct ctl_table *table, int write, void *buffer,
+		size_t *lenp, loff_t *ppos);
 
 #endif /* _LINUX_SYSCTL_H */
diff --git a/include/linux/timer.h b/include/linux/timer.h
index 0dc19a8c39c9..07910ae5ddd9 100644
--- a/include/linux/timer.h
+++ b/include/linux/timer.h
@@ -201,8 +201,7 @@ struct ctl_table;
 
 extern unsigned int sysctl_timer_migration;
 int timer_migration_handler(struct ctl_table *table, int write,
-			    void __user *buffer, size_t *lenp,
-			    loff_t *ppos);
+			    void *buffer, size_t *lenp, loff_t *ppos);
 #endif
 
 unsigned long __round_jiffies(unsigned long j, int cpu);
diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
index 292485f3d24d..cb507151710f 100644
--- a/include/linux/vmstat.h
+++ b/include/linux/vmstat.h
@@ -16,8 +16,8 @@ extern int sysctl_stat_interval;
 #define DISABLE_NUMA_STAT   0
 extern int sysctl_vm_numa_stat;
 DECLARE_STATIC_KEY_TRUE(vm_numa_stat_key);
-extern int sysctl_vm_numa_stat_handler(struct ctl_table *table,
-		int write, void __user *buffer, size_t *length, loff_t *ppos);
+int sysctl_vm_numa_stat_handler(struct ctl_table *table, int write,
+		void *buffer, size_t *length, loff_t *ppos);
 #endif
 
 struct reclaim_stat {
@@ -274,8 +274,8 @@ void cpu_vm_stats_fold(int cpu);
 void refresh_zone_stat_thresholds(void);
 
 struct ctl_table;
-int vmstat_refresh(struct ctl_table *, int write,
-		   void __user *buffer, size_t *lenp, loff_t *ppos);
+int vmstat_refresh(struct ctl_table *, int write, void *buffer, size_t *lenp,
+		loff_t *ppos);
 
 void drain_zonestat(struct zone *zone, struct per_cpu_pageset *);
 
diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index a19d845dd7eb..f8a7e1a850fb 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -362,24 +362,18 @@ extern int vm_highmem_is_dirtyable;
 extern int block_dump;
 extern int laptop_mode;
 
-extern int dirty_background_ratio_handler(struct ctl_table *table, int write,
-		void __user *buffer, size_t *lenp,
-		loff_t *ppos);
-extern int dirty_background_bytes_handler(struct ctl_table *table, int write,
-		void __user *buffer, size_t *lenp,
-		loff_t *ppos);
-extern int dirty_ratio_handler(struct ctl_table *table, int write,
-		void __user *buffer, size_t *lenp,
-		loff_t *ppos);
-extern int dirty_bytes_handler(struct ctl_table *table, int write,
-		void __user *buffer, size_t *lenp,
-		loff_t *ppos);
+int dirty_background_ratio_handler(struct ctl_table *table, int write,
+		void *buffer, size_t *lenp, loff_t *ppos);
+int dirty_background_bytes_handler(struct ctl_table *table, int write,
+		void *buffer, size_t *lenp, loff_t *ppos);
+int dirty_ratio_handler(struct ctl_table *table, int write,
+		void *buffer, size_t *lenp, loff_t *ppos);
+int dirty_bytes_handler(struct ctl_table *table, int write,
+		void *buffer, size_t *lenp, loff_t *ppos);
 int dirtytime_interval_handler(struct ctl_table *table, int write,
-			       void __user *buffer, size_t *lenp, loff_t *ppos);
-
-struct ctl_table;
-int dirty_writeback_centisecs_handler(struct ctl_table *, int,
-				      void __user *, size_t *, loff_t *);
+		void *buffer, size_t *lenp, loff_t *ppos);
+int dirty_writeback_centisecs_handler(struct ctl_table *table, int write,
+		void *buffer, size_t *lenp, loff_t *ppos);
 
 void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty);
 unsigned long wb_calc_thresh(struct bdi_writeback *wb, unsigned long thresh);