trace: fix an incorrect __user annotation on stack_trace_sysctl

No user pointers for sysctls anymore.

Fixes: 3292739 ("sysctl: pass kernel pointers to ->proc_handler")
Reported-by: build test robot <lkp@intel.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Author: Christoph Hellwig

include/linux/ftrace.h

@@ -319,9 +319,8 @@ static inline void arch_ftrace_set_direct_caller(struct pt_regs *regs,
 
 extern int stack_tracer_enabled;
 
-int stack_trace_sysctl(struct ctl_table *table, int write,
-		       void __user *buffer, size_t *lenp,
-		       loff_t *ppos);
+int stack_trace_sysctl(struct ctl_table *table, int write, void *buffer,
+		       size_t *lenp, loff_t *ppos);
 
 /* DO NOT MODIFY THIS VARIABLE DIRECTLY! */
 DECLARE_PER_CPU(int, disable_stack_tracer);

kernel/trace/trace_stack.c

@@ -515,9 +515,8 @@ static const struct file_operations stack_trace_filter_fops = {
 #endif /* CONFIG_DYNAMIC_FTRACE */
 
 int
-stack_trace_sysctl(struct ctl_table *table, int write,
-		   void __user *buffer, size_t *lenp,
-		   loff_t *ppos)
+stack_trace_sysctl(struct ctl_table *table, int write, void *buffer,
+		   size_t *lenp, loff_t *ppos)
 {
 	int was_enabled;
 	int ret;