ftrace: nmi safe code clean ups

Impact: cleanup

This patch cleans up the NMI safe code for dynamic ftrace as suggested
by Andrew Morton.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/arm/include/asm/ftrace.h

@@ -2,8 +2,8 @@
 #define _ASM_ARM_FTRACE
 
 #ifndef __ASSEMBLY__
-#define ftrace_nmi_enter()	do { } while (0)
-#define ftrace_nmi_exit()	do { } while (0)
+static inline void ftrace_nmi_enter(void) { }
+static inline void ftrace_nmi_exit(void) { }
 #endif
 
 #ifdef CONFIG_FUNCTION_TRACER

arch/powerpc/include/asm/ftrace.h

@@ -2,8 +2,8 @@
 #define _ASM_POWERPC_FTRACE
 
 #ifndef __ASSEMBLY__
-#define ftrace_nmi_enter()	do { } while (0)
-#define ftrace_nmi_exit()	do { } while (0)
+static inline void ftrace_nmi_enter(void) { }
+static inline void ftrace_nmi_exit(void) { }
 #endif
 
 #ifdef CONFIG_FUNCTION_TRACER

arch/sh/include/asm/ftrace.h

@@ -2,8 +2,8 @@
 #define __ASM_SH_FTRACE_H
 
 #ifndef __ASSEMBLY__
-#define ftrace_nmi_enter()	do { } while (0)
-#define ftrace_nmi_exit()	do { } while (0)
+static inline void ftrace_nmi_enter(void) { }
+static inline void ftrace_nmi_exit(void) { }
 #endif
 
 #ifndef __ASSEMBLY__

arch/sparc/include/asm/ftrace.h

@@ -2,8 +2,8 @@
 #define _ASM_SPARC64_FTRACE
 
 #ifndef __ASSEMBLY__
-#define ftrace_nmi_enter()	do { } while (0)
-#define ftrace_nmi_exit()	do { } while (0)
+static inline void ftrace_nmi_enter(void) { }
+static inline void ftrace_nmi_exit(void) { }
 #endif
 
 #ifdef CONFIG_MCOUNT

arch/x86/include/asm/ftrace.h

@@ -22,16 +22,16 @@ static inline unsigned long ftrace_call_adjust(unsigned long addr)
 extern void ftrace_nmi_enter(void);
 extern void ftrace_nmi_exit(void);
 #else
-#define ftrace_nmi_enter()	do { } while (0)
-#define ftrace_nmi_exit()	do { } while (0)
-#endif
+static inline void ftrace_nmi_enter(void) { }
+static inline void ftrace_nmi_exit(void) { }
 #endif
+#endif /* __ASSEMBLY__ */
 
 #else /* CONFIG_FUNCTION_TRACER */
 
 #ifndef __ASSEMBLY__
-#define ftrace_nmi_enter()	do { } while (0)
-#define ftrace_nmi_exit()	do { } while (0)
+static inline void ftrace_nmi_enter(void) { }
+static inline void ftrace_nmi_exit(void) { }
 #endif
 
 #endif /* CONFIG_FUNCTION_TRACER */

arch/x86/kernel/ftrace.c

@@ -67,7 +67,7 @@ unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr)
  *
  * Two buffers are added: An IP buffer and a "code" buffer.
  *
- * 1) Put in the instruction pointer into the IP buffer
+ * 1) Put the instruction pointer into the IP buffer
  *    and the new code into the "code" buffer.
  * 2) Set a flag that says we are modifying code
  * 3) Wait for any running NMIs to finish.
@@ -85,14 +85,14 @@ unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr)
  * are the same as what exists.
  */
 
-static atomic_t in_nmi;
-static int mod_code_status;
-static int mod_code_write;
-static void *mod_code_ip;
-static void *mod_code_newcode;
+static atomic_t in_nmi = ATOMIC_INIT(0);
+static int mod_code_status;		/* holds return value of text write */
+static int mod_code_write;		/* set when NMI should do the write */
+static void *mod_code_ip;		/* holds the IP to write to */
+static void *mod_code_newcode;		/* holds the text to write to the IP */
 
-static int nmi_wait_count;
-static atomic_t nmi_update_count;
+static unsigned nmi_wait_count;
+static atomic_t nmi_update_count = ATOMIC_INIT(0);
 
 int ftrace_arch_read_dyn_info(char *buf, int size)
 {

include/linux/ftrace.h

@@ -74,6 +74,9 @@ extern void ftrace_caller(void);
 extern void ftrace_call(void);
 extern void mcount_call(void);
 
+/* May be defined in arch */
+extern int ftrace_arch_read_dyn_info(char *buf, int size);
+
 /**
  * ftrace_modify_code - modify code segment
  * @ip: the address of the code segment

kernel/trace/trace.c

@@ -2815,10 +2815,6 @@ static struct file_operations tracing_mark_fops = {
 
 #ifdef CONFIG_DYNAMIC_FTRACE
 
-#define DYN_INFO_BUF_SIZE 1023
-static char ftrace_dyn_info_buffer[DYN_INFO_BUF_SIZE+1];
-static DEFINE_MUTEX(dyn_info_mutex);
-
 int __weak ftrace_arch_read_dyn_info(char *buf, int size)
 {
 	return 0;
@@ -2828,14 +2824,17 @@ static ssize_t
 tracing_read_dyn_info(struct file *filp, char __user *ubuf,
 		  size_t cnt, loff_t *ppos)
 {
+	static char ftrace_dyn_info_buffer[1024];
+	static DEFINE_MUTEX(dyn_info_mutex);
 	unsigned long *p = filp->private_data;
 	char *buf = ftrace_dyn_info_buffer;
+	int size = ARRAY_SIZE(ftrace_dyn_info_buffer);
 	int r;
 
 	mutex_lock(&dyn_info_mutex);
 	r = sprintf(buf, "%ld ", *p);
 
-	r += ftrace_arch_read_dyn_info(buf+r, DYN_INFO_BUF_SIZE-r);
+	r += ftrace_arch_read_dyn_info(buf+r, (size-1)-r);
 	buf[r++] = '\n';
 
 	r = simple_read_from_buffer(ubuf, cnt, ppos, buf, r);