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>

8 files changed, 28 insertions, 26 deletions

diff --git a/arch/arm/include/asm/ftrace.h b/arch/arm/include/asm/ftrace.h
index d4c24a7a9280..3f3a1d1508ea 100644
--- a/arch/arm/include/asm/ftrace.h
+++ b/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
diff --git a/arch/powerpc/include/asm/ftrace.h b/arch/powerpc/include/asm/ftrace.h
index 7652755dc000..1cd72700fbc0 100644
--- a/arch/powerpc/include/asm/ftrace.h
+++ b/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
diff --git a/arch/sh/include/asm/ftrace.h b/arch/sh/include/asm/ftrace.h
index cdf2cb0b9ffe..31ada0370cb6 100644
--- a/arch/sh/include/asm/ftrace.h
+++ b/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__
diff --git a/arch/sparc/include/asm/ftrace.h b/arch/sparc/include/asm/ftrace.h
index 33a95feeb137..62055ac0496e 100644
--- a/arch/sparc/include/asm/ftrace.h
+++ b/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
diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
index f2ed6b704a75..a23468194b8c 100644
--- a/arch/x86/include/asm/ftrace.h
+++ b/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 */
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 6685b0fc1b44..69149337f2fe 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/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)
 {
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 703eb53cfa2b..22240dfe912e 100644
--- a/include/linux/ftrace.h
+++ b/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
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index bc36febc0771..7f86067d760c 100644
--- a/kernel/trace/trace.c
+++ b/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);