Merge branch 'core/printk' into tracing/ftrace

[sfrench/cifs-2.6.git] / include / linux / kernel.h

diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 7fa371898e3e76d8e1af870f049844ff71bea931..7aef15c4645e02516d629e8246d9cb23d9ddece0 100644 (file)
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -242,6 +242,19 @@ extern struct ratelimit_state printk_ratelimit_state;
 extern int printk_ratelimit(void);
 extern bool printk_timed_ratelimit(unsigned long *caller_jiffies,
                                   unsigned int interval_msec);
+
+/*
+ * Print a one-time message (analogous to WARN_ONCE() et al):
+ */
+#define printk_once(x...) ({                   \
+       static int __print_once = 1;            \
+                                               \
+       if (__print_once) {                     \
+               __print_once = 0;               \
+               printk(x);                      \
+       }                                       \
+})
+
 #else
 static inline int vprintk(const char *s, va_list args)
        __attribute__ ((format (printf, 1, 0)));
@@ -253,6 +266,10 @@ static inline int printk_ratelimit(void) { return 0; }
 static inline bool printk_timed_ratelimit(unsigned long *caller_jiffies, \
                                          unsigned int interval_msec)   \
                { return false; }
+
+/* No effect, but we still get type checking even in the !PRINTK case: */
+#define printk_once(x...) printk(x)
+
 #endif
 
 extern int printk_needs_cpu(int cpu);
@@ -367,6 +384,91 @@ static inline char *pack_hex_byte(char *buf, u8 byte)
        ({ if (0) printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__); 0; })
 #endif
 
+/*
+ * General tracing related utility functions - trace_printk(),
+ * tracing_on/tracing_off and tracing_start()/tracing_stop
+ *
+ * Use tracing_on/tracing_off when you want to quickly turn on or off
+ * tracing. It simply enables or disables the recording of the trace events.
+ * This also corresponds to the user space debugfs/tracing/tracing_on
+ * file, which gives a means for the kernel and userspace to interact.
+ * Place a tracing_off() in the kernel where you want tracing to end.
+ * From user space, examine the trace, and then echo 1 > tracing_on
+ * to continue tracing.
+ *
+ * tracing_stop/tracing_start has slightly more overhead. It is used
+ * by things like suspend to ram where disabling the recording of the
+ * trace is not enough, but tracing must actually stop because things
+ * like calling smp_processor_id() may crash the system.
+ *
+ * Most likely, you want to use tracing_on/tracing_off.
+ */
+#ifdef CONFIG_RING_BUFFER
+void tracing_on(void);
+void tracing_off(void);
+/* trace_off_permanent stops recording with no way to bring it back */
+void tracing_off_permanent(void);
+int tracing_is_on(void);
+#else
+static inline void tracing_on(void) { }
+static inline void tracing_off(void) { }
+static inline void tracing_off_permanent(void) { }
+static inline int tracing_is_on(void) { return 0; }
+#endif
+#ifdef CONFIG_TRACING
+extern void tracing_start(void);
+extern void tracing_stop(void);
+extern void ftrace_off_permanent(void);
+
+extern void
+ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3);
+
+/**
+ * trace_printk - printf formatting in the ftrace buffer
+ * @fmt: the printf format for printing
+ *
+ * Note: __trace_printk is an internal function for trace_printk and
+ *       the @ip is passed in via the trace_printk macro.
+ *
+ * This function allows a kernel developer to debug fast path sections
+ * that printk is not appropriate for. By scattering in various
+ * printk like tracing in the code, a developer can quickly see
+ * where problems are occurring.
+ *
+ * This is intended as a debugging tool for the developer only.
+ * Please refrain from leaving trace_printks scattered around in
+ * your code.
+ */
+# define trace_printk(fmt...) __trace_printk(_THIS_IP_, fmt)
+extern int
+__trace_printk(unsigned long ip, const char *fmt, ...)
+       __attribute__ ((format (printf, 2, 3)));
+# define ftrace_vprintk(fmt, ap) __trace_printk(_THIS_IP_, fmt, ap)
+extern int
+__ftrace_vprintk(unsigned long ip, const char *fmt, va_list ap);
+extern void ftrace_dump(void);
+#else
+static inline void
+ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3) { }
+static inline int
+trace_printk(const char *fmt, ...) __attribute__ ((format (printf, 1, 2)));
+
+static inline void tracing_start(void) { }
+static inline void tracing_stop(void) { }
+static inline void ftrace_off_permanent(void) { }
+static inline int
+trace_printk(const char *fmt, ...)
+{
+       return 0;
+}
+static inline int
+ftrace_vprintk(const char *fmt, va_list ap)
+{
+       return 0;
+}
+static inline void ftrace_dump(void) { }
+#endif
+
 /*
  *      Display an IP address in readable format.
  */