Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...

Pull perf fixes from Ingo Molnar:
 "Misc minor fixes mostly related to tracing"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  s390: Fix a header dependencies related build error
  tracing: update documentation of snapshot utility
  tracing: Do not return EINVAL in snapshot when not allocated
  tracing: Add help of snapshot feature when snapshot is empty
  ftrace: Update the kconfig for DYNAMIC_FTRACE

diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt
index 53d6a3c51d875771fc2966c9917aec13b17f53c6..a372304aef10a378bc00440053c0fe4028eac566 100644 (file)
--- a/Documentation/trace/ftrace.txt
+++ b/Documentation/trace/ftrace.txt
@@ -1873,7 +1873,7 @@ feature:
 
        status\input  |     0      |     1      |    else    |
        --------------+------------+------------+------------+
-       not allocated |(do nothing)| alloc+swap |   EINVAL   |
+       not allocated |(do nothing)| alloc+swap |(do nothing)|
        --------------+------------+------------+------------+
        allocated     |    free    |    swap    |   clear    |
        --------------+------------+------------+------------+

diff --git a/arch/s390/include/asm/cpu_mf.h b/arch/s390/include/asm/cpu_mf.h
index f1eddd150dd7e782876ed8faff25a6d004b3f841..c879fad404c8d36d73aff75ea1174df65374061b 100644 (file)
--- a/arch/s390/include/asm/cpu_mf.h
+++ b/arch/s390/include/asm/cpu_mf.h
@@ -12,6 +12,7 @@
 #ifndef _ASM_S390_CPU_MF_H
 #define _ASM_S390_CPU_MF_H
 
+#include <linux/errno.h>
 #include <asm/facility.h>
 
 #define CPU_MF_INT_SF_IAE      (1 << 31)       /* invalid entry address */

diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 192473b22799032c5cb013868f778ad4bc30626a..fc382d6e2765d4a454a85aa5591c8edc452dccfb 100644 (file)
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -414,24 +414,28 @@ config PROBE_EVENTS
        def_bool n
 
 config DYNAMIC_FTRACE
-       bool "enable/disable ftrace tracepoints dynamically"
+       bool "enable/disable function tracing dynamically"
        depends on FUNCTION_TRACER
        depends on HAVE_DYNAMIC_FTRACE
        default y
        help
-          This option will modify all the calls to ftrace dynamically
-         (will patch them out of the binary image and replace them
-         with a No-Op instruction) as they are called. A table is
-         created to dynamically enable them again.
+         This option will modify all the calls to function tracing
+         dynamically (will patch them out of the binary image and
+         replace them with a No-Op instruction) on boot up. During
+         compile time, a table is made of all the locations that ftrace
+         can function trace, and this table is linked into the kernel
+         image. When this is enabled, functions can be individually
+         enabled, and the functions not enabled will not affect
+         performance of the system.
+
+         See the files in /sys/kernel/debug/tracing:
+           available_filter_functions
+           set_ftrace_filter
+           set_ftrace_notrace
 
          This way a CONFIG_FUNCTION_TRACER kernel is slightly larger, but
          otherwise has native performance as long as no tracing is active.
 
-         The changes to the code are done by a kernel thread that
-         wakes up once a second and checks to see if any ftrace calls
-         were made. If so, it runs stop_machine (stops all CPUS)
-         and modifies the code to jump over the call to ftrace.
-
 config DYNAMIC_FTRACE_WITH_REGS
        def_bool y
        depends on DYNAMIC_FTRACE

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index c2e2c23103742e3a3e53cf7b318aa0c804f5e1a8..1f835a83cb2c4c74b13b0c8641ce648a75591ae6 100644 (file)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2400,6 +2400,27 @@ static void test_ftrace_alive(struct seq_file *m)
        seq_printf(m, "#          MAY BE MISSING FUNCTION EVENTS\n");
 }
 
+#ifdef CONFIG_TRACER_MAX_TRACE
+static void print_snapshot_help(struct seq_file *m, struct trace_iterator *iter)
+{
+       if (iter->trace->allocated_snapshot)
+               seq_printf(m, "#\n# * Snapshot is allocated *\n#\n");
+       else
+               seq_printf(m, "#\n# * Snapshot is freed *\n#\n");
+
+       seq_printf(m, "# Snapshot commands:\n");
+       seq_printf(m, "# echo 0 > snapshot : Clears and frees snapshot buffer\n");
+       seq_printf(m, "# echo 1 > snapshot : Allocates snapshot buffer, if not already allocated.\n");
+       seq_printf(m, "#                      Takes a snapshot of the main buffer.\n");
+       seq_printf(m, "# echo 2 > snapshot : Clears snapshot buffer (but does not allocate)\n");
+       seq_printf(m, "#                      (Doesn't have to be '2' works with any number that\n");
+       seq_printf(m, "#                       is not a '0' or '1')\n");
+}
+#else
+/* Should never be called */
+static inline void print_snapshot_help(struct seq_file *m, struct trace_iterator *iter) { }
+#endif
+
 static int s_show(struct seq_file *m, void *v)
 {
        struct trace_iterator *iter = v;
@@ -2411,7 +2432,9 @@ static int s_show(struct seq_file *m, void *v)
                        seq_puts(m, "#\n");
                        test_ftrace_alive(m);
                }
-               if (iter->trace && iter->trace->print_header)
+               if (iter->snapshot && trace_empty(iter))
+                       print_snapshot_help(m, iter);
+               else if (iter->trace && iter->trace->print_header)
                        iter->trace->print_header(m);
                else
                        trace_default_header(m);
@@ -4144,8 +4167,6 @@ tracing_snapshot_write(struct file *filp, const char __user *ubuf, size_t cnt,
        default:
                if (current_trace->allocated_snapshot)
                        tracing_reset_online_cpus(&max_tr);
-               else
-                       ret = -EINVAL;
                break;
        }