Merge git://git.kernel.org/pub/scm/linux/kernel/git/bart/ide-2.6

[pandora-kernel.git] / kernel / trace / trace_syscalls.c

diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index c5fc1d8..5e57964 100644 (file)
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -1,13 +1,17 @@
+#include <trace/syscall.h>
 #include <linux/kernel.h>
-#include <linux/ftrace.h>
 #include <asm/syscall.h>
 
 #include "trace_output.h"
 #include "trace.h"
 
-static atomic_t refcount;
+/* Keep a counter of the syscall tracing users */
+static int refcount;
 
-/* Our two options */
+/* Prevent from races on thread flags toggling */
+static DEFINE_MUTEX(syscall_trace_lock);
+
+/* Option to display the parameters types */
 enum {
        TRACE_SYSCALLS_OPT_TYPES = 0x1,
 };
@@ -18,7 +22,7 @@ static struct tracer_opt syscalls_opts[] = {
 };
 
 static struct tracer_flags syscalls_flags = {
-       .val = 0, /* By default: no args types */
+       .val = 0, /* By default: no parameters types */
        .opts = syscalls_opts
 };
 
@@ -96,9 +100,11 @@ void start_ftrace_syscalls(void)
        unsigned long flags;
        struct task_struct *g, *t;
 
+       mutex_lock(&syscall_trace_lock);
+
        /* Don't enable the flag on the tasks twice */
-       if (atomic_inc_return(&refcount) != 1)
-               return;
+       if (++refcount != 1)
+               goto unlock;
 
        arch_init_ftrace_syscalls();
        read_lock_irqsave(&tasklist_lock, flags);
@@ -108,6 +114,9 @@ void start_ftrace_syscalls(void)
        } while_each_thread(g, t);
 
        read_unlock_irqrestore(&tasklist_lock, flags);
+
+unlock:
+       mutex_unlock(&syscall_trace_lock);
 }
 
 void stop_ftrace_syscalls(void)
@@ -115,9 +124,11 @@ void stop_ftrace_syscalls(void)
        unsigned long flags;
        struct task_struct *g, *t;
 
+       mutex_lock(&syscall_trace_lock);
+
        /* There are perhaps still some users */
-       if (atomic_dec_return(&refcount))
-               return;
+       if (--refcount)
+               goto unlock;
 
        read_lock_irqsave(&tasklist_lock, flags);
 
@@ -126,6 +137,9 @@ void stop_ftrace_syscalls(void)
        } while_each_thread(g, t);
 
        read_unlock_irqrestore(&tasklist_lock, flags);
+
+unlock:
+       mutex_unlock(&syscall_trace_lock);
 }
 
 void ftrace_syscall_enter(struct pt_regs *regs)
@@ -135,12 +149,9 @@ void ftrace_syscall_enter(struct pt_regs *regs)
        struct ring_buffer_event *event;
        int size;
        int syscall_nr;
-       int cpu;
 
        syscall_nr = syscall_get_nr(current, regs);
 
-       cpu = raw_smp_processor_id();
-
        sys_data = syscall_nr_to_meta(syscall_nr);
        if (!sys_data)
                return;
@@ -166,12 +177,9 @@ void ftrace_syscall_exit(struct pt_regs *regs)
        struct syscall_metadata *sys_data;
        struct ring_buffer_event *event;
        int syscall_nr;
-       int cpu;
 
        syscall_nr = syscall_get_nr(current, regs);
 
-       cpu = raw_smp_processor_id();
-
        sys_data = syscall_nr_to_meta(syscall_nr);
        if (!sys_data)
                return;