Messages in this thread | | | Date | Fri, 19 Jun 2009 16:31:09 +0800 | From | Li Zefan <> | Subject | Re: [PATCH 4/7] add syscall tracepoints |
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> /* > * A syscall entry in the ftrace syscalls array. > diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c > index 1ef5d3a..5b34ff9 100644 > --- a/kernel/tracepoint.c > +++ b/kernel/tracepoint.c > @@ -24,6 +24,7 @@ > #include <linux/tracepoint.h> > #include <linux/err.h> > #include <linux/slab.h> > +#include <linux/sched.h> > > extern struct tracepoint __start___tracepoints[]; > extern struct tracepoint __stop___tracepoints[]; > @@ -577,3 +578,40 @@ static int init_tracepoints(void) > __initcall(init_tracepoints); > > #endif /* CONFIG_MODULES */ > + > +DEFINE_MUTEX(regfunc_mutex);
static?
> +int sys_tracepoint_refcount;
static?
and atomic_t should be fine as Frederic pointed out.
> + > +void syscall_regfunc(void) > +{ > + unsigned long flags; > + struct task_struct *g, *t; > + > + mutex_lock(®func_mutex); > + if (!sys_tracepoint_refcount) { > + read_lock_irqsave(&tasklist_lock, flags); > + do_each_thread(g, t) { > + set_tsk_thread_flag(t, TIF_SYSCALL_FTRACE); > + } while_each_thread(g, t); > + read_unlock_irqrestore(&tasklist_lock, flags); > + } > + sys_tracepoint_refcount++; > + mutex_unlock(®func_mutex); > +} > + > +void syscall_unregfunc(void) > +{ > + unsigned long flags; > + struct task_struct *g, *t; > + > + mutex_lock(®func_mutex); > + sys_tracepoint_refcount--; > + if (!sys_tracepoint_refcount) { > + read_lock_irqsave(&tasklist_lock, flags); > + do_each_thread(g, t) { > + clear_tsk_thread_flag(t, TIF_SYSCALL_FTRACE); > + } while_each_thread(g, t); > + read_unlock_irqrestore(&tasklist_lock, flags); > + } > + mutex_unlock(®func_mutex); > +}
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