On Fri, 22 Aug 2014 17:28:22 +0300 Andreea-Cristina Bernat <[email protected]> wrote:
> The uses of "rcu_assign_pointer()" are NULLing out the pointers. > According to RCU_INIT_POINTER()'s block comment: > "1. This use of RCU_INIT_POINTER() is NULLing out the pointer" > it is better to use it instead of rcu_assign_pointer() because it has a > smaller overhead. > > The following Coccinelle semantic patch was used: > @@ > @@ > > - rcu_assign_pointer > + RCU_INIT_POINTER > (..., NULL) I guess I can add this. It's a very slow path thus it isn't critical. Although, I hate the name. Perhaps we should add another macro called RCU_CLEAR_POINTER() or something that just nulls it. That way it documents the use. To me, INIT means the pointer is being initialized, where in reality it's just being cleared. I guess one could argue that the pointer is being "re-initialized". Thanks! -- Steve > > Signed-off-by: Andreea-Cristina Bernat <[email protected]> > --- > kernel/trace/trace_syscalls.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c > index 759d5e0..4dc8b79 100644 > --- a/kernel/trace/trace_syscalls.c > +++ b/kernel/trace/trace_syscalls.c > @@ -425,7 +425,7 @@ static void unreg_event_syscall_enter(struct > ftrace_event_file *file, > return; > mutex_lock(&syscall_trace_lock); > tr->sys_refcount_enter--; > - rcu_assign_pointer(tr->enter_syscall_files[num], NULL); > + RCU_INIT_POINTER(tr->enter_syscall_files[num], NULL); > if (!tr->sys_refcount_enter) > unregister_trace_sys_enter(ftrace_syscall_enter, tr); > mutex_unlock(&syscall_trace_lock); > @@ -463,7 +463,7 @@ static void unreg_event_syscall_exit(struct > ftrace_event_file *file, > return; > mutex_lock(&syscall_trace_lock); > tr->sys_refcount_exit--; > - rcu_assign_pointer(tr->exit_syscall_files[num], NULL); > + RCU_INIT_POINTER(tr->exit_syscall_files[num], NULL); > if (!tr->sys_refcount_exit) > unregister_trace_sys_exit(ftrace_syscall_exit, tr); > mutex_unlock(&syscall_trace_lock); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
