On Wed, Dec 04, 2019 at 09:26:40AM -0500, Steven Rostedt wrote:
> On Tue, 26 Nov 2019 15:19:34 +0300
> Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote:
>
> > Smatch complains that "ret" could be uninitialized if we don't enter the
> > loop. I don't know if that's possible, but it's nicer to return a
> > literal zero instead.
> >
> > Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> > ---
> > kernel/trace/trace_syscalls.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
> > index 73140d80dd46..63528f458826 100644
> > --- a/kernel/trace/trace_syscalls.c
> > +++ b/kernel/trace/trace_syscalls.c
> > @@ -286,7 +286,7 @@ static int __init syscall_enter_define_fields(struct trace_event_call *call)
> > offset += sizeof(unsigned long);
> > }
> >
> > - return ret;
> > + return 0;
> > }
> >
> > static void ftrace_syscall_enter(void *data, struct pt_regs *regs, long id)
>
> The current code has this:
>
> static int __init syscall_enter_define_fields(struct trace_event_call *call)
> {
> struct syscall_trace_enter trace;
> struct syscall_metadata *meta = call->data;
> int ret;
> int i;
> int offset = offsetof(typeof(trace), args);
>
> ret = trace_define_field(call, SYSCALL_FIELD(int, nr, __syscall_nr),
> FILTER_OTHER);
In linux-next this ret = trace_define_field() assignment is removed.
That was commit 60fdad00827c ("ftrace: Rework event_create_dir()").
> if (ret)
> return ret;
>
> for (i = 0; i < meta->nb_args; i++) {
> ret = trace_define_field(call, meta->types[i],
> meta->args[i], offset,
> sizeof(unsigned long), 0,
> FILTER_OTHER);
> offset += sizeof(unsigned long);
> }
>
> return ret;
> }
>
>
> How can ret possibly be uninitialized?
I should have written this commit more carefully and verified whether
meta->nb_args can actually be zero instead of just assuming it was a
false positive...
regards,
dan carpenter
