Re: [PATCHv3] Introduced new tracing mode KCOV_MODE_UNIQUE.

[Alexander Lochmann <info@xxxxxxxxxxxxxxxxxxxxx>]

On 27.03.21 15:56, Andrey Konovalov wrote:
> > @@ -213,9 +223,10 @@ static void notrace write_comp_data(u64 type, u64 arg1, u64 arg2, u64 ip)
> >          struct task_struct *t;
> >          u64 *area;
> >          u64 count, start_index, end_pos, max_pos;
> > +       unsigned int mode;
> >
> >          t = current;
> > -       if (!check_kcov_mode(KCOV_MODE_TRACE_CMP, t))
> > +       if (!check_kcov_mode(KCOV_MODE_TRACE_CMP, t, &mode))
> >                  return;
>
> mode isn't used here, right? No need for it then.
No, it's not. However, check_kcov_mode() needs it. Dmitry suggested 
passing a pointer to check_kcov_mode(), and let the optimizer do the rest.
> > @@ -562,12 +576,14 @@ static int kcov_ioctl_locked(struct kcov *kcov, unsigned int cmd,
> >   {
> >          struct task_struct *t;
> >          unsigned long size, unused;
> > -       int mode, i;
> > +       int mode, i, text_size, ret = 0;
> >          struct kcov_remote_arg *remote_arg;
> >          struct kcov_remote *remote;
> >          unsigned long flags;
> >
> >          switch (cmd) {
> > +       case KCOV_INIT_UNIQUE:
> > +               fallthrough;
> >          case KCOV_INIT_TRACE:
> >                  /*
> >                   * Enable kcov in trace mode and setup buffer size.
> > @@ -581,11 +597,42 @@ static int kcov_ioctl_locked(struct kcov *kcov, unsigned int cmd,
> >                   * that must not overflow.
> >                   */
> >                  size = arg;
> > -               if (size < 2 || size > INT_MAX / sizeof(unsigned long))
> > -                       return -EINVAL;
> > -               kcov->size = size;
> > -               kcov->mode = KCOV_MODE_INIT;
> > -               return 0;
> > +               if (cmd == KCOV_INIT_UNIQUE) {
>
> Let's put this code under KCOV_INIT_UNIQUE in the switch. This
> internal if only saves duplicating two lines of code, which isn't
> worth it.
So. Shall I skip the fallthrough and move 'my' code upwards?

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Alexander Lochmann                PGP key: 0xBC3EF6FD
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