[Intel-gfx] [PATCH i-g-t 3/5] i915: Exercise preemption timeout controls in sysfs

[Chris Wilson]

Quoting Andi Shyti (2020-02-28 23:51:24)
> > > > +void dyn_sysfs_engines(int i915, int engines, const char *file,
> > > > +                    void (*test)(int, int))
> > > > +{
> > > > +     char buf[512];
> > > > +     int len;
> > > > +
> > > > +     lseek(engines, 0, SEEK_SET);
> > > > +     while ((len = syscall(SYS_getdents64, engines, buf, sizeof(buf))) > 0) {
> > > > +             void *ptr = buf;
> > > > +
> > > > +             while (len) {
> > > > +                     struct linux_dirent64 {
> > > > +                             ino64_t        d_ino;
> > > > +                             off64_t        d_off;
> > > > +                             unsigned short d_reclen;
> > > > +                             unsigned char  d_type;
> > > > +                             char           d_name[];
> > > > +                     } *de = ptr;
> > > 
> > > what is the need for having your own linux_dirent64?
> > 
> > fdopendir() takes ownership of the fd, preventing reuse. And
> > fdopendir(dup()) is getting ridiculous.
> 
> why not using dirent64?

It's still the same problem that it takes a DIR, assuming ownership of
the fd. Why using linux_dirent64 because the manpage says so -- if you
are going to use the syscall, you need to match it's calling
conventions, not a middleman's.
-Chris