On Wed, Aug 15, 2007 at 02:37:41PM +0800, Fengguang Wu wrote: > static void *ct_seq_next(struct seq_file *s, void *v, loff_t *pos) > { > loff_t *spos = (loff_t *) v; > *pos = ++(*spos); > return spos; > } > > I mean 'pos' is sometimes increased in ct_seq_next(), and sometimes from > seq_file.c/seq_read(), too. Thus we cannot reliably do this: > > *pos = (*spos) + some_variable_offset;
Of course we can. These guys can be sparse - note that ->start() takes a pointer, and for a good reason. ->start(m, p, pos) should get the first entry with offset >= *pos (or NULL if we are done) and set *pos accordingly. That m->index++ is "we are done with the partial, step just past it, so that ->start() will pick the first real entry after it the next time it's called". For dense case we don't need to update *pos in ->start() - either we already have one with offset == *pos (and no update is needed), or we are finished and should return NULL. However, we have every right to live with sparse offsets; prototype of ->start() had been done the way it's done exactly to allow that kind of use. - 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/