On Fri, Jul 20, 2018 at 12:29:52PM +0200, Vlastimil Babka wrote: > single_open() currently allocates seq_operations with kmalloc(). This is > suboptimal, because that's four pointers, of which three are constant, and > only the 'show' op differs. We also have to be careful to use single_release() > to avoid leaking the ops structure. > > Instead of this we can have a fixed single_show() function and constant ops > structure for these seq_files. We can store the pointer to the 'show' op as > a new field of struct seq_file. That's also not terribly elegant, because the > field is there also for non-single_open() seq files, but it's a single pointer > in an already existing (and already relatively large) structure instead of > an extra kmalloc of four pointers, so the tradeoff is OK.
... except that piling indirect calls is costly and ->show() is called a lot more than open() is.
