On Mon, Jun 20, 2022 at 04:19:31AM +0000, David Laight wrote: > I really think that is a bad idea. > printk() already uses a lot of stack, anything doing a recursive > call is just making that worse. > Especially since these calls can often be in error paths > which are not often tested and can already be on deep stacks. So it seems this is something you never actually checked, and I naively assumed that you might actually know what you were talking about - an understandable mistake, I think, because vsprintf.c is _a fucking mess_ and high stack usage would be believable. But the main part we're concerned with here, snprint() or prt_printf(), has no such stack usage problems. On v5.18, the frame size is under 64 bytes. On my branch, it's 72 bytes - higher because we do need to save arguments on the stack for the pretty-printer invocation, and there's no way around that without dropping to asm - although I'm allowing up to 8 arguments (besides the printbuf itself), which is probably excessive. So I'm not seeing what you're talking about. In the leaf functions, the individual pretty-printers/%p extensions, those are doing completely ridiculous things and I have fixed them all except symbol_string() on my branch, and I'll get to that one. Having a proper string library with useful helpers really makes things easier, it turns out. As for recursive %pf() invocations blowing the stack? I seriously fucking doubt it, once you're in a pretty-printer where you've already got a printbuf you can output to there's not much reason to be doing recursive calls to prt_printf() passing it yet another pretty printer - that's not where %pf() is convenient, what it makes convenient is using pretty printers when you're calling printk() directly. In a pretty printer fuction, if you want to do recursive pretty-printer calls you'd just call it directly! prt_printf(out, "%pf(%p)"), foo_to_text, foo) is silly when you can just call foo_to_text(out, foo). Now, I ask both of you please take your bureaucratic nitpicky nonsense and, kindly, pretty please with sugar on top - stuff it. I much prefer to work with people who don't waste my time, and who have actual _taste_.
