----- Ursprüngliche Mail ----- > Von: "Dark" <d...@volatile.bz> > An: "Richard Weinberger" <richard.weinber...@gmail.com>, "linux-kernel" > <linux-kernel@vger.kernel.org> > CC: "richard" <rich...@nod.at>, "anton ivanov" > <anton.iva...@cambridgegreys.com>, "linux-um" > <linux...@lists.infradead.org> > Gesendet: Donnerstag, 29. August 2019 16:36:28 > Betreff: Re: [PATCH] um: Rewrite host RNG driver.
> On Thu, 29 Aug 2019 15:26:24 +0200, Richard Weinberger > <richard.weinber...@gmail.com> wrote: >> So, you removed -EAGAIN handling, made everything synchronous, >> and changed the interface.t >> I'm not sure if this really a much better option. > > I should have been more clear here that I'm using the interfaces > provided by `drivers/char/hw_random/core.c` for consistency with the > other hardware RNG drivers and to avoid reimplementing stuff that's > already there. I got this, and this is a good thing! > It might be a bit hard to see in the diff, but I pass the file > descriptor to `os_set_fd_async()` to prevent it from blocking. Well, it does not block but passing -EAGAIN directly back is not nice. Or does the hw_random framework handle this? > For the -EAGAIN handling, I'm passing it onto the caller. Since you > mentioned it, It would be better to handle it in the driver itself > so I'll update the patch to address that. > >> Rewriting the driver in a modern manner is a good thing, but throwing the >> old one way with a little hand weaving just because of a unspecified issue >> is a little harsh. >> Can you at lest provide more infos what problem you're facing with the >> old driver? > > Most of it boiled down to it silently breaking if /dev/random on the > host were to block for any reason, and there was the userspace tool > requirement to properly make use of it. With that said, the interface > was also inconsistent with the other hardware RNG drivers which would > require a rewrite to address anyway. Maybe our -EAGAIN handling is buggy. That said I'm all for changing the driver to use the right framework but please make sure that we don't drop useful stuff like -EAGAIN handling. Thanks, //richard
