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Donenfeld" Cc: Al Viro , Theodore Ts'o , Christoph Hellwig , LKML References: <20220520094459.116240-1-Jason@zx2c4.com> <7e78d6a7-1cc3-2408-fe91-0329f5020e77@kernel.dk> <69bd18e6-d216-dfb3-201b-f6a285deb0e7@kernel.dk> From: Jens Axboe In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/20/22 10:39 AM, Jason A. Donenfeld wrote: > Hi Jens, > > On Fri, May 20, 2022 at 10:24:36AM -0600, Jens Axboe wrote: >> On 5/20/22 10:15 AM, Al Viro wrote: >>> IIRC, Linus' position at the time had been along the lines of >>> "splice is not so good ABI anyway, so let's do it and fix up >>> the places that do get real-world complaints once such appear". >>> So /dev/urandom is one such place... >> >> That's what Christoph said too. Honestly that's a very odd way to >> attempt to justify breakage like this, even if it is tempting to >> facilitate the set_fs() removal. But then be honest about it and say >> it like it is, rather than some hand wavy explanation that frankly >> doesn't make any sense. >> >> The referenced change doesn't change the splice ABI at all, hence the >> justification seems very random to me. It kept what we already have, >> except we randomly break some use cases. > > It looks like Al is right in the sense that Linus must certainly be > aware of the breakage. He fixed tty in 9bb48c82aced ("tty: implement > write_iter"). I don't think anyone is disputing that, but I also know that Linus wants these fixed up as they are discovered. And I agree with him on that, even if I disagree on the process to get there as it introduced frivolous breakage... > Anyway, it seems like the iter functions are the way forward, so this v4 > is queued up now (with a few minor cosmetic changes) and pushed to: > https://git.kernel.org/pub/scm/linux/kernel/git/crng/random.git/log/ > I'll send an early 5.19 pull for everything either tonight or Sunday. > And then next week I'll start on backports. (Though, 5.12 is a weird > kernel version; I assume this is some Meta kernel that has its own > backport team?) Thanks! > Meanwhile, hopefully Al can pick up the splice.c sendfile(2) chardev > patch for 5.19, so at least there'll be some silver lining to the > performance hit. Let's hope so. -- Jens Axboe