Date: Wed, 13 Apr 2022 11:04:25 +0200 From: Christian Brauner <brauner@...nel.org> To: Arnd Bergmann <arnd@...nel.org> Cc: musl@...ts.openwall.com Subject: Re: Re: add loongarch64 port On Wed, Apr 13, 2022 at 10:26:06AM +0200, Arnd Bergmann wrote: > On Wed, Apr 13, 2022 at 9:26 AM Christian Brauner <brauner@...nel.org> wrote: > > On Sun, Apr 10, 2022 at 12:30:59PM +0200, Arnd Bergmann wrote: > > > On Sat, Apr 9, 2022 at 3:31 PM Rich Felker <dalias@...c.org> wrote: > > > > > > > > Actually, if there aren't yet archs lacking SYS_clone, this API > > > > regression may be a good argument not to drop SYS_clone on new archs > > > > yet until there's a way for new archs to get the same behavior > > > > (unspecified stack size). > > > > > > That is a good point, but it also appears that the behavior of > > > clone3() is unintentional > > > here, I'm fairly sure it was meant to be a drop-in replacement for clone() with > > > additional features. > > > > Mostly but not in all ways. We did decide it's ok to make API > > improvements that might break compatibility with legacy clone(). > > Ok > > > > > > > Not sure what the best fix for this is, as the check for size==0 was clearly > > > intentional, but seems to prevent this from working. A special flag to ignore > > > the size, or a magic size value like -1ull might work, but neither of them > > > is a great interface. > > > > Can someone explain the use-case in a bit more detail, please? > > > > If it is a legitimate use-case that callers need to be able to pass a > > stack and have no way of also passing a size then we should just remove > > the size == 0 check for all architectures that don't have a hard > > requirement on passing a size together with the stack pointer. > > > > Wdyt, Arnd? > > The normal rule is that we don't define obsolete system calls in new > architectures when an improved variant has been added, e.g. oldoldstat, > oldstat, stat, newstat and stat64 have all been replaced by statx over > the decades. I was expecting the same to be true for clone(), but if > clone3() is not meant as a replacement, we can keep both around. No, I agree with you on this and would like to only implement clone3() on new architectures. What I'm asking is whether removing the size == 0 check is enough to unblock the missing behavior and whether you'd be on board with removing the check?
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