Paul E. McKenney
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Paul E. McKenney
paulmckrcu
Time flies! This is tomorrow, Tuesday July 7th at 8AM Pacific Time. Should be fun!!!
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Paul E. McKenney
paulmckrcu
@uecker You lost me on this one. The same pointer-zap solution as adopted by WG21? If so, I am reviewing N3226 (a working draft that led to TS 6010) to attempt to produce an initial proposal. I could present that here, but I suspect that Mastodon isn't the best communications medium for this sort of thing. So left to myself, I would post to the SC22WG14. But is there a better venue?
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Paul E. McKenney
paulmckrcu
@uecker I apologize, but I really cannot resist suggesting that providing a way of cleanly supporting ABA-tolerant concurrent algorithms based on TS 6010 is a necessary (though probably not sufficient) step towards convincing WG21 of the value of this TS. ;-)
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Paul E. McKenney
paulmckrcu
@uecker Here is hoping that in the case of C, starting with TS 6010 will make things easier and more clearly defined.
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Paul E. McKenney
paulmckrcu
@uecker If it makes you feel any better, I do understand that a different approach to lifetime-end pointer zap will be required for the C language. Presumably something based on ISO/IEC TS 6010.
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Paul E. McKenney
paulmckrcu
@uecker Define "clearly defined". ;-)
I would say "yes", but it is probably better to point you to this paper and let you decide: https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2025/p2434r4.html
I would expect that this would not satisfy you, but perhaps the good news is that I expect that things will be more clear in the context of ISO/IEC TS 6010. It would still be the case that a pointer exposed concurrently with an access would use that pointer, though it might be possible to provide at least some limits on this.
I would say "yes", but it is probably better to point you to this paper and let you decide: https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2025/p2434r4.html
I would expect that this would not satisfy you, but perhaps the good news is that I expect that things will be more clear in the context of ISO/IEC TS 6010. It would still be the case that a pointer exposed concurrently with an access would use that pointer, though it might be possible to provide at least some limits on this.
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Paul E. McKenney
paulmckrcu
@uecker If you are asking how this maps to the C-language ISO/IEC TS 6010, that is yet to be determined. I long ago resigned myself to different approaches for C++, C, and Rust.
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Paul E. McKenney
paulmckrcu
Some good progress on lifetime-end pointer zap and out-of-thin-air values in C++29! https://people.kernel.org/paulmck/c-pointer-zap-and-oota-progress
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Paul E. McKenney
paulmckrcu
@ljs @mairacanal Sort of like traffic. You should always drive politely, but most governments reserve the right to respond violently to people violating traffic laws in too dangerous a fashion.
Quick Quiz: In an open-source project, what comprises the government? ;-)
Quick Quiz: In an open-source project, what comprises the government? ;-)
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Paul E. McKenney
paulmckrcu
On July 7th, the inimitable Shuah Khan will be interviewing me on my life as a Linux-kernel developer and maintainer. And it is not just every day that this old man gets an invitation to reminisce! Kidding aside, it has been an exciting journey, and I hope to be able to share some of that excitement with you. ;-)
https://www.linuxfoundation.org/webinars/my-life-as-a-linux-kernel-developer-and-maintainer-with-paul-e.-mckenney?hsLang=en
https://www.linuxfoundation.org/webinars/my-life-as-a-linux-kernel-developer-and-maintainer-with-paul-e.-mckenney?hsLang=en
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Paul E. McKenney
paulmckrcu
@nixzhu @sundogplanets We just need heavy industry in orbit so that the potential and kinetic energy of those satellites can be recycled. ;-)
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Paul E. McKenney
paulmckrcu
@jwseigh I suspect that the Rust folks will eventually end up with something similar. But who knows?
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Paul E. McKenney
paulmckrcu
Bad things can happen if you leak pointers out of RCU read-side critical sections. What can you do about it?
https://people.kernel.org/paulmck/stupid-rcu-tricks-detecting-pointer-leaks
https://people.kernel.org/paulmck/stupid-rcu-tricks-detecting-pointer-leaks
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Paul E. McKenney
paulmckrcu
May the Fourth be with you!
And it is only fitting to celebrate Cinco de Mayo.
But beware...
For if you party too hearty, you may find yourself subject to the Revenge of the Sixth!
And it is only fitting to celebrate Cinco de Mayo.
But beware...
For if you party too hearty, you may find yourself subject to the Revenge of the Sixth!
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Paul E. McKenney
paulmckrcu
What would a C++ RCU API look like? https://people.kernel.org/paulmck/stupid-rcu-tricks-rcu-api-in-cpp26
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Paul E. McKenney
paulmckrcu
For those who have been asking for hardcopies of "Is Parallel Programming Hard, And, If So, What Can You Do About It?", I received my new hardcopy of the Second Edition. Enjoy!
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Paul E. McKenney
paulmckrcu
@jwseigh I completely agree with your "depends on the data structure"!
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Paul E. McKenney
paulmckrcu
@pkhuong Unless you object, I will add this to the blog. Something like "Paul Khuong reports that this technique was used in production for some time, until a more principled and sufficiently performant technique was put in its place."
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Paul E. McKenney
paulmckrcu
@pkhuong Understood, and this is why I said "Choose wisely" rather than something like "Never ever do it this way". In your case, I am glad that you guys found something that worked for you.
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