From: Jonas Oberhauser <jonas.oberhauser@huaweicloud.com>
To: Linus Torvalds <torvalds@linux-foundation.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Boqun Feng <boqun.feng@gmail.com>,
linux-kernel@vger.kernel.org, rcu@vger.kernel.org,
linux-mm@kvack.org, lkmm@lists.linux.dev,
"Paul E. McKenney" <paulmck@kernel.org>,
Frederic Weisbecker <frederic@kernel.org>,
Neeraj Upadhyay <neeraj.upadhyay@kernel.org>,
Joel Fernandes <joel@joelfernandes.org>,
Josh Triplett <josh@joshtriplett.org>,
"Uladzislau Rezki (Sony)" <urezki@gmail.com>,
rostedt <rostedt@goodmis.org>,
Lai Jiangshan <jiangshanlai@gmail.com>,
Zqiang <qiang.zhang1211@gmail.com>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>, Will Deacon <will@kernel.org>,
Waiman Long <longman@redhat.com>,
Mark Rutland <mark.rutland@arm.com>,
Thomas Gleixner <tglx@linutronix.de>,
Kent Overstreet <kent.overstreet@gmail.com>,
Vlastimil Babka <vbabka@suse.cz>,
maged.michael@gmail.com,
Neeraj Upadhyay <neeraj.upadhyay@amd.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: Re: [RFC PATCH 1/4] hazptr: Add initial implementation of hazard pointers
Date: Fri, 27 Sep 2024 21:12:09 +0200 [thread overview]
Message-ID: <1b04e35c-8994-48d9-907a-966bb4dfabaf@huaweicloud.com> (raw)
In-Reply-To: <CAHk-=wi_hz8Whs2ogRUQEfMBk=OkZ3usmvJkzb5YyEKwqEJBmQ@mail.gmail.com>
Am 9/27/2024 um 8:13 PM schrieb Linus Torvalds:
> Because even hiding the value one from the compiler will mean that it
> can't use the comparison to decide that the originals are equal, even
> if one of them is unhidden.
>
> No?
>
> Linus
I think it depends on which one you hide.
If you do
z = b;
hide(z);
if (a==z) { *b; }
then it will be fine, because it knows a==z but nothing about the
relation of b with a or z.
But for
z = a;
hide(z);
if (z==b) { *b; }
then it would still know that b == z, and could replace *b with *z
(which really is *a).
Best wishes,
jonas
next prev parent reply other threads:[~2024-09-27 19:12 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20240917143402.930114-1-boqun.feng@gmail.com>
[not found] ` <20240917143402.930114-2-boqun.feng@gmail.com>
[not found] ` <CA757E86-2AE4-4077-A07A-679E3BFDBC34@gmail.com>
2024-09-19 6:56 ` [RFC PATCH 1/4] hazptr: Add initial implementation of hazard pointers Boqun Feng
2024-09-19 18:07 ` Jonas Oberhauser
[not found] ` <CAJhGHyD8MzUssfuKSGnu1arnayNOyBnUA03vYB0WWwbE3WzoZg@mail.gmail.com>
2024-09-19 7:10 ` Boqun Feng
2024-09-19 12:33 ` Alan Huang
2024-09-19 13:57 ` Alan Huang
2024-09-19 18:58 ` Boqun Feng
2024-09-19 19:53 ` Alan Huang
2024-09-19 16:10 ` Alan Huang
[not found] ` <CAG48ez0VN8oZcqhdzkWQgNv6bwUN=MUu5EacLg5iPvMQL+R-Qg@mail.gmail.com>
2024-09-19 20:30 ` Jonas Oberhauser
2024-09-20 7:43 ` Jonas Oberhauser
[not found] ` <55975a55-302f-4c45-bfcc-192a8a1242e9@huaweicloud.com>
[not found] ` <ZvPfmAp_2mDkI3ss@boqun-archlinux>
[not found] ` <f5aeeeda-c725-422a-9481-4795bd3ade0f@huaweicloud.com>
2024-09-25 10:45 ` Boqun Feng
2024-09-25 11:59 ` Mathieu Desnoyers
2024-09-25 12:16 ` Boqun Feng
2024-09-25 12:47 ` Mathieu Desnoyers
2024-09-25 13:10 ` Mathieu Desnoyers
2024-09-25 13:20 ` Mathieu Desnoyers
2024-09-26 6:16 ` Mathieu Desnoyers
2024-09-26 15:53 ` Jonas Oberhauser
2024-09-26 16:12 ` Linus Torvalds
2024-09-26 16:40 ` Jonas Oberhauser
2024-09-26 16:54 ` Linus Torvalds
2024-09-27 0:01 ` Boqun Feng
2024-09-27 1:30 ` Mathieu Desnoyers
2024-09-27 1:37 ` Boqun Feng
2024-09-27 4:28 ` Boqun Feng
2024-09-27 10:59 ` Mathieu Desnoyers
2024-09-27 14:43 ` Mathieu Desnoyers
2024-09-27 15:22 ` Mathieu Desnoyers
2024-09-27 16:06 ` Alan Huang
2024-09-27 16:44 ` Linus Torvalds
2024-09-27 17:15 ` Mathieu Desnoyers
2024-09-27 17:23 ` Linus Torvalds
2024-09-27 17:51 ` Mathieu Desnoyers
2024-09-27 18:13 ` Linus Torvalds
2024-09-27 19:12 ` Jonas Oberhauser [this message]
2024-09-27 19:28 ` Linus Torvalds
2024-09-27 20:24 ` Linus Torvalds
2024-09-27 20:02 ` Mathieu Desnoyers
2024-09-27 1:20 ` Mathieu Desnoyers
2024-09-27 4:38 ` Boqun Feng
2024-09-27 19:23 ` Jonas Oberhauser
2024-09-27 20:10 ` Mathieu Desnoyers
2024-09-27 22:18 ` Jonas Oberhauser
2024-09-28 22:10 ` Alan Huang
2024-09-28 23:12 ` Alan Huang
2024-09-25 12:19 ` Jonas Oberhauser
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