linux-kernel - Re: [RFC PATCH 1/4] hazptr: Add initial implementation of hazard pointers

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Message-ID: <e2733938-06fa-46c3-8839-4349fe50d46f@efficios.com>
Date: Wed, 25 Sep 2024 15:20:59 +0200
From: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To: Boqun Feng <boqun.feng@...il.com>
Cc: Jonas Oberhauser <jonas.oberhauser@...weicloud.com>,
 linux-kernel@...r.kernel.org, rcu@...r.kernel.org, linux-mm@...ck.org,
 lkmm@...ts.linux.dev, "Paul E. McKenney" <paulmck@...nel.org>,
 Frederic Weisbecker <frederic@...nel.org>,
 Neeraj Upadhyay <neeraj.upadhyay@...nel.org>,
 Joel Fernandes <joel@...lfernandes.org>,
 Josh Triplett <josh@...htriplett.org>, Uladzislau Rezki <urezki@...il.com>,
 Steven Rostedt <rostedt@...dmis.org>, Lai Jiangshan
 <jiangshanlai@...il.com>, Zqiang <qiang.zhang1211@...il.com>,
 Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
 Will Deacon <will@...nel.org>, Waiman Long <longman@...hat.com>,
 Mark Rutland <mark.rutland@....com>, Thomas Gleixner <tglx@...utronix.de>,
 Kent Overstreet <kent.overstreet@...il.com>,
 Linus Torvalds <torvalds@...ux-foundation.org>,
 Vlastimil Babka <vbabka@...e.cz>, maged.michael@...il.com,
 Neeraj Upadhyay <neeraj.upadhyay@....com>
Subject: Re: [RFC PATCH 1/4] hazptr: Add initial implementation of hazard
 pointers

On 2024-09-25 15:10, Mathieu Desnoyers wrote:
[...]

Cleaner without goto in the user code:

#include <stdio.h>
#include <stdbool.h>

static inline
bool same_ptr(void *a, void *b)
{
     asm goto (
         "cmpq %[a], %[b]\n\t"
         "jne %l[ne]\n\t"
         : : [a] "r" (a), [b] "r" (b)
         : : ne);
     return true;
ne:
     return false;
}

int x;

int v[2];

int main(void)
{
     if (same_ptr(v, v + 1))
         x = 1;
     printf("%d\n", x);
     return 0;
}

-- 
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com