linux-kernel - Re: [POC 1/6] irq & spin_lock: Add counted interrupt disabling/enabling

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Message-ID: <87bjz95sc4.ffs@tglx>
Date: Thu, 24 Oct 2024 19:22:19 +0200
From: Thomas Gleixner <tglx@...utronix.de>
To: Peter Zijlstra <peterz@...radead.org>
Cc: Boqun Feng <boqun.feng@...il.com>, Dirk Behme <dirk.behme@...il.com>,
 Lyude Paul <lyude@...hat.com>, rust-for-linux@...r.kernel.org, Danilo
 Krummrich <dakr@...hat.com>, airlied@...hat.com, Ingo Molnar
 <mingo@...hat.com>, will@...nel.org, Waiman Long <longman@...hat.com>,
 linux-kernel@...r.kernel.org, Miguel Ojeda <ojeda@...nel.org>, Alex Gaynor
 <alex.gaynor@...il.com>, wedsonaf@...il.com, Gary Guo <gary@...yguo.net>,
 Björn Roy Baron <bjorn3_gh@...tonmail.com>, Benno Lossin
 <benno.lossin@...ton.me>, Andreas Hindborg <a.hindborg@...sung.com>,
 aliceryhl@...gle.com, Trevor Gross <tmgross@...ch.edu>
Subject: Re: [POC 1/6] irq & spin_lock: Add counted interrupt
 disabling/enabling

On Thu, Oct 24 2024 at 12:05, Peter Zijlstra wrote:
> On Wed, Oct 23, 2024 at 10:38:38PM +0200, Thomas Gleixner wrote:
>> But if we want to support insanity then we make preempt count 64 bit and
>> be done with it. But no, I don't think that encouraging insanity is a
>> good thing.
>
> The problem is that in most release builds the overflow will be silent
> and cause spurious weirdness that is a pain in the arse to debug :/
>
> That is my only concern -- making insane code crash hard is good, making
> it silently mostly work but cause random weirdness is not.

I wish we could come up with a lightweight check for that.

Thanks,

        tglx