From: Peter Zijlstra <peterz@infradead.org>
To: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Robin Murphy <robin.murphy@arm.com>,
Joerg Roedel <joro@8bytes.org>, Will Deacon <will@kernel.org>,
linux-kernel@vger.kernel.org, iommu@lists.linux.dev,
Randy Dunlap <rdunlap@infradead.org>,
"Paul E. McKenney" <paulmck@kernel.org>
Subject: Re: [PATCH] iommu: Convert unreachable() to BUG()
Date: Thu, 27 Mar 2025 13:37:18 +0100 [thread overview]
Message-ID: <20250327123718.GB31358@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <0c801ae017ec078cacd39f8f0898fc7780535f85.1743053325.git.jpoimboe@kernel.org>
On Wed, Mar 26, 2025 at 10:28:46PM -0700, Josh Poimboeuf wrote:
> Bare unreachable() should be avoided as it generates undefined behavior,
> e.g. falling through to the next function. Use BUG() instead so the
> error is defined.
Right; I did a pass like this a while ago and thought I'd removed all
unreachable() abuse.
Compilers see this as a clue to just stop code-gen. Very bad behaviour
if you ever actually get there. BUG() at the very least stops the kernel
dead, instead of continuing to run random code that comes after.
next prev parent reply other threads:[~2025-03-27 12:37 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-03-27 5:28 [PATCH] iommu: Convert unreachable() to BUG() Josh Poimboeuf
2025-03-27 12:37 ` Peter Zijlstra [this message]
2025-04-02 0:50 ` Josh Poimboeuf
2025-04-02 7:52 ` Peter Zijlstra
2025-03-27 13:00 ` Jason Gunthorpe
2025-03-27 14:58 ` Paul E. McKenney
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