From: Peter Zijlstra <peterz@infradead.org>
To: Borislav Petkov <bp@alien8.de>
Cc: X86 ML <x86@kernel.org>, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH] notifier: Return non-null when callback already registered
Date: Fri, 21 May 2021 13:11:42 +0200 [thread overview]
Message-ID: <YKeVbsLnAdpVUwAa@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20210520202033.23851-1-bp@alien8.de>
On Thu, May 20, 2021 at 10:20:33PM +0200, Borislav Petkov wrote:
> From: Borislav Petkov <bp@suse.de>
>
> The notifier registration routine doesn't return a proper error value
> when a callback has already been registered, leading people to track
> whether that regisration has happened at the call site:
>
> https://lore.kernel.org/amd-gfx/20210512013058.6827-1-mukul.joshi@amd.com/
>
> Which is unnecessary.
>
> Return a non-null to signal that case so that callers can act
> accordingly.
>
> Signed-off-by: Borislav Petkov <bp@suse.de>
> ---
> kernel/notifier.c | 10 +++++-----
> 1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/kernel/notifier.c b/kernel/notifier.c
> index 1b019cbca594..ff7a3198c5fc 100644
> --- a/kernel/notifier.c
> +++ b/kernel/notifier.c
> @@ -25,7 +25,7 @@ static int notifier_chain_register(struct notifier_block **nl,
> while ((*nl) != NULL) {
> if (unlikely((*nl) == n)) {
> WARN(1, "double register detected");
That should give a big clue^
> - return 0;
> + return 1;
How about -EBUSY here?
next prev parent reply other threads:[~2021-05-21 11:14 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-20 20:20 [RFC PATCH] notifier: Return non-null when callback already registered Borislav Petkov
2021-05-21 11:11 ` Peter Zijlstra [this message]
2021-05-21 14:06 ` Borislav Petkov
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