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Mon, 8 Nov 2021 15:35:59 +0100 (CET) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa1.perex.cz 4B03CF80107 Authentication-Results: alsa1.perex.cz; dkim=pass (1024-bit key) header.d=alien8.de header.i=@alien8.de header.b="Upd25Hzf" Received: from zn.tnic (p200300ec2f331100b486bab6e60d7aaf.dip0.t-ipconnect.de [IPv6:2003:ec:2f33:1100:b486:bab6:e60d:7aaf]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id 1A75E1EC01FC; Mon, 8 Nov 2021 15:35:56 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1636382156; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:in-reply-to:in-reply-to: references:references; bh=B6oOQ1q4gjLTOu5usgfET43xDRmf4tLazw1TZ6CRXFw=; b=Upd25HzfEqhrG5TAXmV4X7VLTXjG+2mbIZvAcNaA5XdFGwWxC22cjGdH367SqKuC2YI35V XePkT+plNO8Rcdx9qRLbflORPHDjzc4q/HfinrM2oVoUmKJ3f3FbXqZbeiIVI7zzNRafCc NDGlsVX5pxz7i7hCYlNzvvCrAxbHbAs= Date: Mon, 8 Nov 2021 15:35:50 +0100 From: Borislav Petkov To: Alan Stern , Geert Uytterhoeven Subject: Re: [PATCH v0 00/42] notifiers: Return an error when callback is already registered Message-ID: References: <20211108101157.15189-1-bp@alien8.de> <20211108101924.15759-1-bp@alien8.de> <20211108141703.GB1666297@rowland.harvard.edu> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: X-Mailman-Approved-At: Mon, 08 Nov 2021 16:29:18 +0100 Cc: alsa-devel@alsa-project.org, x86@kernel.org, linux-sh@vger.kernel.org, linux-iio@vger.kernel.org, linux-remoteproc@vger.kernel.org, linux-hyperv@vger.kernel.org, linux-mips@vger.kernel.org, netdev@vger.kernel.org, Ayush Sawal , sparclinux@vger.kernel.org, linux-clk@vger.kernel.org, linux-leds@vger.kernel.org, linux-s390@vger.kernel.org, linux-scsi@vger.kernel.org, Rohit Maheshwari , linux-staging@lists.linux.dev, bcm-kernel-feedback-list@broadcom.com, xen-devel@lists.xenproject.org, linux-xtensa@linux-xtensa.org, Arnd Bergmann , linux-pm@vger.kernel.org, intel-gfx@lists.freedesktop.org, Vinay Kumar Yadav , linux-um@lists.infradead.org, Steven Rostedt , rcu@vger.kernel.org, linux-fbdev@vger.kernel.org, linux-tegra@vger.kernel.org, openipmi-developer@lists.sourceforge.net, intel-gvt-dev@lists.freedesktop.org, linux-arm-kernel@lists.infradead.org, linux-edac@vger.kernel.org, linux-parisc@vger.kernel.org, Greg Kroah-Hartman , linux-usb@vger.kernel.org, LKML , linux-renesas-soc@vger.kernel.org, linux-crypto@vger.kernel.org, linux-alpha@vger.kernel.org, linuxppc-dev@lists.ozlabs.org X-BeenThere: alsa-devel@alsa-project.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: "Alsa-devel mailing list for ALSA developers - http://www.alsa-project.org" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: alsa-devel-bounces@alsa-project.org Sender: "Alsa-devel" On Mon, Nov 08, 2021 at 03:24:39PM +0100, Borislav Petkov wrote: > I guess I can add another indirection to notifier_chain_register() and > avoid touching all the call sites. IOW, something like this below. This way I won't have to touch all the callsites and the registration routines would still return a proper value instead of returning 0 unconditionally. --- diff --git a/kernel/notifier.c b/kernel/notifier.c index b8251dc0bc0f..04f08b2ef17f 100644 --- a/kernel/notifier.c +++ b/kernel/notifier.c @@ -19,14 +19,12 @@ BLOCKING_NOTIFIER_HEAD(reboot_notifier_list); * are layered on top of these, with appropriate locking added. */ -static int notifier_chain_register(struct notifier_block **nl, - struct notifier_block *n) +static int __notifier_chain_register(struct notifier_block **nl, + struct notifier_block *n) { while ((*nl) != NULL) { - if (unlikely((*nl) == n)) { - WARN(1, "double register detected"); - return 0; - } + if (unlikely((*nl) == n)) + return -EEXIST; if (n->priority > (*nl)->priority) break; nl = &((*nl)->next); @@ -36,6 +34,18 @@ static int notifier_chain_register(struct notifier_block **nl, return 0; } +static int notifier_chain_register(struct notifier_block **nl, + struct notifier_block *n) +{ + int ret = __notifier_chain_register(nl, n); + + if (ret == -EEXIST) + WARN(1, "double register of notifier callback %ps detected", + n->notifier_call); + + return ret; +} + static int notifier_chain_unregister(struct notifier_block **nl, struct notifier_block *n) { -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette