From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9D94B29CE6 for ; Fri, 21 Mar 2025 04:46:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742532374; cv=none; b=gBBdd++L3TokZ9eUufVplzE+HCI1CzTUGGT3JiVz7ieW1a5oQMD+Ns0vh9B83rkQsjPD/YSJpEajA+LZ1nPIZ2WEG9Ailmza1Qcr6e35SyTcc0+OoIbN+exUIneRiBtxRFF1FR0zOzs7vvyxqb4gmRarAVyukGz9brsfPUZeYQU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742532374; c=relaxed/simple; bh=yvL5kKnUqr+x35yQfVJfg8HpB2muzewzcEsOdC0WCkw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Bvoshdu/bVVzchEraLY4+AbZNNtXlX4u5I5Uk4Jt7rDgzltz2T1vUB1wrFdajwlgQRn3Hcmzp2XNSfgrbGLGA4UBeCjQDUa2hJJNkm8+UJo+XbljLwcYiCcCOmR8nz9XvYSpLoiJURS/XiioEGjFZJZEaHkWMq6mnQcvGrxuvpQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=ZYjfxA19; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="ZYjfxA19" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 23B45C4CEE8; Fri, 21 Mar 2025 04:46:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1742532374; bh=yvL5kKnUqr+x35yQfVJfg8HpB2muzewzcEsOdC0WCkw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ZYjfxA19JT9SuLKI2+te8ONjvra/EsWsp6z/gfcmo1+joqZKW++ZDM6OMaBrPrlj1 s26kc3XWSTNby/uXoZS5q1PHLsqT031BJLa2H8VjLU1PJp9cbXhCgTvJCyra5ijAGD JLV8cK8MWhaAhAc0MlYKBbcKPRw3NuwaXMn+/gDQ= Date: Thu, 20 Mar 2025 21:44:54 -0700 From: Greg Kroah-Hartman To: Hou Wenlong Cc: linux-kernel@vger.kernel.org, Arnd Bergmann Subject: Re: [PATCH] char: misc: Use __register_chrdev() to register the actual minor counts Message-ID: <2025032054-stylus-chemist-1cd4@gregkh> References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Fri, Mar 21, 2025 at 11:54:42AM +0800, Hou Wenlong wrote: > In commit ab760791c0cf ("char: misc: Increase the maximum number of > dynamic misc devices to 1048448"), the minor number of misc char device > is increased to MINORMASK + 1. However, it still uses register_chrdev(), > which defaults to registering the misc char device with only 256 minor > numbers. Therefore, when a misc device is given a minor number greater > than 255, the device file fails to open in kobj_lookup(). As a solution, > use __register_chrdev() to register the actual minor counts to > accommodate this increase. > > Signed-off-by: Hou Wenlong > --- > In our environment, the per-cpu coresight_tmc driver occupies too many > minor numbers, which ultimately allocates minor number 256 for our misc > device, resulting in a failure to open the device file in /dev. I'm not > sure if this is a bug or if userspace can only use fewer than 256 minor > numbers. Therefore, I didn't add a fix tag here. > --- > drivers/char/misc.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/char/misc.c b/drivers/char/misc.c > index f7dd455dd0dd..dda466f9181a 100644 > --- a/drivers/char/misc.c > +++ b/drivers/char/misc.c > @@ -315,7 +315,7 @@ static int __init misc_init(void) > goto fail_remove; > > err = -EIO; > - if (register_chrdev(MISC_MAJOR, "misc", &misc_fops)) > + if (__register_chrdev(MISC_MAJOR, 0, MINORMASK + 1, "misc", &misc_fops)) > goto fail_printk; > return 0; > > -- > 2.31.1 > I think this is the same change as this one: https://lore.kernel.org/r/20250317-misc-chrdev-v1-1-6cd05da11aef@igalia.com right? If so, can you provide a reviewed-by or tested-by on that one? I haven't picked it up yet, sorry. greg k-h