From nobody Wed Dec 17 16:21:06 2025 Received: from mailgw02.mediatek.com (unknown [210.61.82.184]) (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 2C4A62BF01E for ; Wed, 27 Aug 2025 02:37:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=210.61.82.184 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756262261; cv=none; b=s+w/FSbd+zXHEwHBhbM4Dnma5r3ELuBMmrJSWlaLPTbYEqMNPECn33K8uzZK6YR9I8dl1dG3E3OMGDisa3+OetxkAjHjCW1ikSnEAsq/HNFLrttGm52jLf7ddw1xC5f8BxGdLKza0+btMgvs0VigkjemP68BErSh87C/TSjysus= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756262261; c=relaxed/simple; bh=IcfFXBC6vip/hTsmuCwRJQWKX01evLHIMzIfElDodN0=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=n0QDoflWUa9dZk7ZSUUWmST5y44fukf6LCozKJORfaEzwmD+AlN+6lmEpILjm71tfsD0E9XhfRjotXvZ2ooqvR8bcz79QYntNA9HexCMRqkBCTjkrPtIUB1Yf3yk5hhJ51+WCXoFHsSgmW4XWHmfJzggRu81+YiPpdyRVQYzbqI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=mediatek.com; spf=pass smtp.mailfrom=mediatek.com; dkim=pass (1024-bit key) header.d=mediatek.com header.i=@mediatek.com header.b=OwreRfaH; arc=none smtp.client-ip=210.61.82.184 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=mediatek.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=mediatek.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=mediatek.com header.i=@mediatek.com header.b="OwreRfaH" X-UUID: c8f9ae2682ee11f0b33aeb1e7f16c2b6-20250827 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=mediatek.com; s=dk; h=Content-Type:Content-Transfer-Encoding:MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:CC:To:From; bh=qqQOUmPhPDF+wRFVuZ8A8xxyMc7EM27KRGaAeuZra8I=; b=OwreRfaHxOeaRe24eDR6vrOwfwf21WwEEbIo4DQ12Otso1UubuYSuclmj95kqM5AGOAtkBZZdLWjm9U6V4UnoHfWxXmKV2FQTBXnAO+GB8HcMCnjSLO1jqnPRDIuRdZKvSaQIhbjJ+APVvRXuPFfPmKoDmBSuqMuRvartDXX/0I=; X-CID-P-RULE: Release_Ham X-CID-O-INFO: VERSION:1.3.3,REQID:2be08581-750d-4665-ac3f-2fd9cb8d849b,IP:0,UR L:0,TC:0,Content:22,EDM:0,RT:0,SF:0,FILE:0,BULK:0,RULE:Release_Ham,ACTION: release,TS:22 X-CID-META: VersionHash:f1326cf,CLOUDID:aae78f7a-966c-41bd-96b5-7d0b3c22e782,B ulkID:nil,BulkQuantity:0,Recheck:0,SF:81|82|102,TC:-5,Content:4|15|50,EDM: -3,IP:nil,URL:0,File:nil,RT:nil,Bulk:nil,QS:nil,BEC:nil,COL:0,OSI:0,OSA:0, AV:0,LES:1,SPR:NO,DKR:0,DKP:0,BRR:0,BRE:0,ARC:0 X-CID-BVR: 3,DMD|SSN|SDN X-CID-BAS: 3,DMD|SSN|SDN,0,_ X-CID-FACTOR: TF_CID_SPAM_SNR X-CID-RHF: D41D8CD98F00B204E9800998ECF8427E X-UUID: c8f9ae2682ee11f0b33aeb1e7f16c2b6-20250827 Received: from mtkmbs11n1.mediatek.inc [(172.21.101.185)] by mailgw02.mediatek.com (envelope-from ) (Generic MTA with TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384 256/256) with ESMTP id 1636638563; Wed, 27 Aug 2025 10:37:33 +0800 Received: from mtkmbs13n2.mediatek.inc (172.21.101.108) by MTKMBS09N1.mediatek.inc (172.21.101.35) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1258.39; Wed, 27 Aug 2025 10:37:32 +0800 Received: from mbjsdccf07.gcn.mediatek.inc (10.15.20.246) by mtkmbs13n2.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.2.1258.39 via Frontend Transport; Wed, 27 Aug 2025 10:37:31 +0800 From: To: Arnd Bergmann , Greg Kroah-Hartman , Matthias Brugger , AngeloGioacchino Del Regno CC: , , Xion Wang , , , Subject: [PATCH 1/1] misc: remove ineffective WARN_ON() check from misc_deregister() Date: Wed, 27 Aug 2025 10:41:00 +0800 Message-ID: <20250827024201.21407-2-xion.wang@mediatek.com> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20250827024201.21407-1-xion.wang@mediatek.com> References: <20250827024201.21407-1-xion.wang@mediatek.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-MTK: N Content-Type: text/plain; charset="utf-8" From: Xion Wang The WARN_ON(list_empty(&misc->list)) in misc_deregister() does not catch any practical error conditions: - For statically allocated miscdevice structures, the list pointers are zero-initialized, so list_empty() returns false, not true. - After list_del(), the pointers are set to LIST_POISON1 and LIST_POISON2, so repeated deregistration also fails to trigger the check. Signed-off-by: Xion Wang --- drivers/char/misc.c | 3 --- 1 file changed, 3 deletions(-) diff --git a/drivers/char/misc.c b/drivers/char/misc.c index 558302a64dd9..f46b00a76a59 100644 --- a/drivers/char/misc.c +++ b/drivers/char/misc.c @@ -275,9 +275,6 @@ EXPORT_SYMBOL(misc_register); =20 void misc_deregister(struct miscdevice *misc) { - if (WARN_ON(list_empty(&misc->list))) - return; - mutex_lock(&misc_mtx); list_del(&misc->list); device_destroy(&misc_class, MKDEV(MISC_MAJOR, misc->minor)); --=20 2.45.2