From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=91.218.175.63 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794317385; b=CcKXTNdUMytLkxjCSGn+sIaJgxwa+JqnxAAmhhqFcpxRTIGMxY34Lm52GjdBTC9vLdVY pRYup3vAsIUQxhsKascCZWgfpDfSUvHbPl9R/C8yrJ8HqwEJocdhXLe2HmeZ/xrcsJYGD WRH/+LRccsdXSiWi4LHxZKdyxQWjIW2VRuVaOlBJYNSQwt2gh73fAwafo8JDDVplXZqec rRGn6dJ4ICiL+YgpQbIKP8R0zqIMFNhHM6niXfaYiWuWX+qzWlMm6/SoUSDznJpl8Qc/X nWrw7wmJkYxXLjYeyQBLoAkj2U7m80vp/G7uq9RgjYz2g3JecIKUYoxcPnjsXJ153Ew== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794317385; h=DMARC-Filter:X-Envelope-To:DKIM-Signature:X-Envelope-To:Received: X-Mizu-Trace-ID:X-Migadu-Flow:From:Date:Subject:MIME-Version: Content-Type:Content-Transfer-Encoding:Message-Id:References: In-Reply-To:To:Cc:X-Mailer; bh=jgso6tJmEB2XfIL93/0JPnTAox6S4LW6+iOQSGCi6XY=; b=bY9KJB31UBxTTKKiwrDxjKKD1XGXHvTOuSjrnKMDu+VjBUbz8sQo8SqxkrS/xNUftDH5 WeGiLMFcDxkjKo3R+r/V9I1+suTgHlQIa4eXCUSjBRZnIBDcbtKj/2ijARsGQ5YhRJxBf KK+eEcoDo9lKmaT3EJ3sr+uw18twRWLpwljxt6EEwmeXS/vytatM+7hyEtAF5d4I50qJ5 pMCBr8/2pydZr89XL5gIgrgcAtSmJar+gLfc3Qy8EFA+PScPQb2VWpvZqr3W6+bbNS0B1 vZBiMaaxrOBzhPho7nR9ipiy/iCktp5z3F1l3cUwFDbZbDpe4VtwhmWwaYuU8qseIgQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b="orTvB/dy"; arc=none smtp.remote-ip=91.218.175.63 Received: from mta0.migadu.com (out-63.mta0.migadu.com [91.218.175.63]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 73DA8606A75B for ; Tue, 10 Nov 2026 13:29:44 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 73DA8606A75B Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=orTvB/dy X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=9cKpPKmEltljz99s+i6EK4S9sRHBgg9v/XDr1c1H/ps=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1794317382; v=1; x=1794922182; b=orTvB/dyxrHMpYCsImRyYMBXyZWB1OztYmlnPzJJQnIbCL4txFHl3e4BfprgWI/wlEKQ+xhP kHbfzzku2+u/M6xMwH/NH1tuetCKfzMekQBXwddof3JWsX9G6AJnvozmt933N6yYPmJqQN5kY8H OAd+ZxQKl4gY7H40DUzQ8rd8= X-Envelope-To: linux-kernel@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id 8423c878624c449f; Tue, 10 Nov 2026 13:29:42 +0000 X-Mizu-Trace-ID: 8423c878624c449f X-Migadu-Flow: FLOW_OUT From: Qiliang Yuan Date: Tue, 10 Nov 2026 08:29:33 -0500 Subject: [PATCH 1/2] scsi: target: alua: Don't wait for a grace period when attaching a LUN X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20261110-bug-target-alua-lun-gp-v1-1-127a46efdae9@linux.dev> References: <20261110-bug-target-alua-lun-gp-v1-0-127a46efdae9@linux.dev> In-Reply-To: <20261110-bug-target-alua-lun-gp-v1-0-127a46efdae9@linux.dev> To: "Martin K. Petersen" Cc: Mike Christie , linux-scsi@vger.kernel.org, target-devel@vger.kernel.org, linux-kernel@vger.kernel.org, Qiliang Yuan X-Mailer: b4 0.13.0 core_tpg_add_lun() attaches a new LUN to the default ALUA target port group before adding it to the device and TPG lists, and target_attach_tg_pt_gp() then waits for an RCU grace period. The wait protects nothing: lun->lun_tg_pt_gp goes from NULL to a live group, nothing is freed, and no reader can reach the LUN yet. It still costs a grace period for every LUN created through configfs, which dominates the time spent exporting many LUNs. Remove the synchronize_rcu() call. Group changes through core_alua_store_tg_pt_gp_info() keep their own grace period. Adding 256 LUNs to an iSCSI TPG through configfs, five rounds alternating with and without this patch, takes (median, min-max in parentheses): LUNs before (ms) after (ms) change 256 3144 (3104-3175) 1379 (1277-1393) -56% Signed-off-by: Qiliang Yuan --- drivers/target/target_core_alua.c | 1 - 1 file changed, 1 deletion(-) diff --git a/drivers/target/target_core_alua.c b/drivers/target/target_core_alua.c index 140154d93c430..35d36cd36db6c 100644 --- a/drivers/target/target_core_alua.c +++ b/drivers/target/target_core_alua.c @@ -1833,7 +1833,6 @@ void target_attach_tg_pt_gp(struct se_lun *lun, spin_lock(&lun->lun_tg_pt_gp_lock); __target_attach_tg_pt_gp(lun, tg_pt_gp); spin_unlock(&lun->lun_tg_pt_gp_lock); - synchronize_rcu(); } static void __target_detach_tg_pt_gp(struct se_lun *lun, -- 2.43.0