From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=91.218.175.67 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794317388; b=IawGarvbbk89U5emlrOWabkofJCkKN36uTdxupRffFtRfR5Eat5EzgCCNMoMNaeuQuQF GJVUkF26Var+mIq1+nSLuo0XmM91KJS0JJkNho+Qvwaaw6cdyNTym0jGVSSkP3H+Wo1pq /Zy6SbqyKN+k4f7WtwUUDFAAgR5WqNBJiV3nbK2N+0S4RN7p3iunCN/LgCuTnAV0cWplV xZjLVrfO8EfG5JPsG/J8M1A2W0CbGlvJtj6aJEJQ1rnPhzPWXS2Zr0qk85vr6IYNZxV8l ZsWDqLIRQUXLENEu7o1nomCFMNW0mODxlkhJDKEQUsf/uJ9ckVp41KVS41mCyNl6Rbg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794317388; 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=BDc1IvI6OsHXdrQ8x74AtWRkft+aXE3pPjEVY606+KI=; b=2IBvPSUhLkWHZlRiPJDlhlF/ln6F2Qkr7ynIn/ME1wWA2JheiuY4qNbO4NhNMAyP3jVz 8rsITPRV5fFCrh0t9QCrTXZc64JIHbKQrU3AV0QzfJAGTmODY9d/GquahnMga2P3kLehO 1G33ocX5YPlXGolWoRGcD14zKz5SElJByWn6D46TMHAsRVo8jtUGZZmHX53mFkQcykeQO x8ZKbrJ1C/Vm8H35vaLRmV5iE2wFCUVNJWN7jXYZFn92TDYmx9fbY539r8yTajmj2JMd2 Y49kqNS4XqRZ4Xf10bmc0H0ZPZMZsowPOj6gMQagJ7agMWw676OpKznoi2fNw5nencQ== 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=TuAh6bOa; arc=none smtp.remote-ip=91.218.175.67 Received: from mta0.migadu.com (out-67.mta0.migadu.com [91.218.175.67]) (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 7032D606A762 for ; Tue, 10 Nov 2026 13:29:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 7032D606A762 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=TuAh6bOa X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=t58bLFbopiLhye+XA8VecW5nbJtFNFWoJdVnDP5nc/A=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1794317385; v=1; x=1794922185; b=TuAh6bOaCEJ+qkh32W6hcLuO20vUvAF91Oks8v1acJWAjGdr2C4BnhO8Np4CiVaRofvfposs upwDnqSTXrBYcFYcPZqMuz63UQ4snMxiLv7deeLjiPHLPfWHyyouTzygsE7rpia5QQW9tq9fNHh MX/gp9GA19pV3zoLK1ZjpTZI= X-Envelope-To: linux-kernel@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id a77828bfa05a4d54; Tue, 10 Nov 2026 13:29:45 +0000 X-Mizu-Trace-ID: a77828bfa05a4d54 X-Migadu-Flow: FLOW_OUT From: Qiliang Yuan Date: Tue, 10 Nov 2026 08:29:34 -0500 Subject: [PATCH 2/2] scsi: target: alua: Drop the grace period wait from LUN detach 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-v1-2-127a46efdae9@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_remove_lun() detaches a LUN from its ALUA target port group once transport_clear_lun_ref() has drained its I/O, and target_detach_tg_pt_gp() then waits for an RCU grace period. Nothing that wait could protect is freed here: the group lives on until core_alua_free_tg_pt_gp(), which waits for a grace period of its own before freeing it, and the se_lun is freed with call_rcu(). Every LUN removed through configfs still pays a grace period for it. Remove the synchronize_rcu() call. Removing 256 LUNs from 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 5222 (5165-5244) 3551 (3436-3810) -32% 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 35d36cd36db6c..4e22f988bb83f 100644 --- a/drivers/target/target_core_alua.c +++ b/drivers/target/target_core_alua.c @@ -1858,7 +1858,6 @@ void target_detach_tg_pt_gp(struct se_lun *lun) rcu_assign_pointer(lun->lun_tg_pt_gp, NULL); } spin_unlock(&lun->lun_tg_pt_gp_lock); - synchronize_rcu(); } static void target_swap_tg_pt_gp(struct se_lun *lun, -- 2.43.0