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 0729A1C7B97; Tue, 27 Aug 2024 15:31:24 +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=1724772684; cv=none; b=KSB1bvAJy2sdQZ14qnHW5Kq6iFQZcQEXo+UTlPthrpOwjVborDngfGzyYbNj5NWLssCvnjhARSkYJy1YXigxkKKkFB8OTZR0o/CH+N2T9TbdPyAkmjGsIzz4CPU6jIOQI7wxok588Y3I5DTng5zbU51YJP5w6eXKougMRw81IRo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724772684; c=relaxed/simple; bh=Lq+KSAcRZ5WXEbmipjcTCPIr+/hY+fIN+EbCYNhERoI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=pv6s5/Jrq7ngBW2BHdQMiQq7QYfKEkbvyvW1AXla1Pi2ddyZJc0F7RU1Tz1K+W6xIfXTsNSvbWzvAPJ0twfzCUP+8dX2RtoSA5yMoNI/TDghfAEKdD6Wo7PdukgmHx4TfUK7i81qaduFUGQIeYlrwd9sVqh6WJSH4Awk3Hvh/hs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=TOnNoS7e; 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="TOnNoS7e" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 68A92C4DDF0; Tue, 27 Aug 2024 15:31:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1724772683; bh=Lq+KSAcRZ5WXEbmipjcTCPIr+/hY+fIN+EbCYNhERoI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=TOnNoS7eZXYAKIjb4qjquTLZ2POnpN1ftmTzGRZGK+DPv7K/COZCvsGinCnmr1I4K Z22OnlLXxxabAhwYbkiX1/h8J00CHG0gyfRt+9Pk6TjF8CKCc3T5VptM1hfQNXSzUu g1JAs48Nz4vjyuSkdBdCU169ikgW7rRUGoH9jUC8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, NeilBrown , Chuck Lever Subject: [PATCH 6.1 288/321] nfsd: Simplify code around svc_exit_thread() call in nfsd() Date: Tue, 27 Aug 2024 16:39:56 +0200 Message-ID: <20240827143849.211262411@linuxfoundation.org> X-Mailer: git-send-email 2.46.0 In-Reply-To: <20240827143838.192435816@linuxfoundation.org> References: <20240827143838.192435816@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: NeilBrown [ Upstream commit 18e4cf915543257eae2925671934937163f5639b ] Previously a thread could exit asynchronously (due to a signal) so some care was needed to hold nfsd_mutex over the last svc_put() call. Now a thread can only exit when svc_set_num_threads() is called, and this is always called under nfsd_mutex. So no care is needed. Not only is the mutex held when a thread exits now, but the svc refcount is elevated, so the svc_put() in svc_exit_thread() will never be a final put, so the mutex isn't even needed at this point in the code. Signed-off-by: NeilBrown Signed-off-by: Chuck Lever Signed-off-by: Greg Kroah-Hartman --- fs/nfsd/nfssvc.c | 23 ----------------------- include/linux/sunrpc/svc.h | 13 ------------- 2 files changed, 36 deletions(-) --- a/fs/nfsd/nfssvc.c +++ b/fs/nfsd/nfssvc.c @@ -983,31 +983,8 @@ nfsd(void *vrqstp) atomic_dec(&nfsd_th_cnt); out: - /* Take an extra ref so that the svc_put in svc_exit_thread() - * doesn't call svc_destroy() - */ - svc_get(nn->nfsd_serv); - /* Release the thread */ svc_exit_thread(rqstp); - - /* We need to drop a ref, but may not drop the last reference - * without holding nfsd_mutex, and we cannot wait for nfsd_mutex as that - * could deadlock with nfsd_shutdown_threads() waiting for us. - * So three options are: - * - drop a non-final reference, - * - get the mutex without waiting - * - sleep briefly andd try the above again - */ - while (!svc_put_not_last(nn->nfsd_serv)) { - if (mutex_trylock(&nfsd_mutex)) { - nfsd_put(net); - mutex_unlock(&nfsd_mutex); - break; - } - msleep(20); - } - return 0; } --- a/include/linux/sunrpc/svc.h +++ b/include/linux/sunrpc/svc.h @@ -123,19 +123,6 @@ static inline void svc_put(struct svc_se kref_put(&serv->sv_refcnt, svc_destroy); } -/** - * svc_put_not_last - decrement non-final reference count on SUNRPC serv - * @serv: the svc_serv to have count decremented - * - * Returns: %true is refcount was decremented. - * - * If the refcount is 1, it is not decremented and instead failure is reported. - */ -static inline bool svc_put_not_last(struct svc_serv *serv) -{ - return refcount_dec_not_one(&serv->sv_refcnt.refcount); -} - /* * Maximum payload size supported by a kernel RPC server. * This is use to determine the max number of pages nfsd is