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 388AC7C092; Mon, 8 Apr 2024 14:01:13 +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=1712584874; cv=none; b=tzCuZMkFmTrdRlZS7AS1IlxAJZVcjaOC6IWUd8FIlMcC2JkXxHTiqqqnwQs4zkx44CYGLrZNbsUNYz5exubD1jNgfwIIOdNDMBEImc403mWJgNmceE6LOk2YbiPawLBEaGekXDilMPw38/XZWwyU+kZRPe8c36UtXfay04rGVEI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712584874; c=relaxed/simple; bh=uid/OMQJ312PcQM4dt5mc1HmzNYdV+VOSr3UmNWQkwE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=WnbYKZ1PS2XkAru5LN58aafs4fueaJpmprArHJUkdzzdIKio/24C9DFLfF9qKlfBtnkiqLKGe/zTJ/hU0uwbR0hc5QQomloPAv6+UyrwVDn++mvzSI+d5xNbz5Aw85fyUW3/S9LQ8RWf2uddme7RYsp8Qf/iDQYkLeEx7C/nVwM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=H+FNtqqG; 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="H+FNtqqG" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 719F8C433C7; Mon, 8 Apr 2024 14:01:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1712584873; bh=uid/OMQJ312PcQM4dt5mc1HmzNYdV+VOSr3UmNWQkwE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=H+FNtqqGgQsBdUi+EgnsNVfWqohcjJJInEAhv8JhlWiiqBtlL1jGqnqhzlusDJ5Kf l/kA79f9OGL9SI49p5YeDuFiVBhqo26Q/gg2qLgEHqgccSUu3FHMt5CFVKUWt4UG8e /qC7oyk02FzXYAixuHycncHC4d+RQZTbr6wZ8WBY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, NeilBrown , Chuck Lever Subject: [PATCH 5.15 546/690] nfsd: Simplify code around svc_exit_thread() call in nfsd() Date: Mon, 8 Apr 2024 14:56:52 +0200 Message-ID: <20240408125419.428394000@linuxfoundation.org> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20240408125359.506372836@linuxfoundation.org> References: <20240408125359.506372836@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 5.15-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 --- fs/nfsd/nfssvc.c | 23 ----------------------- include/linux/sunrpc/svc.h | 13 ------------- 2 files changed, 36 deletions(-) diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c index 8063fab2c0279..8907dba22c3f2 100644 --- a/fs/nfsd/nfssvc.c +++ b/fs/nfsd/nfssvc.c @@ -979,31 +979,8 @@ nfsd(void *vrqstp) atomic_dec(&nfsdstats.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; } diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h index 53405c282209f..6e48c1c88f1bb 100644 --- a/include/linux/sunrpc/svc.h +++ b/include/linux/sunrpc/svc.h @@ -123,19 +123,6 @@ static inline void svc_put(struct svc_serv *serv) 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 -- 2.43.0