From patchwork Mon Oct 11 17:40:41 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Simmons X-Patchwork-Id: 12550725 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 19B96C433F5 for ; Mon, 11 Oct 2021 17:41:20 +0000 (UTC) Received: from pdx1-mailman02.dreamhost.com (pdx1-mailman02.dreamhost.com [64.90.62.194]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id CA92960EB6 for ; Mon, 11 Oct 2021 17:41:19 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org CA92960EB6 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=lists.lustre.org Received: from pdx1-mailman02.dreamhost.com (localhost [IPv6:::1]) by pdx1-mailman02.dreamhost.com (Postfix) with ESMTP id 638E9380EB7; Mon, 11 Oct 2021 10:41:07 -0700 (PDT) Received: from smtp3.ccs.ornl.gov (smtp3.ccs.ornl.gov [160.91.203.39]) by pdx1-mailman02.dreamhost.com (Postfix) with ESMTP id CC65721FDCE for ; Mon, 11 Oct 2021 10:40:56 -0700 (PDT) Received: from star.ccs.ornl.gov (star.ccs.ornl.gov [160.91.202.134]) by smtp3.ccs.ornl.gov (Postfix) with ESMTP id BFE65465; Mon, 11 Oct 2021 13:40:51 -0400 (EDT) Received: by star.ccs.ornl.gov (Postfix, from userid 2004) id BE8D6D5A46; Mon, 11 Oct 2021 13:40:51 -0400 (EDT) From: James Simmons To: Andreas Dilger , Oleg Drokin , NeilBrown Date: Mon, 11 Oct 2021 13:40:41 -0400 Message-Id: <1633974049-26490-13-git-send-email-jsimmons@infradead.org> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1633974049-26490-1-git-send-email-jsimmons@infradead.org> References: <1633974049-26490-1-git-send-email-jsimmons@infradead.org> Subject: [lustre-devel] [PATCH 12/20] lustre: ptlrpc: use wait_woken() in ptlrpcd() X-BeenThere: lustre-devel@lists.lustre.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: "For discussing Lustre software development." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Lustre Development List MIME-Version: 1.0 Errors-To: lustre-devel-bounces@lists.lustre.org Sender: "lustre-devel" From: Mr NeilBrown Using wait_event() to wait for ptlrpcd_check() to succeed is problematic. ptlrpcd_check() is complex and can wait for other events. This nested waiting can behave differently to expectation and generates a warning do not call blocking ops when !TASK_RUNNING This happens because the task state is set to TASK_IDLE before ptlrpcd_check() is calls. A better approach (introduce for precisely this use-case) is to use wait_woken() and woken_wake_function(). When a wake_up is requested on the waitq, woken_wake_function() sets a flag to record the wakeup. wait_woken() will wait until this flag is set. This way, the task state doesn't need to be set until after ptlrpcd_check() has completed. WC-bug-id: https://jira.whamcloud.com/browse/LU-12362 Lustre-commit: 885b494632ca16d95 ("LU-12362 ptlrpc: use wait_woken() in ptlrpcd()") Signed-off-by: Mr NeilBrown Reviewed-on: https://review.whamcloud.com/45069 Reviewed-by: James Simmons Reviewed-by: Patrick Farrell Reviewed-by: xinliang Reviewed-by: Oleg Drokin Signed-off-by: James Simmons --- fs/lustre/ptlrpc/ptlrpcd.c | 23 ++++++++++++++++++----- 1 file changed, 18 insertions(+), 5 deletions(-) diff --git a/fs/lustre/ptlrpc/ptlrpcd.c b/fs/lustre/ptlrpc/ptlrpcd.c index ed3f0e1..9cd9d39 100644 --- a/fs/lustre/ptlrpc/ptlrpcd.c +++ b/fs/lustre/ptlrpc/ptlrpcd.c @@ -435,18 +435,31 @@ static int ptlrpcd(void *arg) * new_req_list and ptlrpcd_check() moves them into the set. */ do { + DEFINE_WAIT_FUNC(wait, woken_wake_function); time64_t timeout; timeout = ptlrpc_set_next_timeout(set); lu_context_enter(&env.le_ctx); lu_context_enter(env.le_ses); - /* If timeout==0, wait indefinitely */ - if (wait_event_idle_timeout( - set->set_waitq, - ptlrpcd_check(&env, pc), - timeout ? (timeout * HZ) : MAX_SCHEDULE_TIMEOUT) == 0) + + add_wait_queue(&set->set_waitq, &wait); + while (!ptlrpcd_check(&env, pc)) { + int ret; + + if (timeout == 0) + ret = wait_woken(&wait, TASK_IDLE, + MAX_SCHEDULE_TIMEOUT); + else + ret = wait_woken(&wait, TASK_IDLE, + HZ * timeout); + if (ret != 0) + continue; + /* Timed out */ ptlrpc_expired_set(set); + break; + } + remove_wait_queue(&set->set_waitq, &wait); lu_context_exit(&env.le_ctx); lu_context_exit(env.le_ses);