From patchwork Thu Jan 9 19:07:42 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Paul E. McKenney" X-Patchwork-Id: 13933158 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 0231619C556 for ; Thu, 9 Jan 2025 19:07:43 +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=1736449664; cv=none; b=SaiEYXyD6NItKUDM/uKq90qXtEHfWD8Egnqb3wDjafgZW6w8LAobpejgvHax4YafudUId5VhSRI9QxCZT6Gtj2GZunUd+uDBLztE7Mqxzgq+P3uScz8ZMRTSWXsgBrRVyZefmltTNaO8VYTMTcNw2L5aQy8j8MIkEJ0+BTL0vxk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736449664; c=relaxed/simple; bh=DPkQ40FBUAaj9IHEH0Qec+XhXevOidtvsQHxrPGjdJg=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition; b=udVte7Lds+E/I6k9WoRnN8WFms1bG7zmlGlFYNs6sq28jPxHXRy2Hb5pTrILN3Thsj6K+DWKyu3ASmuxRLuGEEGShLSOmzwtZyr/serJ8p2Du2vRtcnjWLHV8n+cTyrpT2IoaGCw4omo6QuGFAciUteAPYQKYyeaAqMlBLBAaaw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=uOEXCfZz; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="uOEXCfZz" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 699B8C4CED2; Thu, 9 Jan 2025 19:07:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1736449663; bh=DPkQ40FBUAaj9IHEH0Qec+XhXevOidtvsQHxrPGjdJg=; h=Date:From:To:Cc:Subject:Reply-To:From; b=uOEXCfZzVKezzlC80jmDU+zt8jKuPsmh8gU56nS7XvMvwduFwww0989GGpOpKfhcD 8Ny/8qTgq/L4jiTQPsj2OB7WTWRBy8KZfPwOlvbI0rR4LXwXmpyaPSlzUTlrNk8Kse 4UTauw+BwRAcR56c5vlVqMSxTvwGlba/6jA2syn99Z+mr9d6h210/8zJFu3rm7JuTU OojE+LxxDCUAQNEu+4gVCmXruOP/h5HrlzZXG5w232yBXRIQZOCKNgt4vkMhWM+5ci fpL2R40mZZcIAtNfpaw+pM5tRxpivtYJkWRrYPoxwdOA4J6YSBFyqsbIpR3DZKn+Zc xxc4J9s1feaGQ== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id D18CFCE0B6D; Thu, 9 Jan 2025 11:07:42 -0800 (PST) Date: Thu, 9 Jan 2025 11:07:42 -0800 From: "Paul E. McKenney" To: rcu@vger.kernel.org Cc: frederic@kernel.org, boqun.feng@gmail.com, urezki@gmail.com, neeraj.iitr10@gmail.com, joel@joelfernandes.org Subject: [PATCH RFC] rcu/nocb: Print segment lengths in show_rcu_nocb_gp_state() Message-ID: Reply-To: paulmck@kernel.org Precedence: bulk X-Mailing-List: rcu@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Disposition: inline Analysis of an rcutorture callback-based forward-progress test failure was hampered by the lack of ->cblist segment lengths. This commit therefore adds this information, so that what would have been ".W85620.N." (there are some callbacks waiting for grace period sequence number 85620 and some number more that have not yet been assigned to a grace period) now prints as ".W2(85620).N6." (there are 2 callbacks waiting for grace period 85620 and 6 not yet assigned to a grace period). Note that "D" (done), "N" (next and not yet assigned to a grace period, and "B" (bypass, also not yet assigned to a grace period) have just the number of callbacks without the parenthesized grace-period sequence number. In contrast, "W" (waiting for the current grace period) and "R" (ready to wait for the next grace period to start) both have parenthesized grace-period sequence numbers. Signed-off-by: Paul E. McKenney diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c index 295789004d071..b7d5564104a5b 100644 --- a/kernel/rcu/rcutorture.c +++ b/kernel/rcu/rcutorture.c @@ -3047,6 +3047,7 @@ static void rcu_torture_fwd_prog_cr(struct rcu_fwd *rfp) n_launders_cb_snap = READ_ONCE(rfp->n_launders_cb); cver = READ_ONCE(rcu_torture_current_version) - cver; gps = rcutorture_seq_diff(cur_ops->get_gp_seq(), gps); + rcu_fwd_progress_check(rfp->rcu_fwd_id); pr_alert("%s: Waiting for CBs: %pS() %d\n", __func__, cur_ops->cb_barrier, rfp->rcu_fwd_id); cur_ops->cb_barrier(); /* Wait for callbacks to be invoked. */ (void)rcu_torture_fwd_prog_cbfree(rfp); diff --git a/kernel/rcu/tree_nocb.h b/kernel/rcu/tree_nocb.h index a03fc19abde73..4a954ecf1c36e 100644 --- a/kernel/rcu/tree_nocb.h +++ b/kernel/rcu/tree_nocb.h @@ -1551,8 +1551,11 @@ static void show_rcu_nocb_gp_state(struct rcu_data *rdp) /* Dump out nocb kthread state for the specified rcu_data structure. */ static void show_rcu_nocb_state(struct rcu_data *rdp) { - char bufw[20]; - char bufr[20]; + char bufd[22]; + char bufw[45]; + char bufr[45]; + char bufn[22]; + char bufb[22]; struct rcu_data *nocb_next_rdp; struct rcu_segcblist *rsclp = &rdp->cblist; bool waslocked; @@ -1566,9 +1569,13 @@ static void show_rcu_nocb_state(struct rcu_data *rdp) typeof(*rdp), nocb_entry_rdp); - sprintf(bufw, "%ld", rsclp->gp_seq[RCU_WAIT_TAIL]); - sprintf(bufr, "%ld", rsclp->gp_seq[RCU_NEXT_READY_TAIL]); - pr_info(" CB %d^%d->%d %c%c%c%c%c F%ld L%ld C%d %c%c%s%c%s%c%c q%ld %c CPU %d%s\n", + sprintf(bufd, "%ld", rsclp->seglen[RCU_DONE_TAIL]); + sprintf(bufw, "%ld(%ld)", rsclp->seglen[RCU_WAIT_TAIL], rsclp->gp_seq[RCU_WAIT_TAIL]); + sprintf(bufr, "%ld(%ld)", rsclp->seglen[RCU_NEXT_READY_TAIL], + rsclp->gp_seq[RCU_NEXT_READY_TAIL]); + sprintf(bufn, "%ld", rsclp->seglen[RCU_NEXT_TAIL]); + sprintf(bufb, "%ld", rcu_cblist_n_cbs(&rdp->nocb_bypass)); + pr_info(" CB %d^%d->%d %c%c%c%c%c F%ld L%ld C%d %c%s%c%s%c%s%c%s%c%s q%ld %c CPU %d%s\n", rdp->cpu, rdp->nocb_gp_rdp->cpu, nocb_next_rdp ? nocb_next_rdp->cpu : -1, "kK"[!!rdp->nocb_cb_kthread], @@ -1580,12 +1587,15 @@ static void show_rcu_nocb_state(struct rcu_data *rdp) jiffies - rdp->nocb_nobypass_last, rdp->nocb_nobypass_count, ".D"[rcu_segcblist_ready_cbs(rsclp)], + rcu_segcblist_segempty(rsclp, RCU_DONE_TAIL) ? "" : bufd, ".W"[!rcu_segcblist_segempty(rsclp, RCU_WAIT_TAIL)], rcu_segcblist_segempty(rsclp, RCU_WAIT_TAIL) ? "" : bufw, ".R"[!rcu_segcblist_segempty(rsclp, RCU_NEXT_READY_TAIL)], rcu_segcblist_segempty(rsclp, RCU_NEXT_READY_TAIL) ? "" : bufr, ".N"[!rcu_segcblist_segempty(rsclp, RCU_NEXT_TAIL)], + rcu_segcblist_segempty(rsclp, RCU_NEXT_TAIL) ? "" : bufn, ".B"[!!rcu_cblist_n_cbs(&rdp->nocb_bypass)], + !rcu_cblist_n_cbs(&rdp->nocb_bypass) ? "" : bufb, rcu_segcblist_n_cbs(&rdp->cblist), rdp->nocb_cb_kthread ? task_state_to_char(rdp->nocb_cb_kthread) : '.', rdp->nocb_cb_kthread ? (int)task_cpu(rdp->nocb_cb_kthread) : -1,