From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754118AbeDWCcx (ORCPT ); Sun, 22 Apr 2018 22:32:53 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:33846 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753977AbeDWCbX (ORCPT ); Sun, 22 Apr 2018 22:31:23 -0400 From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, fweisbec@gmail.com, oleg@redhat.com, joel.opensrc@gmail.com, "Paul E. McKenney" Subject: [PATCH tip/core/rcu 17/22] EXP: rcu: Abstract addition of debugging information to assertion Date: Sun, 22 Apr 2018 19:32:22 -0700 X-Mailer: git-send-email 2.5.2 In-Reply-To: <20180423023150.GA21533@linux.vnet.ibm.com> References: <20180423023150.GA21533@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 18042302-0044-0000-0000-0000040972DC X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00008903; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000257; SDB=6.01021888; UDB=6.00521536; IPR=6.00801123; MB=3.00020719; MTD=3.00000008; XFM=3.00000015; UTC=2018-04-23 02:31:20 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18042302-0045-0000-0000-0000083B7BD9 Message-Id: <1524450747-22778-17-git-send-email-paulmck@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-04-23_01:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=1 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1804230025 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Signed-off-by: Paul E. McKenney --- kernel/rcu/tree.c | 18 ++---------------- kernel/rcu/tree.h | 1 + kernel/rcu/tree_plugin.h | 29 +++++++++++++++++++++++++++++ 3 files changed, 32 insertions(+), 16 deletions(-) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 6ad2ac34558f..3bfd1519d378 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -2147,22 +2147,8 @@ static void rcu_gp_cleanup(struct rcu_state *rsp) */ rcu_for_each_node_breadth_first(rsp, rnp) { raw_spin_lock_irq_rcu_node(rnp); -#ifdef CONFIG_PREEMPT_RCU - if (WARN_ON_ONCE(rcu_preempt_blocked_readers_cgp(rnp))) { - int i; - struct task_struct *t; - - pr_info("%s: grp: %d-%d level: %d ->gp_tasks %p ->exp_tasks %p &->blkd_tasks: %p offset: %u\n", __func__, rnp->grplo, rnp->grphi, rnp->level, rnp->gp_tasks, rnp->exp_tasks, &rnp->blkd_tasks, (unsigned int)offsetof(typeof(*rnp), blkd_tasks)); - pr_cont("\t->blkd_tasks"); - i = 0; - list_for_each_entry(t, &rnp->blkd_tasks, rcu_node_entry) { - pr_cont(" %p", t); - if (++i >= 10) - break; - } - pr_cont("\n"); - } -#endif /* #ifdef CONFIG_PREEMPT_RCU */ + if (WARN_ON_ONCE(rcu_preempt_blocked_readers_cgp(rnp))) + dump_blkd_tasks(rnp, 10); WARN_ON_ONCE(rnp->qsmask); WRITE_ONCE(rnp->completed, rsp->gpnum); rdp = this_cpu_ptr(rsp->rda); diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h index 0b3a90ebe225..23ae7c00d3c5 100644 --- a/kernel/rcu/tree.h +++ b/kernel/rcu/tree.h @@ -428,6 +428,7 @@ static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp); static void rcu_preempt_check_callbacks(void); void call_rcu(struct rcu_head *head, rcu_callback_t func); static void __init __rcu_init_preempt(void); +static void dump_blkd_tasks(struct rcu_node *rnp, int ncheck); static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags); static void rcu_preempt_boost_start_gp(struct rcu_node *rnp); static void invoke_rcu_callbacks_kthread(void); diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index b999032e9466..a2ae6b49f900 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -841,6 +841,27 @@ void exit_rcu(void) __rcu_read_unlock(); } +/* + * Dump the blocked-tasks state, but limit the list dump to the + * specified number of elements. + */ +static void dump_blkd_tasks(struct rcu_node *rnp, int ncheck) +{ + int i; + struct list_head *lhp; + + lockdep_assert_held(&rnp->lock); + pr_info("%s: grp: %d-%d level: %d ->gp_tasks %p ->exp_tasks %p &->blkd_tasks: %p offset: %u\n", __func__, rnp->grplo, rnp->grphi, rnp->level, rnp->gp_tasks, rnp->exp_tasks, &rnp->blkd_tasks, (unsigned int)offsetof(typeof(*rnp), blkd_tasks)); + pr_cont("\t->blkd_tasks"); + i = 0; + list_for_each(lhp, &rnp->blkd_tasks) { + pr_cont(" %p", lhp); + if (++i >= 10) + break; + } + pr_cont("\n"); +} + #else /* #ifdef CONFIG_PREEMPT_RCU */ static struct rcu_state *const rcu_state_p = &rcu_sched_state; @@ -949,6 +970,14 @@ void exit_rcu(void) { } +/* + * Dump the guaranteed-empty blocked-tasks state. Trust but verify. + */ +static void dump_blkd_tasks(struct rcu_node *rnp, int ncheck) +{ + WARN_ON_ONCE(!list_empty(&rnp->blkd_tasks)); +} + #endif /* #else #ifdef CONFIG_PREEMPT_RCU */ #ifdef CONFIG_RCU_BOOST -- 2.5.2