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McKenney" To: rcu@vger.kernel.org Cc: linux-kernel@vger.kernel.org, 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@joelfernandes.org, "Paul E. McKenney" Subject: [PATCH tip/core/rcu 04/11] rcu: Inline RCU task stall-warning helper functions Date: Tue, 26 Mar 2019 16:22:18 -0700 X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190326232208.GA20384@linux.ibm.com> References: <20190326232208.GA20384@linux.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 19032623-0052-0000-0000-000003A187E7 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00010820; HX=3.00000242; KW=3.00000007; PH=3.00000004; SC=3.00000282; SDB=6.01180136; UDB=6.00617574; IPR=6.00960851; MB=3.00026169; MTD=3.00000008; XFM=3.00000015; UTC=2019-03-26 23:22:30 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19032623-0053-0000-0000-00006048DC36 Message-Id: <20190326232225.21332-4-paulmck@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-03-26_15:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=13 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=844 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1903260157 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The rcu_print_detail_task_stall(), rcu_print_task_stall_begin(), and rcu_print_task_stall_end() functions were defined to allow long-gone Kconfig options to provide an abbreviated RCU CPU stall warning printout. This commit saves a few lines of code by inlining them into their sole callers. While in the area, a useless call of rcu_print_detail_task_stall_rnp() on the root rcu_node structure was eliminated. If there is only one rcu_node structure, its tasks get printed twice, but if there are more, the root rcu_node structure is guaranteed to have an empty list of blocked tasks, hence the uselessness. (Long ago, root rcu_node structures with non-empty ->blkd_tasks lists could happen, but no longer.) Signed-off-by: Paul E. McKenney --- kernel/rcu/tree.h | 1 - kernel/rcu/tree_stall.h | 36 +++++++----------------------------- 2 files changed, 7 insertions(+), 30 deletions(-) diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h index 3c4e26fff806..c6df9a13dd06 100644 --- a/kernel/rcu/tree.h +++ b/kernel/rcu/tree.h @@ -445,7 +445,6 @@ static void rcu_dynticks_task_enter(void); static void rcu_dynticks_task_exit(void); /* Forward declarations for tree_stall.h */ -static void rcu_print_detail_task_stall(void); static int rcu_print_task_stall(struct rcu_node *rnp); static void record_gp_stall_check_time(void); static void check_cpu_stall(struct rcu_data *rdp); diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h index e0e73f493363..b476786b8ef7 100644 --- a/kernel/rcu/tree_stall.h +++ b/kernel/rcu/tree_stall.h @@ -94,30 +94,6 @@ static void rcu_print_detail_task_stall_rnp(struct rcu_node *rnp) raw_spin_unlock_irqrestore_rcu_node(rnp, flags); } -/* - * Dump detailed information for all tasks blocking the current RCU - * grace period. - */ -static void rcu_print_detail_task_stall(void) -{ - struct rcu_node *rnp = rcu_get_root(); - - rcu_print_detail_task_stall_rnp(rnp); - rcu_for_each_leaf_node(rnp) - rcu_print_detail_task_stall_rnp(rnp); -} - -static void rcu_print_task_stall_begin(struct rcu_node *rnp) -{ - pr_err("\tTasks blocked on level-%d rcu_node (CPUs %d-%d):", - rnp->level, rnp->grplo, rnp->grphi); -} - -static void rcu_print_task_stall_end(void) -{ - pr_cont("\n"); -} - /* * Scan the current list of tasks blocked within RCU read-side critical * sections, printing out the tid of each. @@ -129,14 +105,15 @@ static int rcu_print_task_stall(struct rcu_node *rnp) if (!rcu_preempt_blocked_readers_cgp(rnp)) return 0; - rcu_print_task_stall_begin(rnp); + pr_err("\tTasks blocked on level-%d rcu_node (CPUs %d-%d):", + rnp->level, rnp->grplo, rnp->grphi); t = list_entry(rnp->gp_tasks->prev, struct task_struct, rcu_node_entry); list_for_each_entry_continue(t, &rnp->blkd_tasks, rcu_node_entry) { pr_cont(" P%d", t->pid); ndetected++; } - rcu_print_task_stall_end(); + pr_cont("\n"); return ndetected; } @@ -146,7 +123,7 @@ static int rcu_print_task_stall(struct rcu_node *rnp) * Because preemptible RCU does not exist, we never have to check for * tasks blocked within RCU read-side critical sections. */ -static void rcu_print_detail_task_stall(void) +static void rcu_print_detail_task_stall_rnp(struct rcu_node *rnp) { } @@ -253,7 +230,7 @@ static void print_other_cpu_stall(unsigned long gp_seq) unsigned long gpa; unsigned long j; int ndetected = 0; - struct rcu_node *rnp = rcu_get_root(); + struct rcu_node *rnp; long totqlen = 0; /* Kick and suppress, if so configured. */ @@ -291,7 +268,8 @@ static void print_other_cpu_stall(unsigned long gp_seq) rcu_dump_cpu_stacks(); /* Complain about tasks blocking the grace period. */ - rcu_print_detail_task_stall(); + rcu_for_each_leaf_node(rnp) + rcu_print_detail_task_stall_rnp(rnp); } else { if (rcu_seq_current(&rcu_state.gp_seq) != gp_seq) { pr_err("INFO: Stall ended before state dump start\n"); -- 2.17.1