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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@joelfernandes.org, "Paul E. McKenney" Subject: [PATCH tip/core/rcu 2/8] rcu: Rename rcu_check_callbacks() to rcu_sched_clock_irq() Date: Wed, 9 Jan 2019 13:41:36 -0800 X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190109214115.GA2835@linux.ibm.com> References: <20190109214115.GA2835@linux.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 19010921-0072-0000-0000-000003E73EA2 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00010375; HX=3.00000242; KW=3.00000007; PH=3.00000004; SC=3.00000274; SDB=6.01144149; UDB=6.00595711; IPR=6.00924412; MB=3.00025056; MTD=3.00000008; XFM=3.00000015; UTC=2019-01-09 21:41:49 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19010921-0073-0000-0000-00004ABF70CE Message-Id: <20190109214142.4428-2-paulmck@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-01-09_10:,, 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 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1901090172 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The name rcu_check_callbacks() arguably made sense back in the early 2000s when RCU was quite a bit simpler than it is today, but it has become quite misleading, especially with the advent of dyntick-idle and NO_HZ_FULL. The rcu_check_callbacks() function is RCU's hook into the scheduling-clock interrupt, and is now but one of many ways that callbacks get promoted to invocable state. This commit therefore changes the name to rcu_sched_clock_irq(), which is the same number of characters and clearly indicates this function's relation to the rest of the Linux kernel. In addition, for the sake of consistency, rcu_flavor_check_callbacks() is also renamed to rcu_flavor_sched_clock_irq(). While in the area, the header comments for both functions are reworked. Signed-off-by: Paul E. McKenney --- .../Tree-RCU-Memory-Ordering.html | 4 ++-- .../TreeRCU-callback-invocation.svg | 2 +- .../RCU/Design/Memory-Ordering/TreeRCU-gp.svg | 4 ++-- .../RCU/Design/Memory-Ordering/TreeRCU-qs.svg | 2 +- include/linux/rcupdate.h | 2 +- kernel/rcu/tiny.c | 2 +- kernel/rcu/tree.c | 18 +++++++------- kernel/rcu/tree.h | 2 +- kernel/rcu/tree_plugin.h | 24 ++++++++----------- kernel/time/timer.c | 2 +- 10 files changed, 29 insertions(+), 33 deletions(-) diff --git a/Documentation/RCU/Design/Memory-Ordering/Tree-RCU-Memory-Ordering.html b/Documentation/RCU/Design/Memory-Ordering/Tree-RCU-Memory-Ordering.html index e4d94fba6c89..a3acfd49255f 100644 --- a/Documentation/RCU/Design/Memory-Ordering/Tree-RCU-Memory-Ordering.html +++ b/Documentation/RCU/Design/Memory-Ordering/Tree-RCU-Memory-Ordering.html @@ -485,7 +485,7 @@ section that the grace period must wait on. noted by rcu_node_context_switch() on the left. On the other hand, if the CPU takes a scheduler-clock interrupt while executing in usermode, a quiescent state will be noted by -rcu_check_callbacks() on the right. +rcu_sched_clock_irq() on the right. Either way, the passage through a quiescent state will be noted in a per-CPU variable. @@ -651,7 +651,7 @@ to end. These callbacks are identified by rcu_advance_cbs(), which is usually invoked by __note_gp_changes(). As shown in the diagram below, this invocation can be triggered by -the scheduling-clock interrupt (rcu_check_callbacks() on +the scheduling-clock interrupt (rcu_sched_clock_irq() on the left) or by idle entry (rcu_cleanup_after_idle() on the right, but only for kernels build with CONFIG_RCU_FAST_NO_HZ=y). diff --git a/Documentation/RCU/Design/Memory-Ordering/TreeRCU-callback-invocation.svg b/Documentation/RCU/Design/Memory-Ordering/TreeRCU-callback-invocation.svg index 832408313d93..3fcf0c17cef2 100644 --- a/Documentation/RCU/Design/Memory-Ordering/TreeRCU-callback-invocation.svg +++ b/Documentation/RCU/Design/Memory-Ordering/TreeRCU-callback-invocation.svg @@ -349,7 +349,7 @@ font-weight="bold" font-size="192" id="text202-7-5" - style="font-size:192px;font-style:normal;font-weight:bold;text-anchor:start;fill:#000000;stroke-width:0.025in;font-family:Courier">rcu_check_callbacks() + style="font-size:192px;font-style:normal;font-weight:bold;text-anchor:start;fill:#000000;stroke-width:0.025in;font-family:Courier">rcu_sched_clock_irq() rcu_check_callbacks() + xml:space="preserve">rcu_sched_clock_irq() rcu_check_callbacks() + style="font-size:192px;font-style:normal;font-weight:bold;text-anchor:start;fill:#000000;stroke-width:0.025in;font-family:Courier">rcu_sched_clock_irq() rcu_check_callbacks() + xml:space="preserve">rcu_sched_clock_irq() rcu_read_unlock_special.b.need_qs = false; } } @@ -788,13 +788,13 @@ static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp) } /* - * Check for a quiescent state from the current CPU. When a task blocks, - * the task is recorded in the corresponding CPU's rcu_node structure, - * which is checked elsewhere. - * - * Caller must disable hard irqs. + * Check for a quiescent state from the current CPU, including voluntary + * context switches for Tasks RCU. When a task blocks, the task is + * recorded in the corresponding CPU's rcu_node structure, which is checked + * elsewhere, hence this function need only check for quiescent states + * related to the current CPU, not to those related to tasks. */ -static void rcu_flavor_check_callbacks(int user) +static void rcu_flavor_sched_clock_irq(int user) { struct task_struct *t = current; @@ -1088,14 +1088,10 @@ static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp) } /* - * Check to see if this CPU is in a non-context-switch quiescent state - * (user mode or idle loop for rcu, non-softirq execution for rcu_bh). - * Also schedule RCU core processing. - * - * This function must be called from hardirq context. It is normally - * invoked from the scheduling-clock interrupt. + * Check to see if this CPU is in a non-context-switch quiescent state, + * namely user mode and idle loop. */ -static void rcu_flavor_check_callbacks(int user) +static void rcu_flavor_sched_clock_irq(int user) { if (user || rcu_is_cpu_rrupt_from_idle()) { diff --git a/kernel/time/timer.c b/kernel/time/timer.c index 444156debfa0..6eb7cc4b6d52 100644 --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -1632,7 +1632,7 @@ void update_process_times(int user_tick) /* Note: this timer irq context must be accounted for as well. */ account_process_tick(p, user_tick); run_local_timers(); - rcu_check_callbacks(user_tick); + rcu_sched_clock_irq(user_tick); #ifdef CONFIG_IRQ_WORK if (in_irq()) irq_work_tick(); -- 2.17.1