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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 04/19] rcu: Allow processing deferred QSes for exiting RCU-preempt readers Date: Wed, 29 Aug 2018 15:20:32 -0700 X-Mailer: git-send-email 2.17.1 In-Reply-To: <20180829222021.GA29944@linux.vnet.ibm.com> References: <20180829222021.GA29944@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 18082922-0060-0000-0000-000002A6628D X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00009636; HX=3.00000242; KW=3.00000007; PH=3.00000004; SC=3.00000266; SDB=6.01080738; UDB=6.00557494; IPR=6.00860724; MB=3.00023001; MTD=3.00000008; XFM=3.00000015; UTC=2018-08-29 22:20:53 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18082922-0061-0000-0000-00004655AED3 Message-Id: <20180829222047.319-4-paulmck@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-08-29_06:,, 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=8.0.1-1807170000 definitions=main-1808290217 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If an RCU-preempt read-side critical section is exiting, that is, ->rcu_read_lock_nesting is negative, then it is a good time to look at the possibility of reporting deferred quiescent states. This commit therefore updates the checks in rcu_preempt_need_deferred_qs() to allow exiting critical sections to report deferred quiescent states. Signed-off-by: Paul E. McKenney --- kernel/rcu/tree_plugin.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 542791361908..24c209676d20 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -602,7 +602,7 @@ static bool rcu_preempt_need_deferred_qs(struct task_struct *t) { return (this_cpu_ptr(&rcu_preempt_data)->deferred_qs || READ_ONCE(t->rcu_read_unlock_special.s)) && - !t->rcu_read_lock_nesting; + t->rcu_read_lock_nesting <= 0; } /* -- 2.17.1