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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 08/14] rcu: Trace end of grace period before end of grace period Date: Sun, 11 Nov 2018 11:28:58 -0800 X-Mailer: git-send-email 2.17.1 In-Reply-To: <20181111192839.GA32144@linux.ibm.com> References: <20181111192839.GA32144@linux.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 18111119-0052-0000-0000-0000035421B2 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00010028; HX=3.00000242; KW=3.00000007; PH=3.00000004; SC=3.00000270; SDB=6.01116014; UDB=6.00578730; IPR=6.00896114; MB=3.00024114; MTD=3.00000008; XFM=3.00000015; UTC=2018-11-11 19:29:10 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18111119-0053-0000-0000-00005EBB1CAD Message-Id: <20181111192904.3199-8-paulmck@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-11-11_13:,, 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-1811110185 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Currently, rcu_gp_cleanup() traces the end of the old grace period after the old grace period has officially ended. This might make intuitive sense, but it also makes for confusing event-trace output because the "end" trace displays not the old but instead the new grace-period number. This commit therefore traces the end of an old grace period just before that grace period officially ends. Reported-by: Aravinda Prasad Signed-off-by: Paul E. McKenney --- kernel/rcu/tree.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 429a46fb087a..61bae41b1afe 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -2035,9 +2035,9 @@ static void rcu_gp_cleanup(void) rnp = rcu_get_root(); raw_spin_lock_irq_rcu_node(rnp); /* GP before ->gp_seq update. */ - /* Declare grace period done. */ - rcu_seq_end(&rcu_state.gp_seq); + /* Declare grace period done, trace first to use old GP number. */ trace_rcu_grace_period(rcu_state.name, rcu_state.gp_seq, TPS("end")); + rcu_seq_end(&rcu_state.gp_seq); rcu_state.gp_state = RCU_GP_IDLE; /* Check for GP requests since above loop. */ rdp = this_cpu_ptr(&rcu_data); -- 2.17.1