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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 Subject: [PATCH tip/core/rcu 0/19] RCU flavor-consolidation changes for v4.20/v5.0 Reply-To: paulmck@linux.vnet.ibm.com MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-GCONF: 00 x-cbid: 18082922-0068-0000-0000-00000331B7A7 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=6.00860723; MB=3.00023001; MTD=3.00000008; XFM=3.00000015; UTC=2018-08-29 22:20:26 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18082922-0069-0000-0000-0000458F0DCD Message-Id: <20180829222021.GA29944@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 Hello! This series contains the RCU flavor consolidation, along with some initial cleanup work enabled by that consolidation (and some that became apparent while cleaning up): 1. Refactor rcu_{nmi,irq}_{enter,exit}(), saving a branch on the idle entry/exit hotpaths, courtesy of Byungchul Park, 2. Defer reporting RCU-preempt quiescent states when disabled. This is the key commit that consolidates the RCU-bh and RCU-sched flavors into RCU, however, the RCU-bh and RCU-sched flavors still exist independently as well at this point. 3. Test extended "rcu" read-side critical sections. This commit causes rcutorture to test RCU's new-found ability to act as the combination of RCU, RCU-bh, and RCU-sched. 4. Allow processing deferred QSes for exiting RCU-preempt readers. This is a optimization. 5. Remove now-unused ->b.exp_need_qs field from the rcu_special union. 6. Add warning to detect half-interrupts. Test the claim that the Linux kernel no longer does half-interrupts. 7. Apply RCU-bh QSes to RCU-sched and RCU-preempt when safe, that is, make the consolidated RCU inherit RCU-bh's denial-of-service avoidance mechanism. 8. Report expedited grace periods at context-switch time. This is an optimization enabled by the RCU flavor consolidation. 9. Define RCU-bh update API in terms of RCU. This commit gets rid of the RCU-bh update mechanism. 10. Update comments and help text to account for the removal of the RCU-bh update mechanism. 11. Drop "wake" parameter from rcu_report_exp_rdp(). 12. Fix typo in rcu_get_gp_kthreads_prio() header comment. 13. Define RCU-sched API in terms of RCU for Tree RCU PREEMPT builds. Although this commit gets rid of the RCU-sched update mechanism from PREEMPT builds, it of course remains as the sole RCU flavor for !PREEMPT && !SMP builds. 14. Express Tiny RCU updates in terms of RCU rather than RCU-sched. This will enable additional cleanups and code savings. 15. Remove RCU_STATE_INITIALIZER() in favor of just using an open-coded initializer for the sole remaining rcu_state structure. 16. Eliminate rcu_state structure's ->call field, as it is now always just call_rcu(). 17. Remove rcu_state structure's ->rda field, as there is now only one set of per-CPU rcu_data structures. Thanx, Paul ------------------------------------------------------------------------ Documentation/RCU/Design/Requirements/Requirements.html | 50 - include/linux/rcupdate.h | 48 - include/linux/rcupdate_wait.h | 6 include/linux/rcutiny.h | 61 + include/linux/rcutree.h | 31 include/linux/sched.h | 6 kernel/rcu/Kconfig | 10 kernel/rcu/rcutorture.c | 1 kernel/rcu/tiny.c | 163 +-- kernel/rcu/tree.c | 655 +++++----------- kernel/rcu/tree.h | 44 - kernel/rcu/tree_exp.h | 256 +++--- kernel/rcu/tree_plugin.h | 523 ++++++------ kernel/rcu/update.c | 2 kernel/softirq.c | 3 15 files changed, 836 insertions(+), 1023 deletions(-)