Re: [PATCH] rcu: Refactor rcu_{nmi,irq}_{enter,exit}()

From: Paul E. McKenney
Date: Fri Jun 22 2018 - 09:37:12 EST

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In reply to: kbuild test robot: "Re: [PATCH] rcu: Refactor rcu_{nmi,irq}_{enter,exit}()"
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On Fri, Jun 22, 2018 at 04:34:48PM +0800, kbuild test robot wrote:
> Hi Byungchul,
>
> Thank you for the patch! Perhaps something to improve:
>
> [auto build test WARNING on rcu/rcu/next]
> [also build test WARNING on v4.18-rc1 next-20180622]
> [if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
>
> url: https://github.com/0day-ci/linux/commits/Byungchul-Park/rcu-Refactor-rcu_-nmi-irq-_-enter-exit/20180622-141334
> base: https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git rcu/next
> reproduce: make htmldocs
>
> All warnings (new ones prefixed by >>):
>
> WARNING: convert(1) not found, for SVG to PDF conversion install ImageMagick (https://www.imagemagick.org)
> >> kernel/rcu/tree.c:778: warning: Function parameter or member 'irq' not described in 'rcu_nmi_exit_common'
> >> kernel/rcu/tree.c:938: warning: Function parameter or member 'irq' not described in 'rcu_nmi_enter_common'

It is complaining about the docbook function-header comment. It wants
the "irq" parameter described, something like this:

* @irq: Is this call from rcu_irq_enter?

And similar for rcu_nmi_exit_common().

Thanx, Paul

> include/net/cfg80211.h:4216: warning: Function parameter or member 'wext.ibss' not described in 'wireless_dev'
> include/net/cfg80211.h:4216: warning: Function parameter or member 'wext.connect' not described in 'wireless_dev'
> include/net/cfg80211.h:4216: warning: Function parameter or member 'wext.keys' not described in 'wireless_dev'
> include/net/cfg80211.h:4216: warning: Function parameter or member 'wext.ie' not described in 'wireless_dev'
> include/net/cfg80211.h:4216: warning: Function parameter or member 'wext.ie_len' not described in 'wireless_dev'
> include/net/cfg80211.h:4216: warning: Function parameter or member 'wext.bssid' not described in 'wireless_dev'
> include/net/cfg80211.h:4216: warning: Function parameter or member 'wext.ssid' not described in 'wireless_dev'
> include/net/cfg80211.h:4216: warning: Function parameter or member 'wext.default_key' not described in 'wireless_dev'
> include/net/cfg80211.h:4216: warning: Function parameter or member 'wext.default_mgmt_key' not described in 'wireless_dev'
> include/net/cfg80211.h:4216: warning: Function parameter or member 'wext.prev_bssid_valid' not described in 'wireless_dev'
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2282: warning: Function parameter or member 'radiotap_timestamp.units_pos' not described in 'ieee80211_hw'
> include/net/mac80211.h:2282: warning: Function parameter or member 'radiotap_timestamp.accuracy' not described in 'ieee80211_hw'
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:955: warning: Function parameter or member 'control.rates' not described in 'ieee80211_tx_info'
> include/net/mac80211.h:955: warning: Function parameter or member 'control.rts_cts_rate_idx' not described in 'ieee80211_tx_info'
> include/net/mac80211.h:955: warning: Function parameter or member 'control.use_rts' not described in 'ieee80211_tx_info'
> include/net/mac80211.h:955: warning: Function parameter or member 'control.use_cts_prot' not described in 'ieee80211_tx_info'
> include/net/mac80211.h:955: warning: Function parameter or member 'control.short_preamble' not described in 'ieee80211_tx_info'
> include/net/mac80211.h:955: warning: Function parameter or member 'control.skip_table' not described in 'ieee80211_tx_info'
> include/net/mac80211.h:955: warning: Function parameter or member 'control.jiffies' not described in 'ieee80211_tx_info'
> include/net/mac80211.h:955: warning: Function parameter or member 'control.vif' not described in 'ieee80211_tx_info'
> include/net/mac80211.h:955: warning: Function parameter or member 'control.hw_key' not described in 'ieee80211_tx_info'
> include/net/mac80211.h:955: warning: Function parameter or member 'control.flags' not described in 'ieee80211_tx_info'
> include/net/mac80211.h:955: warning: Function parameter or member 'control.enqueue_time' not described in 'ieee80211_tx_info'
> include/net/mac80211.h:955: warning: Function parameter or member 'ack' not described in 'ieee80211_tx_info'
> include/net/mac80211.h:955: warning: Function parameter or member 'ack.cookie' not described in 'ieee80211_tx_info'
> include/net/mac80211.h:955: warning: Function parameter or member 'status.rates' not described in 'ieee80211_tx_info'
> include/net/mac80211.h:955: warning: Function parameter or member 'status.ack_signal' not described in 'ieee80211_tx_info'
> include/net/mac80211.h:955: warning: Function parameter or member 'status.ampdu_ack_len' not described in 'ieee80211_tx_info'
> include/net/mac80211.h:955: warning: Function parameter or member 'status.ampdu_len' not described in 'ieee80211_tx_info'
> include/net/mac80211.h:955: warning: Function parameter or member 'status.antenna' not described in 'ieee80211_tx_info'
> include/net/mac80211.h:955: warning: Function parameter or member 'status.tx_time' not described in 'ieee80211_tx_info'
> include/net/mac80211.h:955: warning: Function parameter or member 'status.is_valid_ack_signal' not described in 'ieee80211_tx_info'
> include/net/mac80211.h:955: warning: Function parameter or member 'status.status_driver_data' not described in 'ieee80211_tx_info'
> include/net/mac80211.h:955: warning: Function parameter or member 'driver_rates' not described in 'ieee80211_tx_info'
> include/net/mac80211.h:955: warning: Function parameter or member 'pad' not described in 'ieee80211_tx_info'
> include/net/mac80211.h:955: warning: Function parameter or member 'rate_driver_data' not described in 'ieee80211_tx_info'
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
> include/net/mac80211.h:2083: warning: bad line: >
>
> vim +778 kernel/rcu/tree.c
>
> 19dd1591f kernel/rcutree.c Frederic Weisbecker 2012-06-04 765
> 19dd1591f kernel/rcutree.c Frederic Weisbecker 2012-06-04 766 /**
> 1e8a49734 kernel/rcu/tree.c Byungchul Park 2018-06-22 767 * rcu_nmi_exit_common - inform RCU of exit from NMI context
> fd581a91a kernel/rcu/tree.c Paul E. McKenney 2017-10-02 768 *
> fd581a91a kernel/rcu/tree.c Paul E. McKenney 2017-10-02 769 * If we are returning from the outermost NMI handler that interrupted an
> fd581a91a kernel/rcu/tree.c Paul E. McKenney 2017-10-02 770 * RCU-idle period, update rdtp->dynticks and rdtp->dynticks_nmi_nesting
> fd581a91a kernel/rcu/tree.c Paul E. McKenney 2017-10-02 771 * to let the RCU grace-period handling know that the CPU is back to
> fd581a91a kernel/rcu/tree.c Paul E. McKenney 2017-10-02 772 * being RCU-idle.
> fd581a91a kernel/rcu/tree.c Paul E. McKenney 2017-10-02 773 *
> 1e8a49734 kernel/rcu/tree.c Byungchul Park 2018-06-22 774 * If you add or remove a call to rcu_nmi_exit_common(), be sure to test
> fd581a91a kernel/rcu/tree.c Paul E. McKenney 2017-10-02 775 * with CONFIG_RCU_EQS_DEBUG=y.
> fd581a91a kernel/rcu/tree.c Paul E. McKenney 2017-10-02 776 */
> 1e8a49734 kernel/rcu/tree.c Byungchul Park 2018-06-22 777 static __always_inline void rcu_nmi_exit_common(bool irq)
> fd581a91a kernel/rcu/tree.c Paul E. McKenney 2017-10-02 @778 {
> fd581a91a kernel/rcu/tree.c Paul E. McKenney 2017-10-02 779 struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
> fd581a91a kernel/rcu/tree.c Paul E. McKenney 2017-10-02 780
> fd581a91a kernel/rcu/tree.c Paul E. McKenney 2017-10-02 781 /*
> fd581a91a kernel/rcu/tree.c Paul E. McKenney 2017-10-02 782 * Check for ->dynticks_nmi_nesting underflow and bad ->dynticks.
> fd581a91a kernel/rcu/tree.c Paul E. McKenney 2017-10-02 783 * (We are exiting an NMI handler, so RCU better be paying attention
> fd581a91a kernel/rcu/tree.c Paul E. McKenney 2017-10-02 784 * to us!)
> fd581a91a kernel/rcu/tree.c Paul E. McKenney 2017-10-02 785 */
> fd581a91a kernel/rcu/tree.c Paul E. McKenney 2017-10-02 786 WARN_ON_ONCE(rdtp->dynticks_nmi_nesting <= 0);
> fd581a91a kernel/rcu/tree.c Paul E. McKenney 2017-10-02 787 WARN_ON_ONCE(rcu_dynticks_curr_cpu_in_eqs());
> fd581a91a kernel/rcu/tree.c Paul E. McKenney 2017-10-02 788
> fd581a91a kernel/rcu/tree.c Paul E. McKenney 2017-10-02 789 /*
> fd581a91a kernel/rcu/tree.c Paul E. McKenney 2017-10-02 790 * If the nesting level is not 1, the CPU wasn't RCU-idle, so
> fd581a91a kernel/rcu/tree.c Paul E. McKenney 2017-10-02 791 * leave it in non-RCU-idle state.
> fd581a91a kernel/rcu/tree.c Paul E. McKenney 2017-10-02 792 */
> fd581a91a kernel/rcu/tree.c Paul E. McKenney 2017-10-02 793 if (rdtp->dynticks_nmi_nesting != 1) {
> dec98900e kernel/rcu/tree.c Paul E. McKenney 2017-10-04 794 trace_rcu_dyntick(TPS("--="), rdtp->dynticks_nmi_nesting, rdtp->dynticks_nmi_nesting - 2, rdtp->dynticks);
> fd581a91a kernel/rcu/tree.c Paul E. McKenney 2017-10-02 795 WRITE_ONCE(rdtp->dynticks_nmi_nesting, /* No store tearing. */
> fd581a91a kernel/rcu/tree.c Paul E. McKenney 2017-10-02 796 rdtp->dynticks_nmi_nesting - 2);
> fd581a91a kernel/rcu/tree.c Paul E. McKenney 2017-10-02 797 return;
> fd581a91a kernel/rcu/tree.c Paul E. McKenney 2017-10-02 798 }
> fd581a91a kernel/rcu/tree.c Paul E. McKenney 2017-10-02 799
> fd581a91a kernel/rcu/tree.c Paul E. McKenney 2017-10-02 800 /* This NMI interrupted an RCU-idle CPU, restore RCU-idleness. */
> dec98900e kernel/rcu/tree.c Paul E. McKenney 2017-10-04 801 trace_rcu_dyntick(TPS("Startirq"), rdtp->dynticks_nmi_nesting, 0, rdtp->dynticks);
> fd581a91a kernel/rcu/tree.c Paul E. McKenney 2017-10-02 802 WRITE_ONCE(rdtp->dynticks_nmi_nesting, 0); /* Avoid store tearing. */
> 1e8a49734 kernel/rcu/tree.c Byungchul Park 2018-06-22 803
> 1e8a49734 kernel/rcu/tree.c Byungchul Park 2018-06-22 804 if (irq)
> 1e8a49734 kernel/rcu/tree.c Byungchul Park 2018-06-22 805 rcu_prepare_for_idle();
> 1e8a49734 kernel/rcu/tree.c Byungchul Park 2018-06-22 806
> fd581a91a kernel/rcu/tree.c Paul E. McKenney 2017-10-02 807 rcu_dynticks_eqs_enter();
> 1e8a49734 kernel/rcu/tree.c Byungchul Park 2018-06-22 808
> 1e8a49734 kernel/rcu/tree.c Byungchul Park 2018-06-22 809 if (irq)
> 1e8a49734 kernel/rcu/tree.c Byungchul Park 2018-06-22 810 rcu_dynticks_task_enter();
> 1e8a49734 kernel/rcu/tree.c Byungchul Park 2018-06-22 811 }
> 1e8a49734 kernel/rcu/tree.c Byungchul Park 2018-06-22 812
> 1e8a49734 kernel/rcu/tree.c Byungchul Park 2018-06-22 813 /**
> 1e8a49734 kernel/rcu/tree.c Byungchul Park 2018-06-22 814 * rcu_nmi_exit - inform RCU of exit from NMI context
> 1e8a49734 kernel/rcu/tree.c Byungchul Park 2018-06-22 815 */
> 1e8a49734 kernel/rcu/tree.c Byungchul Park 2018-06-22 816 void rcu_nmi_exit(void)
> 1e8a49734 kernel/rcu/tree.c Byungchul Park 2018-06-22 817 {
> 1e8a49734 kernel/rcu/tree.c Byungchul Park 2018-06-22 818 rcu_nmi_exit_common(false);
> fd581a91a kernel/rcu/tree.c Paul E. McKenney 2017-10-02 819 }
> fd581a91a kernel/rcu/tree.c Paul E. McKenney 2017-10-02 820
> fd581a91a kernel/rcu/tree.c Paul E. McKenney 2017-10-02 821 /**
> 9b2e4f188 kernel/rcutree.c Paul E. McKenney 2011-09-30 822 * rcu_irq_exit - inform RCU that current CPU is exiting irq towards idle
> 64db4cfff kernel/rcutree.c Paul E. McKenney 2008-12-18 823 *
> 9b2e4f188 kernel/rcutree.c Paul E. McKenney 2011-09-30 824 * Exit from an interrupt handler, which might possibly result in entering
> 9b2e4f188 kernel/rcutree.c Paul E. McKenney 2011-09-30 825 * idle mode, in other words, leaving the mode in which read-side critical
> 7c9906ca5 kernel/rcu/tree.c Paul E. McKenney 2015-10-31 826 * sections can occur. The caller must have disabled interrupts.
> 9b2e4f188 kernel/rcutree.c Paul E. McKenney 2011-09-30 827 *
> 9b2e4f188 kernel/rcutree.c Paul E. McKenney 2011-09-30 828 * This code assumes that the idle loop never does anything that might
> 9b2e4f188 kernel/rcutree.c Paul E. McKenney 2011-09-30 829 * result in unbalanced calls to irq_enter() and irq_exit(). If your
> 58721f5da kernel/rcu/tree.c Paul E. McKenney 2017-10-03 830 * architecture's idle loop violates this assumption, RCU will give you what
> 58721f5da kernel/rcu/tree.c Paul E. McKenney 2017-10-03 831 * you deserve, good and hard. But very infrequently and irreproducibly.
> 9b2e4f188 kernel/rcutree.c Paul E. McKenney 2011-09-30 832 *
> 9b2e4f188 kernel/rcutree.c Paul E. McKenney 2011-09-30 833 * Use things like work queues to work around this limitation.
> 9b2e4f188 kernel/rcutree.c Paul E. McKenney 2011-09-30 834 *
> 9b2e4f188 kernel/rcutree.c Paul E. McKenney 2011-09-30 835 * You have been warned.
> c0da313e0 kernel/rcu/tree.c Paul E. McKenney 2017-09-22 836 *
> c0da313e0 kernel/rcu/tree.c Paul E. McKenney 2017-09-22 837 * If you add or remove a call to rcu_irq_exit(), be sure to test with
> c0da313e0 kernel/rcu/tree.c Paul E. McKenney 2017-09-22 838 * CONFIG_RCU_EQS_DEBUG=y.
> 64db4cfff kernel/rcutree.c Paul E. McKenney 2008-12-18 839 */
> 9b2e4f188 kernel/rcutree.c Paul E. McKenney 2011-09-30 840 void rcu_irq_exit(void)
> 64db4cfff kernel/rcutree.c Paul E. McKenney 2008-12-18 841 {
> b04db8e19 kernel/rcu/tree.c Frederic Weisbecker 2017-11-06 842 lockdep_assert_irqs_disabled();
> 1e8a49734 kernel/rcu/tree.c Byungchul Park 2018-06-22 843 rcu_nmi_exit_common(true);
> 7c9906ca5 kernel/rcu/tree.c Paul E. McKenney 2015-10-31 844 }
> 7c9906ca5 kernel/rcu/tree.c Paul E. McKenney 2015-10-31 845
> 7c9906ca5 kernel/rcu/tree.c Paul E. McKenney 2015-10-31 846 /*
> 7c9906ca5 kernel/rcu/tree.c Paul E. McKenney 2015-10-31 847 * Wrapper for rcu_irq_exit() where interrupts are enabled.
> c0da313e0 kernel/rcu/tree.c Paul E. McKenney 2017-09-22 848 *
> c0da313e0 kernel/rcu/tree.c Paul E. McKenney 2017-09-22 849 * If you add or remove a call to rcu_irq_exit_irqson(), be sure to test
> c0da313e0 kernel/rcu/tree.c Paul E. McKenney 2017-09-22 850 * with CONFIG_RCU_EQS_DEBUG=y.
> 7c9906ca5 kernel/rcu/tree.c Paul E. McKenney 2015-10-31 851 */
> 7c9906ca5 kernel/rcu/tree.c Paul E. McKenney 2015-10-31 852 void rcu_irq_exit_irqson(void)
> 7c9906ca5 kernel/rcu/tree.c Paul E. McKenney 2015-10-31 853 {
> 7c9906ca5 kernel/rcu/tree.c Paul E. McKenney 2015-10-31 854 unsigned long flags;
> 7c9906ca5 kernel/rcu/tree.c Paul E. McKenney 2015-10-31 855
> 7c9906ca5 kernel/rcu/tree.c Paul E. McKenney 2015-10-31 856 local_irq_save(flags);
> 7c9906ca5 kernel/rcu/tree.c Paul E. McKenney 2015-10-31 857 rcu_irq_exit();
> 23b5c8fa0 kernel/rcutree.c Paul E. McKenney 2010-09-07 858 local_irq_restore(flags);
> 9b2e4f188 kernel/rcutree.c Paul E. McKenney 2011-09-30 859 }
> 9b2e4f188 kernel/rcutree.c Paul E. McKenney 2011-09-30 860
> 9b2e4f188 kernel/rcutree.c Paul E. McKenney 2011-09-30 861 /*
> adf5091e6 kernel/rcutree.c Frederic Weisbecker 2012-06-28 862 * Exit an RCU extended quiescent state, which can be either the
> adf5091e6 kernel/rcutree.c Frederic Weisbecker 2012-06-28 863 * idle loop or adaptive-tickless usermode execution.
> 51a1fd30f kernel/rcu/tree.c Paul E. McKenney 2017-10-03 864 *
> 51a1fd30f kernel/rcu/tree.c Paul E. McKenney 2017-10-03 865 * We crowbar the ->dynticks_nmi_nesting field to DYNTICK_IRQ_NONIDLE to
> 51a1fd30f kernel/rcu/tree.c Paul E. McKenney 2017-10-03 866 * allow for the possibility of usermode upcalls messing up our count of
> 51a1fd30f kernel/rcu/tree.c Paul E. McKenney 2017-10-03 867 * interrupt nesting level during the busy period that is just now starting.
> 9b2e4f188 kernel/rcutree.c Paul E. McKenney 2011-09-30 868 */
> adf5091e6 kernel/rcutree.c Frederic Weisbecker 2012-06-28 869 static void rcu_eqs_exit(bool user)
> 9b2e4f188 kernel/rcutree.c Paul E. McKenney 2011-09-30 870 {
> 9b2e4f188 kernel/rcutree.c Paul E. McKenney 2011-09-30 871 struct rcu_dynticks *rdtp;
> 84585aa8b kernel/rcu/tree.c Paul E. McKenney 2017-10-04 872 long oldval;
> 9b2e4f188 kernel/rcutree.c Paul E. McKenney 2011-09-30 873
> b04db8e19 kernel/rcu/tree.c Frederic Weisbecker 2017-11-06 874 lockdep_assert_irqs_disabled();
> c9d4b0af9 kernel/rcutree.c Christoph Lameter 2013-08-31 875 rdtp = this_cpu_ptr(&rcu_dynticks);
> 9b2e4f188 kernel/rcutree.c Paul E. McKenney 2011-09-30 876 oldval = rdtp->dynticks_nesting;
> 1ce46ee59 kernel/rcu/tree.c Paul E. McKenney 2015-05-05 877 WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && oldval < 0);
> 51a1fd30f kernel/rcu/tree.c Paul E. McKenney 2017-10-03 878 if (oldval) {
> 51a1fd30f kernel/rcu/tree.c Paul E. McKenney 2017-10-03 879 rdtp->dynticks_nesting++;
> 9dd238e28 kernel/rcu/tree.c Paul E. McKenney 2017-10-05 880 return;
> 9b2e4f188 kernel/rcutree.c Paul E. McKenney 2011-09-30 881 }
> 9dd238e28 kernel/rcu/tree.c Paul E. McKenney 2017-10-05 882 rcu_dynticks_task_exit();
> 9dd238e28 kernel/rcu/tree.c Paul E. McKenney 2017-10-05 883 rcu_dynticks_eqs_exit();
> 9dd238e28 kernel/rcu/tree.c Paul E. McKenney 2017-10-05 884 rcu_cleanup_after_idle();
> 9dd238e28 kernel/rcu/tree.c Paul E. McKenney 2017-10-05 885 trace_rcu_dyntick(TPS("End"), rdtp->dynticks_nesting, 1, rdtp->dynticks);
> e68bbb266 kernel/rcu/tree.c Paul E. McKenney 2017-10-05 886 WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(current));
> 2342172fd kernel/rcu/tree.c Paul E. McKenney 2017-10-05 887 WRITE_ONCE(rdtp->dynticks_nesting, 1);
> 6136d6e48 kernel/rcu/tree.c Paul E. McKenney 2017-10-03 888 WRITE_ONCE(rdtp->dynticks_nmi_nesting, DYNTICK_IRQ_NONIDLE);
> 3a5924052 kernel/rcu/tree.c Paul E. McKenney 2013-10-04 889 }
> adf5091e6 kernel/rcutree.c Frederic Weisbecker 2012-06-28 890
> adf5091e6 kernel/rcutree.c Frederic Weisbecker 2012-06-28 891 /**
> adf5091e6 kernel/rcutree.c Frederic Weisbecker 2012-06-28 892 * rcu_idle_exit - inform RCU that current CPU is leaving idle
> adf5091e6 kernel/rcutree.c Frederic Weisbecker 2012-06-28 893 *
> adf5091e6 kernel/rcutree.c Frederic Weisbecker 2012-06-28 894 * Exit idle mode, in other words, -enter- the mode in which RCU
> adf5091e6 kernel/rcutree.c Frederic Weisbecker 2012-06-28 895 * read-side critical sections can occur.
> adf5091e6 kernel/rcutree.c Frederic Weisbecker 2012-06-28 896 *
> c0da313e0 kernel/rcu/tree.c Paul E. McKenney 2017-09-22 897 * If you add or remove a call to rcu_idle_exit(), be sure to test with
> c0da313e0 kernel/rcu/tree.c Paul E. McKenney 2017-09-22 898 * CONFIG_RCU_EQS_DEBUG=y.
> adf5091e6 kernel/rcutree.c Frederic Weisbecker 2012-06-28 899 */
> adf5091e6 kernel/rcutree.c Frederic Weisbecker 2012-06-28 900 void rcu_idle_exit(void)
> adf5091e6 kernel/rcutree.c Frederic Weisbecker 2012-06-28 901 {
> c5d900bf6 kernel/rcutree.c Frederic Weisbecker 2012-07-11 902 unsigned long flags;
> c5d900bf6 kernel/rcutree.c Frederic Weisbecker 2012-07-11 903
> c5d900bf6 kernel/rcutree.c Frederic Weisbecker 2012-07-11 904 local_irq_save(flags);
> cb349ca95 kernel/rcutree.c Paul E. McKenney 2012-09-04 905 rcu_eqs_exit(false);
> c5d900bf6 kernel/rcutree.c Frederic Weisbecker 2012-07-11 906 local_irq_restore(flags);
> adf5091e6 kernel/rcutree.c Frederic Weisbecker 2012-06-28 907 }
> 9b2e4f188 kernel/rcutree.c Paul E. McKenney 2011-09-30 908
> d1ec4c34c kernel/rcu/tree.c Paul E. McKenney 2015-05-13 909 #ifdef CONFIG_NO_HZ_FULL
> 9b2e4f188 kernel/rcutree.c Paul E. McKenney 2011-09-30 910 /**
> adf5091e6 kernel/rcutree.c Frederic Weisbecker 2012-06-28 911 * rcu_user_exit - inform RCU that we are exiting userspace.
> adf5091e6 kernel/rcutree.c Frederic Weisbecker 2012-06-28 912 *
> adf5091e6 kernel/rcutree.c Frederic Weisbecker 2012-06-28 913 * Exit RCU idle mode while entering the kernel because it can
> adf5091e6 kernel/rcutree.c Frederic Weisbecker 2012-06-28 914 * run a RCU read side critical section anytime.
> c0da313e0 kernel/rcu/tree.c Paul E. McKenney 2017-09-22 915 *
> c0da313e0 kernel/rcu/tree.c Paul E. McKenney 2017-09-22 916 * If you add or remove a call to rcu_user_exit(), be sure to test with
> c0da313e0 kernel/rcu/tree.c Paul E. McKenney 2017-09-22 917 * CONFIG_RCU_EQS_DEBUG=y.
> adf5091e6 kernel/rcutree.c Frederic Weisbecker 2012-06-28 918 */
> adf5091e6 kernel/rcutree.c Frederic Weisbecker 2012-06-28 919 void rcu_user_exit(void)
> adf5091e6 kernel/rcutree.c Frederic Weisbecker 2012-06-28 920 {
> 91d1aa43d kernel/rcutree.c Frederic Weisbecker 2012-11-27 921 rcu_eqs_exit(1);
> c5d900bf6 kernel/rcutree.c Frederic Weisbecker 2012-07-11 922 }
> d1ec4c34c kernel/rcu/tree.c Paul E. McKenney 2015-05-13 923 #endif /* CONFIG_NO_HZ_FULL */
> 19dd1591f kernel/rcutree.c Frederic Weisbecker 2012-06-04 924
> 19dd1591f kernel/rcutree.c Frederic Weisbecker 2012-06-04 925 /**
> 1e8a49734 kernel/rcu/tree.c Byungchul Park 2018-06-22 926 * rcu_nmi_enter_common - inform RCU of entry to NMI context
> 64db4cfff kernel/rcutree.c Paul E. McKenney 2008-12-18 927 *
> 734d16801 kernel/rcu/tree.c Paul E. McKenney 2014-11-21 928 * If the CPU was idle from RCU's viewpoint, update rdtp->dynticks and
> 734d16801 kernel/rcu/tree.c Paul E. McKenney 2014-11-21 929 * rdtp->dynticks_nmi_nesting to let the RCU grace-period handling know
> 734d16801 kernel/rcu/tree.c Paul E. McKenney 2014-11-21 930 * that the CPU is active. This implementation permits nested NMIs, as
> 734d16801 kernel/rcu/tree.c Paul E. McKenney 2014-11-21 931 * long as the nesting level does not overflow an int. (You will probably
> 734d16801 kernel/rcu/tree.c Paul E. McKenney 2014-11-21 932 * run out of stack space first.)
> c0da313e0 kernel/rcu/tree.c Paul E. McKenney 2017-09-22 933 *
> 1e8a49734 kernel/rcu/tree.c Byungchul Park 2018-06-22 934 * If you add or remove a call to rcu_nmi_enter_common(), be sure to test
> c0da313e0 kernel/rcu/tree.c Paul E. McKenney 2017-09-22 935 * with CONFIG_RCU_EQS_DEBUG=y.
> 64db4cfff kernel/rcutree.c Paul E. McKenney 2008-12-18 936 */
> 1e8a49734 kernel/rcu/tree.c Byungchul Park 2018-06-22 937 static __always_inline void rcu_nmi_enter_common(bool irq)
> 64db4cfff kernel/rcutree.c Paul E. McKenney 2008-12-18 @938 {
> c9d4b0af9 kernel/rcutree.c Christoph Lameter 2013-08-31 939 struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
> 84585aa8b kernel/rcu/tree.c Paul E. McKenney 2017-10-04 940 long incby = 2;
> 64db4cfff kernel/rcutree.c Paul E. McKenney 2008-12-18 941
> 734d16801 kernel/rcu/tree.c Paul E. McKenney 2014-11-21 942 /* Complain about underflow. */
> 734d16801 kernel/rcu/tree.c Paul E. McKenney 2014-11-21 943 WARN_ON_ONCE(rdtp->dynticks_nmi_nesting < 0);
> 734d16801 kernel/rcu/tree.c Paul E. McKenney 2014-11-21 944
> 734d16801 kernel/rcu/tree.c Paul E. McKenney 2014-11-21 945 /*
> 734d16801 kernel/rcu/tree.c Paul E. McKenney 2014-11-21 946 * If idle from RCU viewpoint, atomically increment ->dynticks
> 734d16801 kernel/rcu/tree.c Paul E. McKenney 2014-11-21 947 * to mark non-idle and increment ->dynticks_nmi_nesting by one.
> 734d16801 kernel/rcu/tree.c Paul E. McKenney 2014-11-21 948 * Otherwise, increment ->dynticks_nmi_nesting by two. This means
> 734d16801 kernel/rcu/tree.c Paul E. McKenney 2014-11-21 949 * if ->dynticks_nmi_nesting is equal to one, we are guaranteed
> 734d16801 kernel/rcu/tree.c Paul E. McKenney 2014-11-21 950 * to be in the outermost NMI handler that interrupted an RCU-idle
> 734d16801 kernel/rcu/tree.c Paul E. McKenney 2014-11-21 951 * period (observation due to Andy Lutomirski).
> 734d16801 kernel/rcu/tree.c Paul E. McKenney 2014-11-21 952 */
> 02a5c550b kernel/rcu/tree.c Paul E. McKenney 2016-11-02 953 if (rcu_dynticks_curr_cpu_in_eqs()) {
> 1e8a49734 kernel/rcu/tree.c Byungchul Park 2018-06-22 954
> 1e8a49734 kernel/rcu/tree.c Byungchul Park 2018-06-22 955 if (irq)
> 1e8a49734 kernel/rcu/tree.c Byungchul Park 2018-06-22 956 rcu_dynticks_task_exit();
> 1e8a49734 kernel/rcu/tree.c Byungchul Park 2018-06-22 957
> 2625d469b kernel/rcu/tree.c Paul E. McKenney 2016-11-02 958 rcu_dynticks_eqs_exit();
> 1e8a49734 kernel/rcu/tree.c Byungchul Park 2018-06-22 959
> 1e8a49734 kernel/rcu/tree.c Byungchul Park 2018-06-22 960 if (irq)
> 1e8a49734 kernel/rcu/tree.c Byungchul Park 2018-06-22 961 rcu_cleanup_after_idle();
> 1e8a49734 kernel/rcu/tree.c Byungchul Park 2018-06-22 962
> 734d16801 kernel/rcu/tree.c Paul E. McKenney 2014-11-21 963 incby = 1;
> 734d16801 kernel/rcu/tree.c Paul E. McKenney 2014-11-21 964 }
> bd2b879a1 kernel/rcu/tree.c Paul E. McKenney 2017-10-04 965 trace_rcu_dyntick(incby == 1 ? TPS("Endirq") : TPS("++="),
> bd2b879a1 kernel/rcu/tree.c Paul E. McKenney 2017-10-04 966 rdtp->dynticks_nmi_nesting,
> dec98900e kernel/rcu/tree.c Paul E. McKenney 2017-10-04 967 rdtp->dynticks_nmi_nesting + incby, rdtp->dynticks);
> fd581a91a kernel/rcu/tree.c Paul E. McKenney 2017-10-02 968 WRITE_ONCE(rdtp->dynticks_nmi_nesting, /* Prevent store tearing. */
> fd581a91a kernel/rcu/tree.c Paul E. McKenney 2017-10-02 969 rdtp->dynticks_nmi_nesting + incby);
> 734d16801 kernel/rcu/tree.c Paul E. McKenney 2014-11-21 970 barrier();
> 64db4cfff kernel/rcutree.c Paul E. McKenney 2008-12-18 971 }
> 64db4cfff kernel/rcutree.c Paul E. McKenney 2008-12-18 972
>
> :::::: The code at line 778 was first introduced by commit
> :::::: fd581a91ac16187625ec509414d08d37827472c4 rcu: Move rcu_nmi_{enter,exit}() to prepare for consolidation
>
> :::::: TO: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
> :::::: CC: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
>
> ---
> 0-DAY kernel test infrastructure Open Source Technology Center
> https://lists.01.org/pipermail/kbuild-all Intel Corporation

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