On Tue, 02/03 13:52, Paolo Bonzini wrote: > From: Mike Day <ncm...@ncultra.org> > > Add RCU-enabled variants on the existing bsd DQ facility. Each > operation has the same interface as the existing (non-RCU) > version. Also, each operation is implemented as macro. > > Using the RCU-enabled QLIST, existing QLIST users will be able to > convert to RCU without using a different list interface. > > Signed-off-by: Mike Day <ncm...@ncultra.org> > Signed-off-by: Paolo Bonzini <pbonz...@redhat.com> > --- > hw/9pfs/virtio-9p-synth.c | 2 +- > include/qemu/queue.h | 11 -- > include/qemu/rcu_queue.h | 134 ++++++++++++++++++++ > tests/Makefile | 5 +- > tests/test-rcu-list.c | 306 > ++++++++++++++++++++++++++++++++++++++++++++++ > 5 files changed, 445 insertions(+), 13 deletions(-) > create mode 100644 include/qemu/rcu_queue.h > create mode 100644 tests/test-rcu-list.c > > diff --git a/hw/9pfs/virtio-9p-synth.c b/hw/9pfs/virtio-9p-synth.c > index e75aa87..a0ab9a8 100644 > --- a/hw/9pfs/virtio-9p-synth.c > +++ b/hw/9pfs/virtio-9p-synth.c > @@ -18,7 +18,7 @@ > #include "fsdev/qemu-fsdev.h" > #include "virtio-9p-synth.h" > #include "qemu/rcu.h" > - > +#include "qemu/rcu_queue.h" > #include <sys/stat.h> > > /* Root node for synth file system */ > diff --git a/include/qemu/queue.h b/include/qemu/queue.h > index c602797..8094150 100644 > --- a/include/qemu/queue.h > +++ b/include/qemu/queue.h > @@ -139,17 +139,6 @@ struct { > \ > (elm)->field.le_prev = &(head)->lh_first; \ > } while (/*CONSTCOND*/0) > > -#define QLIST_INSERT_HEAD_RCU(head, elm, field) do { \ > - (elm)->field.le_prev = &(head)->lh_first; \ > - (elm)->field.le_next = (head)->lh_first; \ > - smp_wmb(); /* fill elm before linking it */ \ > - if ((head)->lh_first != NULL) { \ > - (head)->lh_first->field.le_prev = &(elm)->field.le_next; \ > - } \ > - (head)->lh_first = (elm); \ > - smp_wmb(); \ > -} while (/* CONSTCOND*/0) > - > #define QLIST_REMOVE(elm, field) do { \ > if ((elm)->field.le_next != NULL) \ > (elm)->field.le_next->field.le_prev = \ > diff --git a/include/qemu/rcu_queue.h b/include/qemu/rcu_queue.h > new file mode 100644 > index 0000000..3aca7a5 > --- /dev/null > +++ b/include/qemu/rcu_queue.h > @@ -0,0 +1,134 @@ > +#ifndef QEMU_RCU_QUEUE_H > +#define QEMU_RCU_QUEUE_H > + > +/* > + * rcu_queue.h > + * > + * RCU-friendly versions of the queue.h primitives. > + * > + * This library is free software; you can redistribute it and/or > + * modify it under the terms of the GNU Lesser General Public > + * License as published by the Free Software Foundation; either > + * version 2.1 of the License, or (at your option) any later version. > + * > + * This library is distributed in the hope that it will be useful, > + * but WITHOUT ANY WARRANTY; without even the implied warranty of > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU > + * Lesser General Public License for more details. > + * > + * You should have received a copy of the GNU Lesser General Public > + * License along with this library; if not, write to the Free Software > + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 > USA > + * > + * Copyright (c) 2013 Mike D. Day, IBM Corporation. > + * > + * IBM's contributions to this file may be relicensed under LGPLv2 or later. > + */ > + > +#include "qemu/queue.h" > +#include "qemu/atomic.h" > + > +#ifdef __cplusplus > +extern "C" { > +#endif > + > + > +/* > + * List access methods. > + */ > +#define QLIST_EMPTY_RCU(head) (atomic_rcu_read(&(head)->lh_first) == NULL) > +#define QLIST_FIRST_RCU(head) (atomic_rcu_read(&(head)->lh_first)) > +#define QLIST_NEXT_RCU(elm, field) (atomic_rcu_read(&(elm)->field.le_next)) > + > +/* > + * List functions. > + */ > + > + > +/* > + * The difference between atomic_read/set and atomic_rcu_read/set > + * is in the including of a read/write memory barrier to the volatile > + * access. atomic_rcu_* macros include the memory barrier, the > + * plain atomic macros do not. Therefore, it should be correct to > + * issue a series of reads or writes to the same element using only > + * the atomic_* macro, until the last read or write, which should be > + * atomic_rcu_* to introduce a read or write memory barrier as > + * appropriate. > + */ > + > +/* Upon publication of the listelm->next value, list readers > + * will see the new node when following next pointers from > + * antecedent nodes, but may not see the new node when following > + * prev pointers from subsequent nodes until after the RCU grace > + * period expires. > + * see linux/include/rculist.h __list_add_rcu(new, prev, next) > + */ > +#define QLIST_INSERT_AFTER_RCU(listelm, elm, field) do { \ > + (elm)->field.le_next = (listelm)->field.le_next; \ > + (elm)->field.le_prev = &(listelm)->field.le_next; \ > + atomic_rcu_set(&(listelm)->field.le_next, (elm)); \ > + if ((elm)->field.le_next != NULL) { \ > + (elm)->field.le_next->field.le_prev = \ > + &(elm)->field.le_next; \ > + } \ > +} while (/*CONSTCOND*/0) > + > +/* Upon publication of the listelm->prev->next value, list > + * readers will see the new element when following prev pointers > + * from subsequent elements, but may not see the new element > + * when following next pointers from antecedent elements > + * until after the RCU grace period expires. > + */ > +#define QLIST_INSERT_BEFORE_RCU(listelm, elm, field) do { \ > + (elm)->field.le_prev = (listelm)->field.le_prev; \ > + (elm)->field.le_next = (listelm); \ > + atomic_rcu_set((listelm)->field.le_prev, (elm)); \ > + (listelm)->field.le_prev = &(elm)->field.le_next; \ > +} while (/*CONSTCOND*/0) > + > +/* Upon publication of the head->first value, list readers > + * will see the new element when following the head, but may > + * not see the new element when following prev pointers from > + * subsequent elements until after the RCU grace period has > + * expired. > + */ > +#define QLIST_INSERT_HEAD_RCU(head, elm, field) do { \ > + (elm)->field.le_prev = &(head)->lh_first; \ > + (elm)->field.le_next = (head)->lh_first; \ > + atomic_rcu_set((&(head)->lh_first), (elm)); \ > + if ((elm)->field.le_next != NULL) { \ > + (elm)->field.le_next->field.le_prev = \ > + &(elm)->field.le_next; \ > + } \ > +} while (/*CONSTCOND*/0) > + > + > +/* prior to publication of the elm->prev->next value, some list > + * readers may still see the removed element when following > + * the antecedent's next pointer. > + */ > +#define QLIST_REMOVE_RCU(elm, field) do { \ > + if ((elm)->field.le_next != NULL) { \ > + (elm)->field.le_next->field.le_prev = \ > + (elm)->field.le_prev; \ > + } \ > + *(elm)->field.le_prev = (elm)->field.le_next; \ > +} while (/*CONSTCOND*/0) > + > +/* List traversal must occur within an RCU critical section. */ > +#define QLIST_FOREACH_RCU(var, head, field) \ > + for ((var) = atomic_rcu_read(&(head)->lh_first); \ > + (var); \ > + (var) = atomic_rcu_read(&(var)->field.le_next)) > + > +/* List traversal must occur within an RCU critical section. */ > +#define QLIST_FOREACH_SAFE_RCU(var, head, field, next_var) \ > + for ((var) = (atomic_rcu_read(&(head)->lh_first)); \ > + (var) && \ > + ((next_var) = atomic_rcu_read(&(var)->field.le_next), 1); \ > + (var) = (next_var)) > + > +#ifdef __cplusplus > +} > +#endif > +#endif /* QEMU_RCU_QUEUE.H */ > diff --git a/tests/Makefile b/tests/Makefile > index db5b3c3..ef8d589 100644 > --- a/tests/Makefile > +++ b/tests/Makefile > @@ -62,6 +62,8 @@ check-unit-y += tests/test-int128$(EXESUF) > gcov-files-test-int128-y = > check-unit-y += tests/rcutorture$(EXESUF) > gcov-files-rcutorture-y = util/rcu.c > +check-unit-y += tests/test-rcu-list$(EXESUF) > +gcov-files-test-rcu-list-y = util/rcu.c > check-unit-y += tests/test-bitops$(EXESUF) > check-unit-$(CONFIG_HAS_GLIB_SUBPROCESS_TESTS) += > tests/test-qdev-global-props$(EXESUF) > check-unit-y += tests/check-qom-interface$(EXESUF) > @@ -226,7 +228,7 @@ test-obj-y = tests/check-qint.o tests/check-qstring.o > tests/check-qdict.o \ > tests/test-qmp-commands.o tests/test-visitor-serialization.o \ > tests/test-x86-cpuid.o tests/test-mul64.o tests/test-int128.o \ > tests/test-opts-visitor.o tests/test-qmp-event.o \ > - tests/rcutorture.o > + tests/rcutorture.o tests/test-rcu-list.o > > test-qapi-obj-y = tests/test-qapi-visit.o tests/test-qapi-types.o \ > tests/test-qapi-event.o > @@ -256,6 +258,7 @@ tests/test-xbzrle$(EXESUF): tests/test-xbzrle.o > migration/xbzrle.o page_cache.o > tests/test-cutils$(EXESUF): tests/test-cutils.o util/cutils.o > tests/test-int128$(EXESUF): tests/test-int128.o > tests/rcutorture$(EXESUF): tests/rcutorture.o libqemuutil.a > +tests/test-rcu-list$(EXESUF): tests/test-rcu-list.o libqemuutil.a > > tests/test-qdev-global-props$(EXESUF): tests/test-qdev-global-props.o \ > hw/core/qdev.o hw/core/qdev-properties.o hw/core/hotplug.o\ > diff --git a/tests/test-rcu-list.c b/tests/test-rcu-list.c > new file mode 100644 > index 0000000..5ce55e9 > --- /dev/null > +++ b/tests/test-rcu-list.c > @@ -0,0 +1,306 @@ > +/* > + * rcuq_test.c > + * > + * usage: rcuq_test <readers> <duration> > + * > + * This program is free software; you can redistribute it and/or modify > + * it under the terms of the GNU General Public License as published by > + * the Free Software Foundation; either version 2 of the License, or > + * (at your option) any later version. > + * > + * This program is distributed in the hope that it will be useful, > + * but WITHOUT ANY WARRANTY; without even the implied warranty of > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the > + * GNU General Public License for more details. > + * > + * You should have received a copy of the GNU General Public License > + * along with this program; if not, write to the Free Software > + * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. > + * > + * Copyright (c) 2013 Mike D. Day, IBM Corporation. > + */ > + > +/* > + * Test variables. > + */
Move below the includes? > + > +#include <glib.h> > +#include <stdlib.h> > +#include <stdio.h> > +#include <string.h> > +#include "qemu/atomic.h" > +#include "qemu/rcu.h" > +#include "qemu/compiler.h" > +#include "qemu/osdep.h" > +#include "qemu/thread.h" > +#include "qemu/rcu_queue.h" > + > +long long n_reads = 0LL; > +long long n_updates = 0LL; > +long long n_reclaims = 0LL; > +long long n_nodes_removed = 0LL; > +long long n_nodes = 0LL; > +int g_test_in_charge = 0; > + > +int nthreadsrunning; > + > +char argsbuf[64]; > + > +#define GOFLAG_INIT 0 > +#define GOFLAG_RUN 1 > +#define GOFLAG_STOP 2 > + > +static volatile int goflag = GOFLAG_INIT; > + > +#define RCU_READ_RUN 1000 > +#define RCU_UPDATE_RUN 10 > +#define NR_THREADS 100 > +#define RCU_Q_LEN 100 > + > +static QemuThread threads[NR_THREADS]; > +static struct rcu_reader_data *data[NR_THREADS]; > +static int n_threads; > + > +static int select_random_el(int max) > +{ > + return (rand() % max); > +} > + > + > +static void create_thread(void *(*func)(void *)) > +{ > + if (n_threads >= NR_THREADS) { > + fprintf(stderr, "Thread limit of %d exceeded!\n", NR_THREADS); > + exit(-1); > + } > + qemu_thread_create(&threads[n_threads], "test", func, &data[n_threads], > + QEMU_THREAD_JOINABLE); > + n_threads++; > +} > + > +static void wait_all_threads(void) > +{ > + int i; > + > + for (i = 0; i < n_threads; i++) { > + qemu_thread_join(&threads[i]); > + } > + n_threads = 0; > +} > + > + > +struct list_element { > + QLIST_ENTRY(list_element) entry; > + struct rcu_head rcu; > + long long val; > +}; > + > +static void reclaim_list_el(struct rcu_head *prcu) > +{ > + struct list_element *el = container_of(prcu, struct list_element, rcu); > + g_free(el); > + atomic_add(&n_reclaims, 1); > +} > + > +static QLIST_HEAD(q_list_head, list_element) Q_list_head; > + > +static void *rcu_q_reader(void *arg) > +{ > + long long j, n_reads_local = 0; > + struct list_element *el; > + > + *(struct rcu_reader_data **)arg = &rcu_reader; > + atomic_inc(&nthreadsrunning); > + while (goflag == GOFLAG_INIT) { > + g_usleep(1000); > + } > + > + while (goflag == GOFLAG_RUN) { > + rcu_read_lock(); > + QLIST_FOREACH_RCU(el, &Q_list_head, entry) { > + j = atomic_read(&el->val); > + (void)j; > + n_reads_local++; > + if (goflag == GOFLAG_STOP) { > + break; > + } > + } > + rcu_read_unlock(); > + > + g_usleep(100); > + } > + atomic_add(&n_reads, n_reads_local); > + return NULL; > +} > + > + > +static void *rcu_q_updater(void *arg) > +{ > + int j, target_el; > + long long n_updates_local = 0; > + long long n_removed_local = 0; > + struct list_element *el, *prev_el; > + > + *(struct rcu_reader_data **)arg = &rcu_reader; > + atomic_inc(&nthreadsrunning); > + while (goflag == GOFLAG_INIT) { > + g_usleep(1000); > + } > + > + while (goflag == GOFLAG_RUN) { > + target_el = select_random_el(RCU_Q_LEN); > + j = 0; > + /* FOREACH_RCU could work here but let's use both macros */ > + QLIST_FOREACH_SAFE_RCU(prev_el, &Q_list_head, entry, el) { > + j++; > + if (target_el == j) { > + QLIST_REMOVE_RCU(prev_el, entry); > + /* may be more than one updater in the future */ > + call_rcu1(&prev_el->rcu, reclaim_list_el); > + n_removed_local++; > + break; > + } > + } > + if (goflag == GOFLAG_STOP) { > + break; > + } > + target_el = select_random_el(RCU_Q_LEN); > + j = 0; > + QLIST_FOREACH_RCU(el, &Q_list_head, entry) { > + j++; > + if (target_el == j) { > + prev_el = g_new(struct list_element, 1); > + atomic_add(&n_nodes, 1); > + prev_el->val = atomic_read(&n_nodes); > + QLIST_INSERT_BEFORE_RCU(el, prev_el, entry); > + break; > + } > + } > + > + n_updates_local += 2; > + synchronize_rcu(); > + } > + synchronize_rcu(); Is one of two synchronize_rcu's superfluous? Otherwise looks good: Reviewed-by: Fam Zheng <f...@redhat.com> > + atomic_add(&n_updates, n_updates_local); > + atomic_add(&n_nodes_removed, n_removed_local); > + return NULL; > +} <...>