diff options
| -rw-r--r-- | sys/compat/linuxkpi/common/include/linux/sched.h | 4 | ||||
| -rw-r--r-- | sys/compat/linuxkpi/common/include/linux/srcu.h | 2 | ||||
| -rw-r--r-- | sys/compat/linuxkpi/common/src/linux_rcu.c | 356 |
3 files changed, 187 insertions, 175 deletions
diff --git a/sys/compat/linuxkpi/common/include/linux/sched.h b/sys/compat/linuxkpi/common/include/linux/sched.h index 4de6f9e28238..59900c12ab1d 100644 --- a/sys/compat/linuxkpi/common/include/linux/sched.h +++ b/sys/compat/linuxkpi/common/include/linux/sched.h @@ -37,7 +37,7 @@ #include <sys/sched.h> #include <sys/sleepqueue.h> -#include <linux/types.h> +#include <linux/list.h> #include <linux/compat.h> #include <linux/completion.h> #include <linux/pid.h> @@ -72,6 +72,8 @@ struct task_struct { unsigned bsd_ioctl_len; struct completion parked; struct completion exited; + TAILQ_ENTRY(task_struct) rcu_entry; + int rcu_recurse; }; #define current ({ \ diff --git a/sys/compat/linuxkpi/common/include/linux/srcu.h b/sys/compat/linuxkpi/common/include/linux/srcu.h index 90e2378a858e..f89fc82a8e1e 100644 --- a/sys/compat/linuxkpi/common/include/linux/srcu.h +++ b/sys/compat/linuxkpi/common/include/linux/srcu.h @@ -29,9 +29,7 @@ #ifndef _LINUX_SRCU_H_ #define _LINUX_SRCU_H_ -struct srcu_epoch_record; struct srcu_struct { - struct srcu_epoch_record *ss_epoch_record; }; #define srcu_dereference(ptr,srcu) ((__typeof(*(ptr)) *)(ptr)) diff --git a/sys/compat/linuxkpi/common/src/linux_rcu.c b/sys/compat/linuxkpi/common/src/linux_rcu.c index 7665125958d6..123f1b287064 100644 --- a/sys/compat/linuxkpi/common/src/linux_rcu.c +++ b/sys/compat/linuxkpi/common/src/linux_rcu.c @@ -38,6 +38,7 @@ __FBSDID("$FreeBSD$"); #include <sys/smp.h> #include <sys/queue.h> #include <sys/taskqueue.h> +#include <sys/kdb.h> #include <ck_epoch.h> @@ -45,26 +46,34 @@ __FBSDID("$FreeBSD$"); #include <linux/srcu.h> #include <linux/slab.h> #include <linux/kernel.h> +#include <linux/compat.h> -struct callback_head; -struct writer_epoch_record { - ck_epoch_record_t epoch_record; - struct mtx head_lock; - struct mtx sync_lock; - struct task task; - STAILQ_HEAD(, callback_head) head; -} __aligned(CACHE_LINE_SIZE); +/* + * By defining CONFIG_NO_RCU_SKIP LinuxKPI RCU locks and asserts will + * not be skipped during panic(). + */ +#ifdef CONFIG_NO_RCU_SKIP +#define RCU_SKIP(void) 0 +#else +#define RCU_SKIP(void) unlikely(SCHEDULER_STOPPED() || kdb_active) +#endif struct callback_head { STAILQ_ENTRY(callback_head) entry; rcu_callback_t func; }; -struct srcu_epoch_record { +struct linux_epoch_head { + STAILQ_HEAD(, callback_head) cb_head; + struct mtx lock; + struct task task; +} __aligned(CACHE_LINE_SIZE); + +struct linux_epoch_record { ck_epoch_record_t epoch_record; - struct mtx read_lock; - struct mtx sync_lock; -}; + TAILQ_HEAD(, task_struct) ts_head; + int cpuid; +} __aligned(CACHE_LINE_SIZE); /* * Verify that "struct rcu_head" is big enough to hold "struct @@ -72,57 +81,42 @@ struct srcu_epoch_record { * compile flags for including ck_epoch.h to all clients of the * LinuxKPI. */ -CTASSERT(sizeof(struct rcu_head) >= sizeof(struct callback_head)); +CTASSERT(sizeof(struct rcu_head) == sizeof(struct callback_head)); /* * Verify that "epoch_record" is at beginning of "struct - * writer_epoch_record": + * linux_epoch_record": */ -CTASSERT(offsetof(struct writer_epoch_record, epoch_record) == 0); - -/* - * Verify that "epoch_record" is at beginning of "struct - * srcu_epoch_record": - */ -CTASSERT(offsetof(struct srcu_epoch_record, epoch_record) == 0); +CTASSERT(offsetof(struct linux_epoch_record, epoch_record) == 0); static ck_epoch_t linux_epoch; -static MALLOC_DEFINE(M_LRCU, "lrcu", "Linux RCU"); -static DPCPU_DEFINE(ck_epoch_record_t *, linux_reader_epoch_record); -static DPCPU_DEFINE(struct writer_epoch_record *, linux_writer_epoch_record); +static struct linux_epoch_head linux_epoch_head; +static DPCPU_DEFINE(struct linux_epoch_record, linux_epoch_record); static void linux_rcu_cleaner_func(void *, int); static void linux_rcu_runtime_init(void *arg __unused) { + struct linux_epoch_head *head; int i; ck_epoch_init(&linux_epoch); - /* setup reader records */ - CPU_FOREACH(i) { - ck_epoch_record_t *record; - - record = malloc(sizeof(*record), M_LRCU, M_WAITOK | M_ZERO); - ck_epoch_register(&linux_epoch, record, NULL); + head = &linux_epoch_head; - DPCPU_ID_SET(i, linux_reader_epoch_record, record); - } + mtx_init(&head->lock, "LRCU-HEAD", NULL, MTX_DEF); + TASK_INIT(&head->task, 0, linux_rcu_cleaner_func, NULL); + STAILQ_INIT(&head->cb_head); - /* setup writer records */ CPU_FOREACH(i) { - struct writer_epoch_record *record; + struct linux_epoch_record *record; - record = malloc(sizeof(*record), M_LRCU, M_WAITOK | M_ZERO); + record = &DPCPU_ID_GET(i, linux_epoch_record); + record->cpuid = i; ck_epoch_register(&linux_epoch, &record->epoch_record, NULL); - mtx_init(&record->head_lock, "LRCU-HEAD", NULL, MTX_DEF); - mtx_init(&record->sync_lock, "LRCU-SYNC", NULL, MTX_DEF); - TASK_INIT(&record->task, 0, linux_rcu_cleaner_func, record); - STAILQ_INIT(&record->head); - - DPCPU_ID_SET(i, linux_writer_epoch_record, record); + TAILQ_INIT(&record->ts_head); } } SYSINIT(linux_rcu_runtime, SI_SUB_LOCK, SI_ORDER_SECOND, linux_rcu_runtime_init, NULL); @@ -130,91 +124,40 @@ SYSINIT(linux_rcu_runtime, SI_SUB_LOCK, SI_ORDER_SECOND, linux_rcu_runtime_init, static void linux_rcu_runtime_uninit(void *arg __unused) { - ck_stack_entry_t *cursor; - ck_stack_entry_t *next; - int i; + struct linux_epoch_head *head; - /* make sure all callbacks have been called */ - linux_rcu_barrier(); + head = &linux_epoch_head; - /* destroy all writer record mutexes */ - CPU_FOREACH(i) { - struct writer_epoch_record *record; - - record = DPCPU_ID_GET(i, linux_writer_epoch_record); - - mtx_destroy(&record->head_lock); - mtx_destroy(&record->sync_lock); - } - - /* free all registered reader and writer records */ - CK_STACK_FOREACH_SAFE(&linux_epoch.records, cursor, next) { - ck_epoch_record_t *record; - - record = container_of(cursor, - struct ck_epoch_record, record_next); - free(record, M_LRCU); - } + /* destroy head lock */ + mtx_destroy(&head->lock); } SYSUNINIT(linux_rcu_runtime, SI_SUB_LOCK, SI_ORDER_SECOND, linux_rcu_runtime_uninit, NULL); -static inline struct srcu_epoch_record * -linux_srcu_get_record(void) -{ - struct srcu_epoch_record *record; - - WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, - "linux_srcu_get_record() might sleep"); - - /* - * NOTE: The only records that are unregistered and can be - * recycled are srcu_epoch_records. - */ - record = (struct srcu_epoch_record *)ck_epoch_recycle(&linux_epoch, NULL); - if (__predict_true(record != NULL)) - return (record); - - record = malloc(sizeof(*record), M_LRCU, M_WAITOK | M_ZERO); - mtx_init(&record->read_lock, "SRCU-READ", NULL, MTX_DEF | MTX_NOWITNESS); - mtx_init(&record->sync_lock, "SRCU-SYNC", NULL, MTX_DEF | MTX_NOWITNESS); - ck_epoch_register(&linux_epoch, &record->epoch_record, NULL); - - return (record); -} - -static inline void -linux_rcu_synchronize_sub(struct writer_epoch_record *record) -{ - - /* protect access to epoch_record */ - mtx_lock(&record->sync_lock); - ck_epoch_synchronize(&record->epoch_record); - mtx_unlock(&record->sync_lock); -} - static void -linux_rcu_cleaner_func(void *context, int pending __unused) +linux_rcu_cleaner_func(void *context __unused, int pending __unused) { - struct writer_epoch_record *record; + struct linux_epoch_head *head; struct callback_head *rcu; - STAILQ_HEAD(, callback_head) head; + STAILQ_HEAD(, callback_head) tmp_head; - record = context; + linux_set_current(curthread); + + head = &linux_epoch_head; /* move current callbacks into own queue */ - mtx_lock(&record->head_lock); - STAILQ_INIT(&head); - STAILQ_CONCAT(&head, &record->head); - mtx_unlock(&record->head_lock); + mtx_lock(&head->lock); + STAILQ_INIT(&tmp_head); + STAILQ_CONCAT(&tmp_head, &head->cb_head); + mtx_unlock(&head->lock); /* synchronize */ - linux_rcu_synchronize_sub(record); + linux_synchronize_rcu(); /* dispatch all callbacks, if any */ - while ((rcu = STAILQ_FIRST(&head)) != NULL) { + while ((rcu = STAILQ_FIRST(&tmp_head)) != NULL) { uintptr_t offset; - STAILQ_REMOVE_HEAD(&head, entry); + STAILQ_REMOVE_HEAD(&tmp_head, entry); offset = (uintptr_t)rcu->func; @@ -228,148 +171,217 @@ linux_rcu_cleaner_func(void *context, int pending __unused) void linux_rcu_read_lock(void) { - ck_epoch_record_t *record; + struct linux_epoch_record *record; + struct task_struct *ts; + + if (RCU_SKIP()) + return; /* * Pin thread to current CPU so that the unlock code gets the - * same per-CPU reader epoch record: + * same per-CPU epoch record: */ sched_pin(); - record = DPCPU_GET(linux_reader_epoch_record); + record = &DPCPU_GET(linux_epoch_record); + ts = current; /* * Use a critical section to prevent recursion inside * ck_epoch_begin(). Else this function supports recursion. */ critical_enter(); - ck_epoch_begin(record, NULL); + ck_epoch_begin(&record->epoch_record, NULL); + ts->rcu_recurse++; + if (ts->rcu_recurse == 1) + TAILQ_INSERT_TAIL(&record->ts_head, ts, rcu_entry); critical_exit(); } void linux_rcu_read_unlock(void) { - ck_epoch_record_t *record; + struct linux_epoch_record *record; + struct task_struct *ts; - record = DPCPU_GET(linux_reader_epoch_record); + if (RCU_SKIP()) + return; + + record = &DPCPU_GET(linux_epoch_record); + ts = current; /* * Use a critical section to prevent recursion inside * ck_epoch_end(). Else this function supports recursion. */ critical_enter(); - ck_epoch_end(record, NULL); + ck_epoch_end(&record->epoch_record, NULL); + ts->rcu_recurse--; + if (ts->rcu_recurse == 0) + TAILQ_REMOVE(&record->ts_head, ts, rcu_entry); critical_exit(); sched_unpin(); } +static void +linux_synchronize_rcu_cb(ck_epoch_t *epoch __unused, ck_epoch_record_t *epoch_record, void *arg __unused) +{ + struct linux_epoch_record *record = + container_of(epoch_record, struct linux_epoch_record, epoch_record); + struct thread *td = curthread; + struct task_struct *ts; + + /* check if blocked on the current CPU */ + if (record->cpuid == PCPU_GET(cpuid)) { + bool is_sleeping = 0; + u_char prio = 0; + u_char old_prio; + + /* + * Find the lowest priority or sleeping thread which + * is blocking synchronization on this CPU core. All + * the threads in the queue are CPU-pinned and cannot + * go anywhere while the current thread is locked. + */ + TAILQ_FOREACH(ts, &record->ts_head, rcu_entry) { + if (ts->task_thread->td_priority > prio) + prio = ts->task_thread->td_priority; + is_sleeping |= (ts->task_thread->td_inhibitors != 0); + } + + if (is_sleeping) { + thread_unlock(td); + pause("W", 1); + thread_lock(td); + } else { + old_prio = td->td_priority; + /* set new thread priority */ + sched_prio(td, prio); + /* task switch */ + mi_switch(SW_VOL | SWT_RELINQUISH, NULL); + /* restore thread priority */ + sched_prio(td, old_prio); + } + } else { + /* + * To avoid spinning move execution to the other CPU + * which is blocking synchronization. Set highest + * thread priority so that code gets run. The thread + * priority will be restored later. + */ + sched_prio(td, 0); + sched_bind(td, record->cpuid); + } +} + void linux_synchronize_rcu(void) { - linux_rcu_synchronize_sub(DPCPU_GET(linux_writer_epoch_record)); + struct thread *td; + int was_bound; + int old_cpu; + int old_pinned; + + if (RCU_SKIP()) + return; + + WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, + "linux_synchronize_rcu() can sleep"); + + td = curthread; + + DROP_GIANT(); + + /* + * Synchronizing RCU might change the CPU core this function + * is running on. Save current values: + */ + thread_lock(td); + + old_cpu = PCPU_GET(cpuid); + old_pinned = td->td_pinned; + td->td_pinned = 0; + was_bound = sched_is_bound(td); + sched_bind(td, old_cpu); + + ck_epoch_synchronize_wait(&linux_epoch, + &linux_synchronize_rcu_cb, NULL); + + /* restore CPU binding, if any */ + if (was_bound != 0) { + sched_bind(td, old_cpu); + } else { + /* get thread back to initial CPU, if any */ + if (old_pinned != 0) + sched_bind(td, old_cpu); + sched_unbind(td); + } + /* restore pinned after bind */ + td->td_pinned = old_pinned; + thread_unlock(td); + + PICKUP_GIANT(); } void linux_rcu_barrier(void) { - int i; - - CPU_FOREACH(i) { - struct writer_epoch_record *record; + struct linux_epoch_head *head; - record = DPCPU_ID_GET(i, linux_writer_epoch_record); + linux_synchronize_rcu(); - linux_rcu_synchronize_sub(record); + head = &linux_epoch_head; - /* wait for callbacks to complete */ - taskqueue_drain(taskqueue_fast, &record->task); - } + /* wait for callbacks to complete */ + taskqueue_drain(taskqueue_fast, &head->task); } void linux_call_rcu(struct rcu_head *context, rcu_callback_t func) { struct callback_head *rcu = (struct callback_head *)context; - struct writer_epoch_record *record; - - record = DPCPU_GET(linux_writer_epoch_record); + struct linux_epoch_head *head = &linux_epoch_head; - mtx_lock(&record->head_lock); + mtx_lock(&head->lock); rcu->func = func; - STAILQ_INSERT_TAIL(&record->head, rcu, entry); - taskqueue_enqueue(taskqueue_fast, &record->task); - mtx_unlock(&record->head_lock); + STAILQ_INSERT_TAIL(&head->cb_head, rcu, entry); + taskqueue_enqueue(taskqueue_fast, &head->task); + mtx_unlock(&head->lock); } int init_srcu_struct(struct srcu_struct *srcu) { - struct srcu_epoch_record *record; - - record = linux_srcu_get_record(); - srcu->ss_epoch_record = record; return (0); } void cleanup_srcu_struct(struct srcu_struct *srcu) { - struct srcu_epoch_record *record; - - record = srcu->ss_epoch_record; - srcu->ss_epoch_record = NULL; - - ck_epoch_unregister(&record->epoch_record); } int srcu_read_lock(struct srcu_struct *srcu) { - struct srcu_epoch_record *record; - - record = srcu->ss_epoch_record; - - mtx_lock(&record->read_lock); - ck_epoch_begin(&record->epoch_record, NULL); - mtx_unlock(&record->read_lock); - + linux_rcu_read_lock(); return (0); } void srcu_read_unlock(struct srcu_struct *srcu, int key __unused) { - struct srcu_epoch_record *record; - - record = srcu->ss_epoch_record; - - mtx_lock(&record->read_lock); - ck_epoch_end(&record->epoch_record, NULL); - mtx_unlock(&record->read_lock); + linux_rcu_read_unlock(); } void synchronize_srcu(struct srcu_struct *srcu) { - struct srcu_epoch_record *record; - - record = srcu->ss_epoch_record; - - mtx_lock(&record->sync_lock); - ck_epoch_synchronize(&record->epoch_record); - mtx_unlock(&record->sync_lock); + linux_synchronize_rcu(); } void srcu_barrier(struct srcu_struct *srcu) { - struct srcu_epoch_record *record; - - record = srcu->ss_epoch_record; - - mtx_lock(&record->sync_lock); - ck_epoch_barrier(&record->epoch_record); - mtx_unlock(&record->sync_lock); + linux_rcu_barrier(); } |