From 592903cdcbf606a838056bae6d03fc557806c914 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Fri, 13 Mar 2009 12:21:36 +0100 Subject: [PATCH] perf_counter: add an event_list I noticed that the counter_list only includes top-level counters, thus perf_swcounter_event() will miss sw-counters in groups. Since perf_swcounter_event() also wants an RCU safe list, create a new event_list that includes all counters and uses RCU list ops and use call_rcu to free the counter structure. Signed-off-by: Peter Zijlstra Signed-off-by: Ingo Molnar --- include/linux/perf_counter.h | 4 ++++ kernel/perf_counter.c | 30 +++++++++++++++++++----------- 2 files changed, 23 insertions(+), 11 deletions(-) diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h index dfb4c7ce18b3..08c11a6afebc 100644 --- a/include/linux/perf_counter.h +++ b/include/linux/perf_counter.h @@ -187,6 +187,7 @@ struct file; struct perf_counter { #ifdef CONFIG_PERF_COUNTERS struct list_head list_entry; + struct list_head event_entry; struct list_head sibling_list; struct perf_counter *group_leader; const struct hw_perf_counter_ops *hw_ops; @@ -220,6 +221,8 @@ struct perf_counter { struct perf_data *irqdata; struct perf_data *usrdata; struct perf_data data[2]; + + struct rcu_head rcu_head; #endif }; @@ -243,6 +246,7 @@ struct perf_counter_context { struct mutex mutex; struct list_head counter_list; + struct list_head event_list; int nr_counters; int nr_active; int is_active; diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c index f9330d5827cf..8d6ecfa64c0e 100644 --- a/kernel/perf_counter.c +++ b/kernel/perf_counter.c @@ -22,6 +22,7 @@ #include #include #include +#include /* * Each CPU has a list of per CPU counters: @@ -72,6 +73,8 @@ list_add_counter(struct perf_counter *counter, struct perf_counter_context *ctx) list_add_tail(&counter->list_entry, &ctx->counter_list); else list_add_tail(&counter->list_entry, &group_leader->sibling_list); + + list_add_rcu(&counter->event_entry, &ctx->event_list); } static void @@ -80,6 +83,7 @@ list_del_counter(struct perf_counter *counter, struct perf_counter_context *ctx) struct perf_counter *sibling, *tmp; list_del_init(&counter->list_entry); + list_del_rcu(&counter->event_entry); /* * If this was a group counter with sibling counters then @@ -1133,6 +1137,14 @@ static struct perf_counter_context *find_get_context(pid_t pid, int cpu) return ctx; } +static void free_counter_rcu(struct rcu_head *head) +{ + struct perf_counter *counter; + + counter = container_of(head, struct perf_counter, rcu_head); + kfree(counter); +} + /* * Called when the last reference to the file is gone. */ @@ -1151,7 +1163,7 @@ static int perf_release(struct inode *inode, struct file *file) mutex_unlock(&counter->mutex); mutex_unlock(&ctx->mutex); - kfree(counter); + call_rcu(&counter->rcu_head, free_counter_rcu); put_context(ctx); return 0; @@ -1491,22 +1503,16 @@ static void perf_swcounter_ctx_event(struct perf_counter_context *ctx, int nmi, struct pt_regs *regs) { struct perf_counter *counter; - unsigned long flags; - if (list_empty(&ctx->counter_list)) + if (list_empty(&ctx->event_list)) return; - spin_lock_irqsave(&ctx->lock, flags); - - /* - * XXX: make counter_list RCU safe - */ - list_for_each_entry(counter, &ctx->counter_list, list_entry) { + rcu_read_lock(); + list_for_each_entry_rcu(counter, &ctx->event_list, event_entry) { if (perf_swcounter_match(counter, event, regs)) perf_swcounter_add(counter, nr, nmi, regs); } - - spin_unlock_irqrestore(&ctx->lock, flags); + rcu_read_unlock(); } void perf_swcounter_event(enum hw_event_types event, u64 nr, @@ -1846,6 +1852,7 @@ perf_counter_alloc(struct perf_counter_hw_event *hw_event, mutex_init(&counter->mutex); INIT_LIST_HEAD(&counter->list_entry); + INIT_LIST_HEAD(&counter->event_entry); INIT_LIST_HEAD(&counter->sibling_list); init_waitqueue_head(&counter->waitq); @@ -1992,6 +1999,7 @@ __perf_counter_init_context(struct perf_counter_context *ctx, spin_lock_init(&ctx->lock); mutex_init(&ctx->mutex); INIT_LIST_HEAD(&ctx->counter_list); + INIT_LIST_HEAD(&ctx->event_list); ctx->task = task; } -- 2.30.2