From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Sukadev Bhattiprolu Subject: [PATCH v5 6/8] perf: Add return value for perf_event_read(). Date: Thu, 13 Aug 2015 23:49:39 -0700 Message-Id: <1439534981-7937-7-git-send-email-sukadev@linux.vnet.ibm.com> In-Reply-To: <1439534981-7937-1-git-send-email-sukadev@linux.vnet.ibm.com> References: <1439534981-7937-1-git-send-email-sukadev@linux.vnet.ibm.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , List-Archive: To: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Michael Ellerman Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, sparclinux@vger.kernel.org List-ID: When we implement the ability to read several counters at once (using the PERF_PMU_TXN_READ transaction interface), perf_event_read() can fail when the 'group' parameter is true (eg: trying to read too many events at once). For now, have perf_event_read() return an integer. Ignore the return value when 'group' parameter is false. Signed-off-by: Sukadev Bhattiprolu --- kernel/events/core.c | 45 ++++++++++++++++++++++++++++++++++----------- 1 file changed, 34 insertions(+), 11 deletions(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index 2221ebe..e3ce047 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -3177,6 +3177,7 @@ void perf_event_exec(void) struct perf_read_data { struct perf_event *event; bool group; + int ret; }; /* @@ -3217,6 +3218,7 @@ static void __perf_event_read(void *info) if (sub->state == PERF_EVENT_STATE_ACTIVE) sub->pmu->read(sub); } + data->ret = 0; unlock: raw_spin_unlock(&ctx->lock); @@ -3230,8 +3232,10 @@ static inline u64 perf_event_count(struct perf_event *event) return __perf_event_count(event); } -static void perf_event_read(struct perf_event *event, bool group) +static int perf_event_read(struct perf_event *event, bool group) { + int ret = 0; + /* * If event is enabled and currently active on a CPU, update the * value in the event structure: @@ -3240,9 +3244,11 @@ static void perf_event_read(struct perf_event *event, bool group) struct perf_read_data data = { .event = event, .group = group, + .ret = 0, }; smp_call_function_single(event->oncpu, __perf_event_read, &data, 1); + ret = data.ret; } else if (event->state == PERF_EVENT_STATE_INACTIVE) { struct perf_event_context *ctx = event->ctx; unsigned long flags; @@ -3263,6 +3269,8 @@ static void perf_event_read(struct perf_event *event, bool group) update_event_times(event); raw_spin_unlock_irqrestore(&ctx->lock, flags); } + + return ret; } /* @@ -3775,7 +3783,7 @@ u64 perf_event_read_value(struct perf_event *event, u64 *enabled, u64 *running) mutex_lock(&event->child_mutex); - perf_event_read(event, false); + (void)perf_event_read(event, false); total += perf_event_count(event); *enabled += event->total_time_enabled + @@ -3784,7 +3792,7 @@ u64 perf_event_read_value(struct perf_event *event, u64 *enabled, u64 *running) atomic64_read(&event->child_total_time_running); list_for_each_entry(child, &event->child_list, child_list) { - perf_event_read(child, false); + (void)perf_event_read(child, false); total += perf_event_count(child); *enabled += child->total_time_enabled; *running += child->total_time_running; @@ -3795,13 +3803,16 @@ u64 perf_event_read_value(struct perf_event *event, u64 *enabled, u64 *running) } EXPORT_SYMBOL_GPL(perf_event_read_value); -static void __perf_read_group_add(struct perf_event *leader, +static int __perf_read_group_add(struct perf_event *leader, u64 read_format, u64 *values) { struct perf_event *sub; int n = 1; /* skip @nr */ + int ret; - perf_event_read(leader, true); + ret = perf_event_read(leader, true); + if (ret) + return ret; /* * Since we co-schedule groups, {enabled,running} times of siblings @@ -3830,6 +3841,8 @@ static void __perf_read_group_add(struct perf_event *leader, if (read_format & PERF_FORMAT_ID) values[n++] = primary_event_id(sub); } + + return 0; } static int perf_read_group(struct perf_event *event, @@ -3837,7 +3850,7 @@ static int perf_read_group(struct perf_event *event, { struct perf_event *leader = event->group_leader, *child; struct perf_event_context *ctx = leader->ctx; - int ret = event->read_size; + int ret; u64 *values; lockdep_assert_held(&ctx->mutex); @@ -3854,17 +3867,27 @@ static int perf_read_group(struct perf_event *event, */ mutex_lock(&leader->child_mutex); - __perf_read_group_add(leader, read_format, values); - list_for_each_entry(child, &leader->child_list, child_list) - __perf_read_group_add(child, read_format, values); + ret = __perf_read_group_add(leader, read_format, values); + if (ret) + goto unlock; + + list_for_each_entry(child, &leader->child_list, child_list) { + ret = __perf_read_group_add(child, read_format, values); + if (ret) + goto unlock; + } mutex_unlock(&leader->child_mutex); + ret = event->read_size; if (copy_to_user(buf, values, event->read_size)) ret = -EFAULT; + goto out; +unlock: + mutex_unlock(&leader->child_mutex); +out: kfree(values); - return ret; } @@ -3970,7 +3993,7 @@ static unsigned int perf_poll(struct file *file, poll_table *wait) static void _perf_event_reset(struct perf_event *event) { - perf_event_read(event, false); + (void)perf_event_read(event, false); local64_set(&event->count, 0); perf_event_update_userpage(event); } -- 1.7.9.5