From 614e4c4ebc75517295bccd29b20ddbc5b52af6fc Mon Sep 17 00:00:00 2001 From: Stephane Eranian Date: Thu, 12 Nov 2015 11:00:04 +0100 Subject: perf/core: Robustify the perf_cgroup_from_task() RCU checks This patch reinforces the lockdep checks performed by perf_cgroup_from_tsk() by passing the perf_event_context whenever possible. It is okay to not hold the RCU read lock when we know we hold the ctx->lock. This patch makes sure this property holds. In some functions, such as perf_cgroup_sched_in(), we do not pass the context because we are sure we are holding the RCU read lock. Signed-off-by: Stephane Eranian Signed-off-by: Peter Zijlstra (Intel) Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Linus Torvalds Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Vince Weaver Cc: edumazet@google.com Link: http://lkml.kernel.org/r/1447322404-10920-3-git-send-email-eranian@google.com Signed-off-by: Ingo Molnar --- include/linux/perf_event.h | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'include/linux/perf_event.h') diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index d841d33bcdc9..f9828a48f16a 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -697,9 +697,11 @@ struct perf_cgroup { * if there is no cgroup event for the current CPU context. */ static inline struct perf_cgroup * -perf_cgroup_from_task(struct task_struct *task) +perf_cgroup_from_task(struct task_struct *task, struct perf_event_context *ctx) { - return container_of(task_css(task, perf_event_cgrp_id), + return container_of(task_css_check(task, perf_event_cgrp_id, + ctx ? lockdep_is_held(&ctx->lock) + : true), struct perf_cgroup, css); } #endif /* CONFIG_CGROUP_PERF */ -- cgit v1.2.3