From 8550d7cb6ed6c89add49c3b6ad4c753ab8a3d7f9 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Wed, 19 Jan 2011 19:22:28 +0100 Subject: [PATCH] perf: Fix perf_event_init_task()/perf_event_free_task() interaction perf_event_init_task() should clear child->perf_event_ctxp[] before anything else. Otherwise, if perf_event_init_context(perf_hw_context) fails, perf_event_free_task() can free perf_event_ctxp[perf_sw_context] copied from parent->perf_event_ctxp[] by dup_task_struct(). Also move the initialization of perf_event_mutex and perf_event_list from perf_event_init_context() to perf_event_init_context(). Signed-off-by: Oleg Nesterov Acked-by: Peter Zijlstra Cc: Alan Stern Cc: Arnaldo Carvalho de Melo Cc: Frederic Weisbecker Cc: Paul Mackerras Cc: Prasad Cc: Roland McGrath LKML-Reference: <20110119182228.GC12183@redhat.com> Signed-off-by: Ingo Molnar --- kernel/perf_event.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/kernel/perf_event.c b/kernel/perf_event.c index 4ec55ef5810c..244ca3acb0ee 100644 --- a/kernel/perf_event.c +++ b/kernel/perf_event.c @@ -6446,11 +6446,6 @@ int perf_event_init_context(struct task_struct *child, int ctxn) unsigned long flags; int ret = 0; - child->perf_event_ctxp[ctxn] = NULL; - - mutex_init(&child->perf_event_mutex); - INIT_LIST_HEAD(&child->perf_event_list); - if (likely(!parent->perf_event_ctxp[ctxn])) return 0; @@ -6539,6 +6534,10 @@ int perf_event_init_task(struct task_struct *child) { int ctxn, ret; + memset(child->perf_event_ctxp, 0, sizeof(child->perf_event_ctxp)); + mutex_init(&child->perf_event_mutex); + INIT_LIST_HEAD(&child->perf_event_list); + for_each_task_context_nr(ctxn) { ret = perf_event_init_context(child, ctxn); if (ret) -- 2.20.1