From e6d9491bf8ba6728cc86aeabbc688d20ec0563b5 Mon Sep 17 00:00:00 2001 From: Li Zefan Date: Wed, 30 Dec 2009 14:23:40 +0800 Subject: [PATCH] ksym_tracer: Fix race when incrementing count We are under rcu read section but not holding the write lock, so count++ is not atomic. Use atomic64_t instead. Signed-off-by: Li Zefan Cc: Steven Rostedt Cc: K.Prasad Cc: Frederic Weisbecker LKML-Reference: <4B3AF1EC.9010608@cn.fujitsu.com> Signed-off-by: Ingo Molnar --- kernel/trace/trace_ksym.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/kernel/trace/trace_ksym.c b/kernel/trace/trace_ksym.c index 160a8d8b37a2..67d79f709fc5 100644 --- a/kernel/trace/trace_ksym.c +++ b/kernel/trace/trace_ksym.c @@ -32,6 +32,8 @@ #include #include +#include + /* * For now, let us restrict the no. of symbols traced simultaneously to number * of available hardware breakpoint registers. @@ -44,7 +46,7 @@ struct trace_ksym { struct perf_event **ksym_hbp; struct perf_event_attr attr; #ifdef CONFIG_PROFILE_KSYM_TRACER - unsigned long counter; + atomic64_t counter; #endif struct hlist_node ksym_hlist; }; @@ -69,9 +71,8 @@ void ksym_collect_stats(unsigned long hbp_hit_addr) rcu_read_lock(); hlist_for_each_entry_rcu(entry, node, &ksym_filter_head, ksym_hlist) { - if ((entry->attr.bp_addr == hbp_hit_addr) && - (entry->counter <= MAX_UL_INT)) { - entry->counter++; + if (entry->attr.bp_addr == hbp_hit_addr) { + atomic64_inc(&entry->counter); break; } } @@ -501,7 +502,8 @@ static int ksym_tracer_stat_show(struct seq_file *m, void *v) seq_printf(m, " %-36s", fn_name); else seq_printf(m, " %-36s", ""); - seq_printf(m, " %15lu\n", entry->counter); + seq_printf(m, " %15llu\n", + (unsigned long long)atomic64_read(&entry->counter)); return 0; } -- 2.20.1