diff options
| author | Li Zefan <lizf@cn.fujitsu.com> | 2009-12-30 14:23:40 +0800 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-12-30 07:50:49 +0100 |
| commit | e6d9491bf8ba6728cc86aeabbc688d20ec0563b5 (patch) | |
| tree | 1ca34f9f0608f688069da43688b2a9b8fa163644 /kernel | |
| parent | 3d13ec2efdb5843ad91e57b60d50b44d922cf063 (diff) | |
| download | lwn-e6d9491bf8ba6728cc86aeabbc688d20ec0563b5.tar.gz lwn-e6d9491bf8ba6728cc86aeabbc688d20ec0563b5.zip | |
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 <lizf@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: K.Prasad <prasad@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <4B3AF1EC.9010608@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/trace/trace_ksym.c | 12 |
1 files 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 <linux/hw_breakpoint.h> #include <asm/hw_breakpoint.h> +#include <asm/atomic.h> + /* * 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", "<NA>"); - seq_printf(m, " %15lu\n", entry->counter); + seq_printf(m, " %15llu\n", + (unsigned long long)atomic64_read(&entry->counter)); return 0; } |