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authorSteven Rostedt <srostedt@redhat.com>2009-03-16 19:20:15 -0400
committerSteven Rostedt <srostedt@redhat.com>2009-03-16 23:27:06 -0400
commit4ca530852346be239b7c19e7bec5d2b78855bebe (patch)
tree96e5252faaf362115a96ed6df7c4e4f698a027dc /kernel/trace/blktrace.c
parent03303549b1695dc024d4a653cc16bd79f78f9750 (diff)
tracing: protect reader of cmdline output
Impact: fix to one cause of incorrect comm outputs in trace The spinlock only protected the creation of a comm <=> pid pair. But it was possible that a reader could look up a pid, and get the wrong comm because it had no locking. This also required changing trace_find_cmdline to copy the comm cache and not just send back a pointer to it. Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Diffstat (limited to 'kernel/trace/blktrace.c')
-rw-r--r--kernel/trace/blktrace.c23
1 files changed, 18 insertions, 5 deletions
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index 1f32e4edf49..b171778e386 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -1027,7 +1027,9 @@ static int blk_log_action_seq(struct trace_seq *s, const struct blk_io_trace *t,
static int blk_log_generic(struct trace_seq *s, const struct trace_entry *ent)
{
- const char *cmd = trace_find_cmdline(ent->pid);
+ char cmd[TASK_COMM_LEN];
+
+ trace_find_cmdline(ent->pid, cmd);
if (t_sec(ent))
return trace_seq_printf(s, "%llu + %u [%s]\n",
@@ -1057,19 +1059,30 @@ static int blk_log_remap(struct trace_seq *s, const struct trace_entry *ent)
static int blk_log_plug(struct trace_seq *s, const struct trace_entry *ent)
{
- return trace_seq_printf(s, "[%s]\n", trace_find_cmdline(ent->pid));
+ char cmd[TASK_COMM_LEN];
+
+ trace_find_cmdline(ent->pid, cmd);
+
+ return trace_seq_printf(s, "[%s]\n", cmd);
}
static int blk_log_unplug(struct trace_seq *s, const struct trace_entry *ent)
{
- return trace_seq_printf(s, "[%s] %llu\n", trace_find_cmdline(ent->pid),
- get_pdu_int(ent));
+ char cmd[TASK_COMM_LEN];
+
+ trace_find_cmdline(ent->pid, cmd);
+
+ return trace_seq_printf(s, "[%s] %llu\n", cmd, get_pdu_int(ent));
}
static int blk_log_split(struct trace_seq *s, const struct trace_entry *ent)
{
+ char cmd[TASK_COMM_LEN];
+
+ trace_find_cmdline(ent->pid, cmd);
+
return trace_seq_printf(s, "%llu / %llu [%s]\n", t_sector(ent),
- get_pdu_int(ent), trace_find_cmdline(ent->pid));
+ get_pdu_int(ent), cmd);
}
/*