From 4ca530852346be239b7c19e7bec5d2b78855bebe Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Mon, 16 Mar 2009 19:20:15 -0400 Subject: 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 --- kernel/trace/blktrace.c | 23 ++++++++++++++++++----- 1 file changed, 18 insertions(+), 5 deletions(-) (limited to 'kernel/trace/blktrace.c') 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); } /* -- cgit v1.2.3