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/trace_output.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-) (limited to 'kernel/trace/trace_output.c') diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c index ea9d3b4..6a4c9de 100644 --- a/kernel/trace/trace_output.c +++ b/kernel/trace/trace_output.c @@ -309,9 +309,9 @@ static int lat_print_generic(struct trace_seq *s, struct trace_entry *entry, int cpu) { int hardirq, softirq; - char *comm; + char comm[TASK_COMM_LEN]; - comm = trace_find_cmdline(entry->pid); + trace_find_cmdline(entry->pid, comm); hardirq = entry->flags & TRACE_FLAG_HARDIRQ; softirq = entry->flags & TRACE_FLAG_SOFTIRQ; @@ -346,10 +346,12 @@ int trace_print_context(struct trace_iterator *iter) { struct trace_seq *s = &iter->seq; struct trace_entry *entry = iter->ent; - char *comm = trace_find_cmdline(entry->pid); unsigned long long t = ns2usecs(iter->ts); unsigned long usec_rem = do_div(t, USEC_PER_SEC); unsigned long secs = (unsigned long)t; + char comm[TASK_COMM_LEN]; + + trace_find_cmdline(entry->pid, comm); return trace_seq_printf(s, "%16s-%-5d [%03d] %5lu.%06lu: ", comm, entry->pid, iter->cpu, secs, usec_rem); @@ -372,7 +374,10 @@ int trace_print_lat_context(struct trace_iterator *iter) rel_usecs = ns2usecs(next_ts - iter->ts); if (verbose) { - char *comm = trace_find_cmdline(entry->pid); + char comm[TASK_COMM_LEN]; + + trace_find_cmdline(entry->pid, comm); + ret = trace_seq_printf(s, "%16s %5d %3d %d %08x %08lx [%08lx]" " %ld.%03ldms (+%ld.%03ldms): ", comm, entry->pid, iter->cpu, entry->flags, @@ -577,14 +582,15 @@ static enum print_line_t trace_ctxwake_print(struct trace_iterator *iter, char *delim) { struct ctx_switch_entry *field; - char *comm; + char comm[TASK_COMM_LEN]; int S, T; + trace_assign_type(field, iter->ent); T = task_state_char(field->next_state); S = task_state_char(field->prev_state); - comm = trace_find_cmdline(field->next_pid); + trace_find_cmdline(field->next_pid, comm); if (!trace_seq_printf(&iter->seq, " %5d:%3d:%c %s [%03d] %5d:%3d:%c %s\n", field->prev_pid, -- cgit v1.1