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| author | Steven Rostedt | 2009-03-17 00:20:15 +0100 |
|---|---|---|
| committer | Steven Rostedt | 2009-03-17 04:27:06 +0100 |
| commit | 4ca530852346be239b7c19e7bec5d2b78855bebe (patch) | |
| tree | 96e5252faaf362115a96ed6df7c4e4f698a027dc /kernel/trace/trace.c | |
| parent | tracing/ftrace: fix the check on nopped sites (diff) | |
| download | kernel-qcow2-linux-4ca530852346be239b7c19e7bec5d2b78855bebe.tar.gz kernel-qcow2-linux-4ca530852346be239b7c19e7bec5d2b78855bebe.tar.xz kernel-qcow2-linux-4ca530852346be239b7c19e7bec5d2b78855bebe.zip | |
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/trace.c')
| -rw-r--r-- | kernel/trace/trace.c | 20 |
1 files changed, 12 insertions, 8 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index efe3202c0209..2796bd2b17e4 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -770,25 +770,29 @@ static void trace_save_cmdline(struct task_struct *tsk) __raw_spin_unlock(&trace_cmdline_lock); } -char *trace_find_cmdline(int pid) +void trace_find_cmdline(int pid, char comm[]) { - char *cmdline = "<...>"; unsigned map; - if (!pid) - return "<idle>"; + if (!pid) { + strcpy(comm, "<idle>"); + return; + } - if (pid > PID_MAX_DEFAULT) - goto out; + if (pid > PID_MAX_DEFAULT) { + strcpy(comm, "<...>"); + return; + } + __raw_spin_lock(&trace_cmdline_lock); map = map_pid_to_cmdline[pid]; if (map >= SAVED_CMDLINES) goto out; - cmdline = saved_cmdlines[map]; + strcpy(comm, saved_cmdlines[map]); out: - return cmdline; + __raw_spin_unlock(&trace_cmdline_lock); } void tracing_record_cmdline(struct task_struct *tsk) |