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authorMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>2013-05-09 14:44:17 +0900
committerSteven Rostedt <rostedt@goodmis.org>2013-05-09 20:10:22 -0400
commitf04f24fb7e48d446bd89a01c6056571f25972511 (patch)
treeb1d1ecbe88df0eee0309970fd07dc37fb375a440 /include
parent7c088b5120ffef017e2ddc38f992277e96436ef6 (diff)
ftrace, kprobes: Fix a deadlock on ftrace_regex_lock
Fix a deadlock on ftrace_regex_lock which happens when setting an enable_event trigger on dynamic kprobe event as below. ---- sh-2.05b# echo p vfs_symlink > kprobe_events sh-2.05b# echo vfs_symlink:enable_event:kprobes:p_vfs_symlink_0 > set_ftrace_filter ============================================= [ INFO: possible recursive locking detected ] 3.9.0+ #35 Not tainted --------------------------------------------- sh/72 is trying to acquire lock: (ftrace_regex_lock){+.+.+.}, at: [<ffffffff810ba6c1>] ftrace_set_hash+0x81/0x1f0 but task is already holding lock: (ftrace_regex_lock){+.+.+.}, at: [<ffffffff810b7cbd>] ftrace_regex_write.isra.29.part.30+0x3d/0x220 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(ftrace_regex_lock); lock(ftrace_regex_lock); *** DEADLOCK *** ---- To fix that, this introduces a finer regex_lock for each ftrace_ops. ftrace_regex_lock is too big of a lock which protects all filter/notrace_hash operations, but it doesn't need to be a global lock after supporting multiple ftrace_ops because each ftrace_ops has its own filter/notrace_hash. Link: http://lkml.kernel.org/r/20130509054417.30398.84254.stgit@mhiramat-M0-7522 Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Tom Zanussi <tom.zanussi@intel.com> Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> [ Added initialization flag and automate mutex initialization for non ftrace.c ftrace_probes. ] Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/ftrace.h4
1 files changed, 4 insertions, 0 deletions
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index f83e17a40e8..99d0fbcbaf7 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -90,6 +90,8 @@ typedef void (*ftrace_func_t)(unsigned long ip, unsigned long parent_ip,
* not set this, then the ftrace infrastructure will add recursion
* protection for the caller.
* STUB - The ftrace_ops is just a place holder.
+ * INITIALIZED - The ftrace_ops has already been initialized (first use time
+ * register_ftrace_function() is called, it will initialized the ops)
*/
enum {
FTRACE_OPS_FL_ENABLED = 1 << 0,
@@ -100,6 +102,7 @@ enum {
FTRACE_OPS_FL_SAVE_REGS_IF_SUPPORTED = 1 << 5,
FTRACE_OPS_FL_RECURSION_SAFE = 1 << 6,
FTRACE_OPS_FL_STUB = 1 << 7,
+ FTRACE_OPS_FL_INITIALIZED = 1 << 8,
};
struct ftrace_ops {
@@ -110,6 +113,7 @@ struct ftrace_ops {
#ifdef CONFIG_DYNAMIC_FTRACE
struct ftrace_hash *notrace_hash;
struct ftrace_hash *filter_hash;
+ struct mutex regex_lock;
#endif
};