path: root/kernel/module.c
diff options
authorMathieu Desnoyers <mathieu.desnoyers@efficios.com>2011-08-10 15:18:39 -0400
committerSteven Rostedt <rostedt@goodmis.org>2011-08-10 20:38:14 -0400
commitb75ef8b44b1cb95f5a26484b0e2fe37a63b12b44 (patch)
treea43affc92aaf9beea17ce8d977d8e7a7fed81c5c /kernel/module.c
parent3a301d7c1c68fd96bbcf82db82d9508918e0dc22 (diff)
Tracepoint: Dissociate from module mutex
Copy the information needed from struct module into a local module list held within tracepoint.c from within the module coming/going notifier. This vastly simplifies locking of tracepoint registration / unregistration, because we don't have to take the module mutex to register and unregister tracepoints anymore. Steven Rostedt ran into dependency problems related to modules mutex vs kprobes mutex vs ftrace mutex vs tracepoint mutex that seems to be hard to fix without removing this dependency between tracepoint and module mutex. (note: it should be investigated whether kprobes could benefit of being dissociated from the modules mutex too.) This also fixes module handling of tracepoint list iterators, because it was expecting the list to be sorted by pointer address. Given we have control on our own list now, it's OK to sort this list which has tracepoints as its only purpose. The reason why this sorting is required is to handle the fact that seq files (and any read() operation from user-space) cannot hold the tracepoint mutex across multiple calls, so list entries may vanish between calls. With sorting, the tracepoint iterator becomes usable even if the list don't contain the exact item pointed to by the iterator anymore. Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Acked-by: Jason Baron <jbaron@redhat.com> CC: Ingo Molnar <mingo@elte.hu> CC: Lai Jiangshan <laijs@cn.fujitsu.com> CC: Peter Zijlstra <a.p.zijlstra@chello.nl> CC: Thomas Gleixner <tglx@linutronix.de> CC: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Link: http://lkml.kernel.org/r/20110810191839.GC8525@Krystal Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'kernel/module.c')
1 files changed, 0 insertions, 47 deletions
diff --git a/kernel/module.c b/kernel/module.c
index 04379f92f84..93342d992f3 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -3487,50 +3487,3 @@ void module_layout(struct module *mod,
-void module_update_tracepoints(void)
- struct module *mod;
- mutex_lock(&module_mutex);
- list_for_each_entry(mod, &modules, list)
- if (!mod->taints)
- tracepoint_update_probe_range(mod->tracepoints_ptrs,
- mod->tracepoints_ptrs + mod->num_tracepoints);
- mutex_unlock(&module_mutex);
- * Returns 0 if current not found.
- * Returns 1 if current found.
- */
-int module_get_iter_tracepoints(struct tracepoint_iter *iter)
- struct module *iter_mod;
- int found = 0;
- mutex_lock(&module_mutex);
- list_for_each_entry(iter_mod, &modules, list) {
- if (!iter_mod->taints) {
- /*
- * Sorted module list
- */
- if (iter_mod < iter->module)
- continue;
- else if (iter_mod > iter->module)
- iter->tracepoint = NULL;
- found = tracepoint_get_iter_range(&iter->tracepoint,
- iter_mod->tracepoints_ptrs,
- iter_mod->tracepoints_ptrs
- + iter_mod->num_tracepoints);
- if (found) {
- iter->module = iter_mod;
- break;
- }
- }
- }
- mutex_unlock(&module_mutex);
- return found;