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Subject[PATCH] modules: don't print out loaded modules too often if nothing changed
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List of loaded modules is useful but printing it at each splat
adds too much noise. This patch prints place-holder "<unchanged>"
if kernel not in panic, nothing have changed and since last print
passed less then 15 minutes. First warning will have it for sure.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
---
kernel/module.c | 13 +++++++++++++
1 file changed, 13 insertions(+)

diff --git a/kernel/module.c b/kernel/module.c
index 4d2b82e610e2..e185b8d53205 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -101,6 +101,7 @@
DEFINE_MUTEX(module_mutex);
EXPORT_SYMBOL_GPL(module_mutex);
static LIST_HEAD(modules);
+static unsigned long modules_printed;

#ifdef CONFIG_MODULES_TREE_LOOKUP

@@ -1005,6 +1006,7 @@ SYSCALL_DEFINE2(delete_module, const char __user *, name_user,

/* Store the name of the last unloaded module for diagnostic purposes */
strlcpy(last_unloaded_module, mod->name, sizeof(last_unloaded_module));
+ modules_printed = 0;

free_module(mod);
return 0;
@@ -2019,6 +2021,7 @@ static void free_module(struct module *mod)
/* Unlink carefully: kallsyms could be walking list. */
list_del_rcu(&mod->list);
mod_tree_remove(mod);
+ modules_printed = 0;
/* Remove this module from bug list, this uses list_del_rcu */
module_bug_cleanup(mod);
/* Wait for RCU-sched synchronizing before releasing mod->list and buglist. */
@@ -3343,6 +3346,7 @@ again:
mod_update_bounds(mod);
list_add_rcu(&mod->list, &modules);
mod_tree_insert(mod);
+ modules_printed = 0;
err = 0;

out:
@@ -3558,6 +3562,7 @@ static int load_module(struct load_info *info, const char __user *uargs,
/* Unlink carefully: kallsyms could be walking list. */
list_del_rcu(&mod->list);
mod_tree_remove(mod);
+ modules_printed = 0;
wake_up_all(&module_wq);
/* Wait for RCU-sched synchronizing before releasing mod->list. */
synchronize_sched();
@@ -4058,6 +4063,14 @@ void print_modules(void)
char buf[8];

printk(KERN_DEFAULT "Modules linked in:");
+
+ if (!oops_in_progress && modules_printed &&
+ time_before(jiffies, modules_printed + HZ * 60 * 15)) {
+ pr_cont(" <unchanged>\n");
+ return;
+ }
+ modules_printed = jiffies;
+
/* Most callers should already have preempt disabled, but make sure */
preempt_disable();
list_for_each_entry_rcu(mod, &modules, list) {


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