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Message-Id: <20230414050836.1984746-3-mcgrof@kernel.org>
Date: Thu, 13 Apr 2023 22:08:34 -0700
From: Luis Chamberlain <mcgrof@...nel.org>
To: david@...hat.com, patches@...ts.linux.dev,
linux-modules@...r.kernel.org, linux-mm@...ck.org,
linux-kernel@...r.kernel.org, pmladek@...e.com,
petr.pavlu@...e.com, prarit@...hat.com,
torvalds@...ux-foundation.org, gregkh@...uxfoundation.org,
rafael@...nel.org
Cc: christophe.leroy@...roup.eu, tglx@...utronix.de,
peterz@...radead.org, song@...nel.org, rppt@...nel.org,
dave@...olabs.net, willy@...radead.org, vbabka@...e.cz,
mhocko@...e.com, dave.hansen@...ux.intel.com,
colin.i.king@...il.com, jim.cromie@...il.com,
catalin.marinas@....com, jbaron@...mai.com,
rick.p.edgecombe@...el.com, mcgrof@...nel.org
Subject: [PATCH v3 2/4] module: extract patient module check into helper
The patient module check inside add_unformed_module() is large
enough as we need it. It is a bit hard to read too, so just
move it to a helper and do the inverse checks first to help
shift the code and make it easier to read. The new helper then
is module_patient_check_exists().
To make this work we need to mvoe the finished_loading() up,
we do that without making any functional changes to that routine.
Reviewed-by: David Hildenbrand <david@...hat.com>
Signed-off-by: Luis Chamberlain <mcgrof@...nel.org>
---
kernel/module/main.c | 112 +++++++++++++++++++++++--------------------
1 file changed, 60 insertions(+), 52 deletions(-)
diff --git a/kernel/module/main.c b/kernel/module/main.c
index 32554d8a5791..75b23257128d 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -2447,27 +2447,6 @@ static int post_relocation(struct module *mod, const struct load_info *info)
return module_finalize(info->hdr, info->sechdrs, mod);
}
-/* Is this module of this name done loading? No locks held. */
-static bool finished_loading(const char *name)
-{
- struct module *mod;
- bool ret;
-
- /*
- * The module_mutex should not be a heavily contended lock;
- * if we get the occasional sleep here, we'll go an extra iteration
- * in the wait_event_interruptible(), which is harmless.
- */
- sched_annotate_sleep();
- mutex_lock(&module_mutex);
- mod = find_module_all(name, strlen(name), true);
- ret = !mod || mod->state == MODULE_STATE_LIVE
- || mod->state == MODULE_STATE_GOING;
- mutex_unlock(&module_mutex);
-
- return ret;
-}
-
/* Call module constructors. */
static void do_mod_ctors(struct module *mod)
{
@@ -2631,6 +2610,63 @@ static int may_init_module(void)
return 0;
}
+/* Is this module of this name done loading? No locks held. */
+static bool finished_loading(const char *name)
+{
+ struct module *mod;
+ bool ret;
+
+ /*
+ * The module_mutex should not be a heavily contended lock;
+ * if we get the occasional sleep here, we'll go an extra iteration
+ * in the wait_event_interruptible(), which is harmless.
+ */
+ sched_annotate_sleep();
+ mutex_lock(&module_mutex);
+ mod = find_module_all(name, strlen(name), true);
+ ret = !mod || mod->state == MODULE_STATE_LIVE
+ || mod->state == MODULE_STATE_GOING;
+ mutex_unlock(&module_mutex);
+
+ return ret;
+}
+
+/* Must be called with module_mutex held */
+static int module_patient_check_exists(const char *name)
+{
+ struct module *old;
+ int err = 0;
+
+ old = find_module_all(name, strlen(name), true);
+ if (old == NULL)
+ return 0;
+
+ if (old->state == MODULE_STATE_COMING ||
+ old->state == MODULE_STATE_UNFORMED) {
+ /* Wait in case it fails to load. */
+ mutex_unlock(&module_mutex);
+ err = wait_event_interruptible(module_wq,
+ finished_loading(name));
+ mutex_lock(&module_mutex);
+ if (err)
+ return err;
+
+ /* The module might have gone in the meantime. */
+ old = find_module_all(name, strlen(name), true);
+ }
+
+ /*
+ * We are here only when the same module was being loaded. Do
+ * not try to load it again right now. It prevents long delays
+ * caused by serialized module load failures. It might happen
+ * when more devices of the same type trigger load of
+ * a particular module.
+ */
+ if (old && old->state == MODULE_STATE_LIVE)
+ return -EEXIST;
+ return -EBUSY;
+}
+
/*
* We try to place it in the list now to make sure it's unique before
* we dedicate too many resources. In particular, temporary percpu
@@ -2639,41 +2675,14 @@ static int may_init_module(void)
static int add_unformed_module(struct module *mod)
{
int err;
- struct module *old;
mod->state = MODULE_STATE_UNFORMED;
mutex_lock(&module_mutex);
- old = find_module_all(mod->name, strlen(mod->name), true);
- if (old != NULL) {
- if (old->state == MODULE_STATE_COMING
- || old->state == MODULE_STATE_UNFORMED) {
- /* Wait in case it fails to load. */
- mutex_unlock(&module_mutex);
- err = wait_event_interruptible(module_wq,
- finished_loading(mod->name));
- if (err)
- goto out_unlocked;
-
- /* The module might have gone in the meantime. */
- mutex_lock(&module_mutex);
- old = find_module_all(mod->name, strlen(mod->name),
- true);
- }
-
- /*
- * We are here only when the same module was being loaded. Do
- * not try to load it again right now. It prevents long delays
- * caused by serialized module load failures. It might happen
- * when more devices of the same type trigger load of
- * a particular module.
- */
- if (old && old->state == MODULE_STATE_LIVE)
- err = -EEXIST;
- else
- err = -EBUSY;
+ err = module_patient_check_exists(mod->name);
+ if (err)
goto out;
- }
+
mod_update_bounds(mod);
list_add_rcu(&mod->list, &modules);
mod_tree_insert(mod);
@@ -2681,7 +2690,6 @@ static int add_unformed_module(struct module *mod)
out:
mutex_unlock(&module_mutex);
-out_unlocked:
return err;
}
--
2.39.2
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