From: Luis Chamberlain <mcgrof@kernel.org>
To: david@redhat.com, patches@lists.linux.dev,
linux-modules@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, pmladek@suse.com,
petr.pavlu@suse.com, prarit@redhat.com,
torvalds@linux-foundation.org, gregkh@linuxfoundation.org,
rafael@kernel.org
Cc: christophe.leroy@csgroup.eu, tglx@linutronix.de,
peterz@infradead.org, song@kernel.org, rppt@kernel.org,
dave@stgolabs.net, willy@infradead.org, vbabka@suse.cz,
mhocko@suse.com, dave.hansen@linux.intel.com,
colin.i.king@gmail.com, jim.cromie@gmail.com,
catalin.marinas@arm.com, jbaron@akamai.com,
rick.p.edgecombe@intel.com, mcgrof@kernel.org
Subject: [PATCH v3 2/4] module: extract patient module check into helper
Date: Thu, 13 Apr 2023 22:08:34 -0700 [thread overview]
Message-ID: <20230414050836.1984746-3-mcgrof@kernel.org> (raw)
In-Reply-To: <20230414050836.1984746-1-mcgrof@kernel.org>
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@redhat.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.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
next prev parent reply other threads:[~2023-04-14 5:08 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-14 5:08 [PATCH v3 0/4] module: avoid userspace pressure on unwanted allocations Luis Chamberlain
2023-04-14 5:08 ` [PATCH v3 1/4] module: fix kmemleak annotations for non init ELF sections Luis Chamberlain
2023-04-14 10:18 ` Catalin Marinas
2023-04-14 5:08 ` Luis Chamberlain [this message]
2023-04-14 5:08 ` [PATCH v3 3/4] module: add debug stats to help identify memory pressure Luis Chamberlain
2023-04-17 11:18 ` Petr Pavlu
2023-04-18 18:30 ` Luis Chamberlain
2023-04-18 18:37 ` [PATCH v4] " Luis Chamberlain
2023-04-14 5:08 ` [PATCH v3 4/4] module: avoid allocation if module is already present and ready Luis Chamberlain
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20230414050836.1984746-3-mcgrof@kernel.org \
--to=mcgrof@kernel.org \
--cc=catalin.marinas@arm.com \
--cc=christophe.leroy@csgroup.eu \
--cc=colin.i.king@gmail.com \
--cc=dave.hansen@linux.intel.com \
--cc=dave@stgolabs.net \
--cc=david@redhat.com \
--cc=gregkh@linuxfoundation.org \
--cc=jbaron@akamai.com \
--cc=jim.cromie@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linux-modules@vger.kernel.org \
--cc=mhocko@suse.com \
--cc=patches@lists.linux.dev \
--cc=peterz@infradead.org \
--cc=petr.pavlu@suse.com \
--cc=pmladek@suse.com \
--cc=prarit@redhat.com \
--cc=rafael@kernel.org \
--cc=rick.p.edgecombe@intel.com \
--cc=rppt@kernel.org \
--cc=song@kernel.org \
--cc=tglx@linutronix.de \
--cc=torvalds@linux-foundation.org \
--cc=vbabka@suse.cz \
--cc=willy@infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).