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From: Christoph Hellwig <hch@lst.de>
To: Frederic Barrat <fbarrat@linux.ibm.com>,
	Andrew Donnellan <ajd@linux.ibm.com>,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	Maxime Ripard <mripard@kernel.org>,
	Thomas Zimmermann <tzimmermann@suse.de>,
	David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
	Jessica Yu <jeyu@kernel.org>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Jiri Kosina <jikos@kernel.org>, Miroslav Benes <mbenes@suse.cz>,
	Petr Mladek <pmladek@suse.com>,
	Joe Lawrence <joe.lawrence@redhat.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>,
	Michal Marek <michal.lkml@markovi.net>,
	linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
	dri-devel@lists.freedesktop.org, live-patching@vger.kernel.org,
	linux-kbuild@vger.kernel.org
Subject: [PATCH 04/13] module: use RCU to synchronize find_module
Date: Thu, 28 Jan 2021 19:14:12 +0100	[thread overview]
Message-ID: <20210128181421.2279-5-hch@lst.de> (raw)
In-Reply-To: <20210128181421.2279-1-hch@lst.de>

Allow for a RCU-sched critical section around find_module, following
the lower level find_module_all helper, and switch the two callers
outside of module.c to use such a RCU-sched critical section instead
of module_mutex.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 include/linux/module.h      | 2 +-
 kernel/livepatch/core.c     | 5 +++--
 kernel/module.c             | 1 -
 kernel/trace/trace_kprobe.c | 4 ++--
 4 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/include/linux/module.h b/include/linux/module.h
index 7a0bcb5b1ffccd..a64aa84d1b182c 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -586,7 +586,7 @@ static inline bool within_module(unsigned long addr, const struct module *mod)
 	return within_module_init(addr, mod) || within_module_core(addr, mod);
 }
 
-/* Search for module by name: must hold module_mutex. */
+/* Search for module by name: must be in a RCU-sched critical section. */
 struct module *find_module(const char *name);
 
 struct symsearch {
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index f76fdb9255323d..262cd9b003b9f0 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -19,6 +19,7 @@
 #include <linux/moduleloader.h>
 #include <linux/completion.h>
 #include <linux/memory.h>
+#include <linux/rcupdate.h>
 #include <asm/cacheflush.h>
 #include "core.h"
 #include "patch.h"
@@ -57,7 +58,7 @@ static void klp_find_object_module(struct klp_object *obj)
 	if (!klp_is_module(obj))
 		return;
 
-	mutex_lock(&module_mutex);
+	rcu_read_lock_sched();
 	/*
 	 * We do not want to block removal of patched modules and therefore
 	 * we do not take a reference here. The patches are removed by
@@ -74,7 +75,7 @@ static void klp_find_object_module(struct klp_object *obj)
 	if (mod && mod->klp_alive)
 		obj->mod = mod;
 
-	mutex_unlock(&module_mutex);
+	rcu_read_unlock_sched();
 }
 
 static bool klp_initialized(void)
diff --git a/kernel/module.c b/kernel/module.c
index 981302f616b411..6772fb2680eb3e 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -668,7 +668,6 @@ static struct module *find_module_all(const char *name, size_t len,
 
 struct module *find_module(const char *name)
 {
-	module_assert_mutex();
 	return find_module_all(name, strlen(name), false);
 }
 
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index e6fba1798771b4..3137992baa5e7a 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -124,9 +124,9 @@ static nokprobe_inline bool trace_kprobe_module_exist(struct trace_kprobe *tk)
 	if (!p)
 		return true;
 	*p = '\0';
-	mutex_lock(&module_mutex);
+	rcu_read_lock_sched();
 	ret = !!find_module(tk->symbol);
-	mutex_unlock(&module_mutex);
+	rcu_read_unlock_sched();
 	*p = ':';
 
 	return ret;
-- 
2.29.2


WARNING: multiple messages have this Message-ID
From: Christoph Hellwig <hch@lst.de>
To: Frederic Barrat <fbarrat@linux.ibm.com>,
	Andrew Donnellan <ajd@linux.ibm.com>,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	Maxime Ripard <mripard@kernel.org>,
	Thomas Zimmermann <tzimmermann@suse.de>,
	David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
	Jessica Yu <jeyu@kernel.org>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Jiri Kosina <jikos@kernel.org>, Miroslav Benes <mbenes@suse.cz>,
	Petr Mladek <pmladek@suse.com>,
	Joe Lawrence <joe.lawrence@redhat.com>
Cc: Michal Marek <michal.lkml@markovi.net>,
	linux-kbuild@vger.kernel.org,
	Masahiro Yamada <masahiroy@kernel.org>,
	linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
	live-patching@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: [PATCH 04/13] module: use RCU to synchronize find_module
Date: Thu, 28 Jan 2021 19:14:12 +0100	[thread overview]
Message-ID: <20210128181421.2279-5-hch@lst.de> (raw)
In-Reply-To: <20210128181421.2279-1-hch@lst.de>

Allow for a RCU-sched critical section around find_module, following
the lower level find_module_all helper, and switch the two callers
outside of module.c to use such a RCU-sched critical section instead
of module_mutex.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 include/linux/module.h      | 2 +-
 kernel/livepatch/core.c     | 5 +++--
 kernel/module.c             | 1 -
 kernel/trace/trace_kprobe.c | 4 ++--
 4 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/include/linux/module.h b/include/linux/module.h
index 7a0bcb5b1ffccd..a64aa84d1b182c 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -586,7 +586,7 @@ static inline bool within_module(unsigned long addr, const struct module *mod)
 	return within_module_init(addr, mod) || within_module_core(addr, mod);
 }
 
-/* Search for module by name: must hold module_mutex. */
+/* Search for module by name: must be in a RCU-sched critical section. */
 struct module *find_module(const char *name);
 
 struct symsearch {
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index f76fdb9255323d..262cd9b003b9f0 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -19,6 +19,7 @@
 #include <linux/moduleloader.h>
 #include <linux/completion.h>
 #include <linux/memory.h>
+#include <linux/rcupdate.h>
 #include <asm/cacheflush.h>
 #include "core.h"
 #include "patch.h"
@@ -57,7 +58,7 @@ static void klp_find_object_module(struct klp_object *obj)
 	if (!klp_is_module(obj))
 		return;
 
-	mutex_lock(&module_mutex);
+	rcu_read_lock_sched();
 	/*
 	 * We do not want to block removal of patched modules and therefore
 	 * we do not take a reference here. The patches are removed by
@@ -74,7 +75,7 @@ static void klp_find_object_module(struct klp_object *obj)
 	if (mod && mod->klp_alive)
 		obj->mod = mod;
 
-	mutex_unlock(&module_mutex);
+	rcu_read_unlock_sched();
 }
 
 static bool klp_initialized(void)
diff --git a/kernel/module.c b/kernel/module.c
index 981302f616b411..6772fb2680eb3e 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -668,7 +668,6 @@ static struct module *find_module_all(const char *name, size_t len,
 
 struct module *find_module(const char *name)
 {
-	module_assert_mutex();
 	return find_module_all(name, strlen(name), false);
 }
 
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index e6fba1798771b4..3137992baa5e7a 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -124,9 +124,9 @@ static nokprobe_inline bool trace_kprobe_module_exist(struct trace_kprobe *tk)
 	if (!p)
 		return true;
 	*p = '\0';
-	mutex_lock(&module_mutex);
+	rcu_read_lock_sched();
 	ret = !!find_module(tk->symbol);
-	mutex_unlock(&module_mutex);
+	rcu_read_unlock_sched();
 	*p = ':';
 
 	return ret;
-- 
2.29.2


  parent reply	other threads:[~2021-01-28 18:20 UTC|newest]

Thread overview: 61+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-28 18:14 module loader dead code removal and cleanups v2 Christoph Hellwig
2021-01-28 18:14 ` [PATCH 01/13] powerpc/powernv: remove get_cxl_module Christoph Hellwig
2021-01-28 18:14 ` [PATCH 02/13] drm: remove drm_fb_helper_modinit Christoph Hellwig
2021-02-03 10:34   ` Daniel Vetter
2021-02-03 10:49     ` Christoph Hellwig
2021-01-28 18:14 ` [PATCH 03/13] module: unexport find_module and module_mutex Christoph Hellwig
2021-01-29 15:16   ` Miroslav Benes
2021-01-28 18:14 ` Christoph Hellwig [this message]
2021-01-28 20:50   ` [PATCH 04/13] module: use RCU to synchronize find_module Thiago Jung Bauermann
2021-01-29  5:10     ` Christoph Hellwig
2021-01-29 21:29       ` Thiago Jung Bauermann
2021-01-29 10:04   ` Petr Mladek
2021-01-29 15:29   ` Miroslav Benes
2021-02-01 11:46     ` Christoph Hellwig
2021-02-01 12:10     ` Jessica Yu
2021-02-01 13:16       ` Miroslav Benes
2021-01-28 18:14 ` [PATCH 05/13] kallsyms: refactor {,module_}kallsyms_on_each_symbol Christoph Hellwig
2021-01-29  9:43   ` Petr Mladek
2021-02-01 11:47     ` Christoph Hellwig
2021-02-01 13:37       ` Miroslav Benes
2021-02-01 16:28         ` Christoph Hellwig
2021-02-02 10:45           ` Miroslav Benes
2021-02-01 14:02   ` Miroslav Benes
2021-01-28 18:14 ` [PATCH 06/13] kallsyms: only build {, module_}kallsyms_on_each_symbol when required Christoph Hellwig
2021-01-28 18:14 ` [PATCH 07/13] module: mark module_mutex static Christoph Hellwig
2021-01-28 18:14 ` [PATCH 08/13] module: remove each_symbol_in_section Christoph Hellwig
2021-01-28 18:14 ` [PATCH 09/13] module: merge each_symbol_section into find_symbol Christoph Hellwig
2021-01-28 18:14 ` [PATCH 10/13] module: pass struct find_symbol_args to find_symbol Christoph Hellwig
2021-01-28 18:14 ` [PATCH 11/13] module: move struct symsearch to module.c Christoph Hellwig
2021-01-28 18:14 ` [PATCH 12/13] module: remove EXPORT_SYMBOL_GPL_FUTURE Christoph Hellwig
2021-01-28 18:14 ` [PATCH 13/13] module: remove EXPORT_UNUSED_SYMBOL* Christoph Hellwig
2021-02-02 12:13 module loader dead code removal and cleanups v3 Christoph Hellwig
2021-02-02 12:13 ` [PATCH 04/13] module: use RCU to synchronize find_module Christoph Hellwig

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