5.10-stable review patch. If anyone has any objections, please let me know.
------------------
From: Christoph Hellwig <hch@xxxxxx>
[ Upstream commit a006050575745ca2be25118b90f1c37f454ac542 ]
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.
Reviewed-by: Petr Mladek <pmladek@xxxxxxxx>
Acked-by: Miroslav Benes <mbenes@xxxxxxx>
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Jessica Yu <jeyu@xxxxxxxxxx>
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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 6264617bab4d4..86fae5d1c0e39 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -582,7 +582,7 @@ 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 f5faf935c2d8f..e660ea4f90a28 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 c0e51ffe26f0a..1f9f6133c30ef 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -641,7 +641,6 @@ 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 7183572898998..5453af26ff764 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;
--
2.43.0
