[PATCH v3 14/28] module: Use RCU in all users of __module_address().
STALE334d
LANDED: 17 (17M)
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: 2025-01-08 09:05:21
Also in:
lkml
Subsystem:
module support, the rest · Maintainers:
Luis Chamberlain, Petr Pavlu, Daniel Gomez, Sami Tolvanen, Linus Torvalds
Revision v3 of 2 in this series; 1 review trailer; landed in mainline as 6593a2c990f2 on 2025-03-10.
Revisions (2)
- v2 [diff vs current]
- v3 current
__module_address() can be invoked within a RCU section, there is no requirement to have preemption disabled. Replace the preempt_disable() section around __module_address() with RCU. Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> --- include/linux/kallsyms.h | 3 +-- kernel/module/kallsyms.c | 5 +---- kernel/module/main.c | 9 ++------- 3 files changed, 4 insertions(+), 13 deletions(-)
diff --git a/include/linux/kallsyms.h b/include/linux/kallsyms.h
index 1c6a6c1704d8d..d5dd54c53ace6 100644
--- a/include/linux/kallsyms.h
+++ b/include/linux/kallsyms.h@@ -55,12 +55,11 @@ static inline void *dereference_symbol_descriptor(void *ptr) if (is_ksym_addr((unsigned long)ptr)) return ptr; - preempt_disable(); + guard(rcu)(); mod = __module_address((unsigned long)ptr); if (mod) ptr = dereference_module_function_descriptor(mod, ptr); - preempt_enable(); #endif return ptr; }
diff --git a/kernel/module/kallsyms.c b/kernel/module/kallsyms.c
index 0e8ec6486d95c..00a60796327c0 100644
--- a/kernel/module/kallsyms.c
+++ b/kernel/module/kallsyms.c@@ -316,7 +316,7 @@ void * __weak dereference_module_function_descriptor(struct module *mod, /* * For kallsyms to ask for address resolution. NULL means not found. Careful - * not to lock to avoid deadlock on oopses, simply disable preemption. + * not to lock to avoid deadlock on oopses, RCU is enough. */ int module_address_lookup(unsigned long addr, unsigned long *size,
@@ -330,7 +330,6 @@ int module_address_lookup(unsigned long addr, struct module *mod; guard(rcu)(); - preempt_disable(); mod = __module_address(addr); if (mod) { if (modname)
@@ -348,8 +347,6 @@ int module_address_lookup(unsigned long addr, if (sym) ret = strscpy(namebuf, sym, KSYM_NAME_LEN); } - preempt_enable(); - return ret; }
diff --git a/kernel/module/main.c b/kernel/module/main.c
index 74b9e9ddb4b65..80877741ac7e5 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c@@ -3649,13 +3649,8 @@ const struct exception_table_entry *search_module_extables(unsigned long addr) */ bool is_module_address(unsigned long addr) { - bool ret; - - preempt_disable(); - ret = __module_address(addr) != NULL; - preempt_enable(); - - return ret; + guard(rcu)(); + return __module_address(addr) != NULL; } /**
--
2.47.1