Re: [PATCH 5/8] module: Add module_for_each_mod() function
From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Date: 2025-02-06 05:28:21
Also in:
linux-trace-kernel, lkml
On Wed, 05 Feb 2025 17:50:36 -0500 Steven Rostedt [off-list ref] wrote:
quoted hunk ↗ jump to hunk
From: Steven Rostedt <rostedt@goodmis.org> The tracing system needs a way to save all the currently loaded modules and their addresses into persistent memory so that it can evaluate the addresses on a reboot from a crash. When the persistent memory trace starts, it will load the module addresses and names into the persistent memory. To do so, it will call the module_for_each_mod() function and pass it a function and data structure to get called on each loaded module. Then it can record the memory. This only implements that function. Cc: Luis Chamberlain <mcgrof@kernel.org> Cc: Petr Pavlu <petr.pavlu@suse.com> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Daniel Gomez <redacted> Cc: linux-modules@vger.kernel.org Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> --- include/linux/module.h | 6 ++++++ kernel/module/main.c | 14 ++++++++++++++ 2 files changed, 20 insertions(+)diff --git a/include/linux/module.h b/include/linux/module.h index 23792d5d7b74..9e1f42f03511 100644 --- a/include/linux/module.h +++ b/include/linux/module.h@@ -779,6 +779,8 @@ static inline void *module_writable_address(struct module *mod, void *loc) return __module_writable_address(mod, loc); } +void module_for_each_mod(int(*func)(struct module *mod, void *data), void *data); + #else /* !CONFIG_MODULES... */ static inline struct module *__module_address(unsigned long addr)@@ -891,6 +893,10 @@ static inline void *module_writable_address(struct module *mod, void *loc) { return loc; } + +static inline void module_for_each_mod(int(*func)(struct module *mod, void *data), void *data) +{ +} #endif /* CONFIG_MODULES */ #ifdef CONFIG_SYSFSdiff --git a/kernel/module/main.c b/kernel/module/main.c index 1fb9ad289a6f..ea1fe313fb89 100644 --- a/kernel/module/main.c +++ b/kernel/module/main.c@@ -3809,6 +3809,20 @@ bool is_module_text_address(unsigned long addr) return ret; }
It is better to add a kerneldoc for this API. /** * module_for_each_mod() - iterate all modules * @func: Callback function * @data: User data * * Call the @func with each module in the system. If @func returns !0, this * stops itrating. Note that @func must not sleep since it is called under * the preemption disabled. */ BTW, do we really need to disable preempt or is it enough to call rcu_read_lock()? Thank you,
+void module_for_each_mod(int(*func)(struct module *mod, void *data), void *data)
+{
+ struct module *mod;
+
+ preempt_disable();
+ list_for_each_entry_rcu(mod, &modules, list) {
+ if (mod->state == MODULE_STATE_UNFORMED)
+ continue;
+ if (func(mod, data))
+ break;
+ }
+ preempt_enable();
+}
+
/**
* __module_text_address() - get the module whose code contains an address.
* @addr: the address.
--
2.45.2
-- Masami Hiramatsu (Google) [off-list ref]