From cb2a52052cebe4716e83b9d2e53682ba00f67de6 Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Mon, 14 Jan 2008 00:55:03 -0800 Subject: [PATCH] modules: de-mutex more symbol lookup paths in the module code Kyle McMartin reports sysrq_timer_list_show() can hit the module mutex from hard interrupt context. These paths don't need to though, since we long ago changed all the module list manipulation to occur via stop_machine(). Disabling preemption is enough. Signed-off-by: Rusty Russell Cc: Ingo Molnar Cc: Kyle McMartin Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/module.c | 29 ++++++++++++++++++----------- 1 file changed, 18 insertions(+), 11 deletions(-) diff --git a/kernel/module.c b/kernel/module.c index 91fe6958b6e1..c2e3e2e98801 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -2214,29 +2214,34 @@ static const char *get_ksymbol(struct module *mod, /* For kallsyms to ask for address resolution. NULL means not found. We don't lock, as this is used for oops resolution and races are a lesser concern. */ +/* FIXME: Risky: returns a pointer into a module w/o lock */ const char *module_address_lookup(unsigned long addr, unsigned long *size, unsigned long *offset, char **modname) { struct module *mod; + const char *ret = NULL; + preempt_disable(); list_for_each_entry(mod, &modules, list) { if (within(addr, mod->module_init, mod->init_size) || within(addr, mod->module_core, mod->core_size)) { if (modname) *modname = mod->name; - return get_ksymbol(mod, addr, size, offset); + ret = get_ksymbol(mod, addr, size, offset); + break; } } - return NULL; + preempt_enable(); + return ret; } int lookup_module_symbol_name(unsigned long addr, char *symname) { struct module *mod; - mutex_lock(&module_mutex); + preempt_disable(); list_for_each_entry(mod, &modules, list) { if (within(addr, mod->module_init, mod->init_size) || within(addr, mod->module_core, mod->core_size)) { @@ -2246,12 +2251,12 @@ int lookup_module_symbol_name(unsigned long addr, char *symname) if (!sym) goto out; strlcpy(symname, sym, KSYM_NAME_LEN); - mutex_unlock(&module_mutex); + preempt_enable(); return 0; } } out: - mutex_unlock(&module_mutex); + preempt_enable(); return -ERANGE; } @@ -2260,7 +2265,7 @@ int lookup_module_symbol_attrs(unsigned long addr, unsigned long *size, { struct module *mod; - mutex_lock(&module_mutex); + preempt_disable(); list_for_each_entry(mod, &modules, list) { if (within(addr, mod->module_init, mod->init_size) || within(addr, mod->module_core, mod->core_size)) { @@ -2273,12 +2278,12 @@ int lookup_module_symbol_attrs(unsigned long addr, unsigned long *size, strlcpy(modname, mod->name, MODULE_NAME_LEN); if (name) strlcpy(name, sym, KSYM_NAME_LEN); - mutex_unlock(&module_mutex); + preempt_enable(); return 0; } } out: - mutex_unlock(&module_mutex); + preempt_enable(); return -ERANGE; } @@ -2287,7 +2292,7 @@ int module_get_kallsym(unsigned int symnum, unsigned long *value, char *type, { struct module *mod; - mutex_lock(&module_mutex); + preempt_disable(); list_for_each_entry(mod, &modules, list) { if (symnum < mod->num_symtab) { *value = mod->symtab[symnum].st_value; @@ -2296,12 +2301,12 @@ int module_get_kallsym(unsigned int symnum, unsigned long *value, char *type, KSYM_NAME_LEN); strlcpy(module_name, mod->name, MODULE_NAME_LEN); *exported = is_exported(name, mod); - mutex_unlock(&module_mutex); + preempt_enable(); return 0; } symnum -= mod->num_symtab; } - mutex_unlock(&module_mutex); + preempt_enable(); return -ERANGE; } @@ -2324,6 +2329,7 @@ unsigned long module_kallsyms_lookup_name(const char *name) unsigned long ret = 0; /* Don't lock: we're in enough trouble already. */ + preempt_disable(); if ((colon = strchr(name, ':')) != NULL) { *colon = '\0'; if ((mod = find_module(name)) != NULL) @@ -2334,6 +2340,7 @@ unsigned long module_kallsyms_lookup_name(const char *name) if ((ret = mod_find_symname(mod, name)) != 0) break; } + preempt_enable(); return ret; } #endif /* CONFIG_KALLSYMS */ -- 2.20.1