The patch titled
modules: de-mutex more symbol lookup paths in the module code
has been added to the -mm tree. Its filename is
modules-de-mutex-more-symbol-lookup-paths-in-the-module-code.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: modules: de-mutex more symbol lookup paths in the module code
From: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Kyle McMartin reports sysrq_timer_list_show() can hit the module
mutex; 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 <rusty@xxxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Kyle McMartin <kyle@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/module.c | 29 ++++++++++++++++++-----------
1 file changed, 18 insertions(+), 11 deletions(-)
diff -puN kernel/module.c~modules-de-mutex-more-symbol-lookup-paths-in-the-module-code kernel/module.c
--- a/kernel/module.c~modules-de-mutex-more-symbol-lookup-paths-in-the-module-code
+++ a/kernel/module.c
@@ -2218,29 +2218,34 @@ static const char *get_ksymbol(struct mo
/* 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)) {
@@ -2250,12 +2255,12 @@ int lookup_module_symbol_name(unsigned l
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;
}
@@ -2264,7 +2269,7 @@ int lookup_module_symbol_attrs(unsigned
{
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)) {
@@ -2277,12 +2282,12 @@ int lookup_module_symbol_attrs(unsigned
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;
}
@@ -2291,7 +2296,7 @@ int module_get_kallsym(unsigned int symn
{
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;
@@ -2300,12 +2305,12 @@ int module_get_kallsym(unsigned int symn
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;
}
@@ -2328,6 +2333,7 @@ unsigned long module_kallsyms_lookup_nam
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)
@@ -2338,6 +2344,7 @@ unsigned long module_kallsyms_lookup_nam
if ((ret = mod_find_symname(mod, name)) != 0)
break;
}
+ preempt_enable();
return ret;
}
#endif /* CONFIG_KALLSYMS */
_
Patches currently in -mm which might be from rusty@xxxxxxxxxxxxxxx are
git-kbuild.patch
git-kvm.patch
git-libata-all.patch
git-scsi-misc.patch
kallsyms-should-prefer-non-weak-symbols.patch
virtio_net-remove-double-ether_setup.patch
modules-handle-symbols-that-have-a-zero-value.patch
modules-include-sectionsh-to-avoid-defining-linker-variables.patch
modules-fold-percpu_modcopy-into-modulec-and-get-rid-of-the-macro-from-hell.patch
modules-de-mutex-more-symbol-lookup-paths-in-the-module-code.patch
reiser4.patch
-
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