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Subject[PATCH 5/5] Fix race between cat /proc/slab_allocators and rmmod
Same story as with cat /proc/*/wchan race vs rmmod race, only
/proc/slab_allocators want more info than just symbol name.
Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru>
---
include/linux/kallsyms.h | 6 ++++++
include/linux/module.h | 6 ++++++
kernel/kallsyms.c | 19 +++++++++++++++++++
kernel/module.c | 27 +++++++++++++++++++++++++++
mm/slab.c | 10 +++-------
5 files changed, 61 insertions(+), 7 deletions(-)
--- a/include/linux/kallsyms.h
+++ b/include/linux/kallsyms.h
@@ -23,6 +23,7 @@ const char *kallsyms_lookup(unsigned lon
char **modname, char *namebuf);

int lookup_symbol_name(unsigned long addr, char *symname);
+int lookup_symbol_attrs(unsigned long addr, unsigned long *size, unsigned long *offset, char *modname, char *name);

/* Replace "%s" in format with address, if found */
extern void __print_symbol(const char *fmt, unsigned long address);
@@ -54,6 +55,11 @@ static inline int lookup_symbol_name(uns
return -ERANGE;
}

+static inline int lookup_symbol_attrs(unsigned long addr, unsigned long *size, unsigned long *offset, char *modname, char *name)
+{
+ return -ERANGE;
+}
+
/* Stupid that this does nothing, but I didn't create this mess. */
#define __print_symbol(fmt, addr)
#endif /*CONFIG_KALLSYMS*/
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -457,6 +457,7 @@ const char *module_address_lookup(unsign
unsigned long *offset,
char **modname);
int lookup_module_symbol_name(unsigned long addr, char *symname);
+int lookup_module_symbol_attrs(unsigned long addr, unsigned long *size, unsigned long *offset, char *modname, char *name);

/* For extable.c to search modules' exception tables. */
const struct exception_table_entry *search_module_extables(unsigned long addr);
@@ -533,6 +534,11 @@ static inline int lookup_module_symbol_n
return -ERANGE;
}

+static inline int lookup_module_symbol_attrs(unsigned long addr, unsigned long *size, unsigned long *offset, char *modname, char *name)
+{
+ return -ERANGE;
+}
+
static inline int module_get_kallsym(unsigned int symnum, unsigned long *value,
char *type, char *name,
char *module_name, int *exported)
--- a/kernel/kallsyms.c
+++ b/kernel/kallsyms.c
@@ -286,6 +286,25 @@ int lookup_symbol_name(unsigned long add
return lookup_module_symbol_name(addr, symname);
}

+int lookup_symbol_attrs(unsigned long addr, unsigned long *size,
+ unsigned long *offset, char *modname, char *name)
+{
+ name[0] = '\0';
+ name[KSYM_NAME_LEN] = '\0';
+
+ if (is_ksym_addr(addr)) {
+ unsigned long pos;
+
+ pos = get_symbol_pos(addr, size, offset);
+ /* Grab name */
+ kallsyms_expand_symbol(get_symbol_offset(pos), name);
+ modname[0] = '\0';
+ return 0;
+ }
+ /* see if it's in a module */
+ return lookup_module_symbol_attrs(addr, size, offset, modname, name);
+}
+
/* Replace "%s" in format with address, or returns -errno. */
void __print_symbol(const char *fmt, unsigned long address)
{
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2145,6 +2145,33 @@ out:
return -ERANGE;
}

+int lookup_module_symbol_attrs(unsigned long addr, unsigned long *size,
+ unsigned long *offset, char *modname, char *name)
+{
+ struct module *mod;
+
+ mutex_lock(&module_mutex);
+ list_for_each_entry(mod, &modules, list) {
+ if (within(addr, mod->module_init, mod->init_size) ||
+ within(addr, mod->module_core, mod->core_size)) {
+ const char *sym;
+
+ sym = get_ksymbol(mod, addr, size, offset);
+ if (!sym)
+ goto out;
+ if (modname)
+ strlcpy(modname, mod->name, MODULE_NAME_LEN + 1);
+ if (name)
+ strlcpy(name, sym, KSYM_NAME_LEN + 1);
+ mutex_unlock(&module_mutex);
+ return 0;
+ }
+ }
+out:
+ mutex_unlock(&module_mutex);
+ return -ERANGE;
+}
+
int module_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
char *name, char *module_name, int *exported)
{
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -4380,16 +4380,12 @@ static void handle_slab(unsigned long *n
static void show_symbol(struct seq_file *m, unsigned long address)
{
#ifdef CONFIG_KALLSYMS
- char *modname;
- const char *name;
unsigned long offset, size;
- char namebuf[KSYM_NAME_LEN+1];
-
- name = kallsyms_lookup(address, &size, &offset, &modname, namebuf);
+ char modname[MODULE_NAME_LEN + 1], name[KSYM_NAME_LEN + 1];

- if (name) {
+ if (lookup_symbol_attrs(address, &size, &offset, modname, name) == 0) {
seq_printf(m, "%s+%#lx/%#lx", name, offset, size);
- if (modname)
+ if (modname[0])
seq_printf(m, " [%s]", modname);
return;
}
-
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