Merge tag 'modules-for-v4.13' of git://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux

Pull modules updates from Jessica Yu:
 "Summary of modules changes for the 4.13 merge window:

   - Minor code cleanups

   - Avoid accessing mod struct prior to checking module struct version,
     from Kees

   - Fix racy atomic inc/dec logic of kmod_concurrent_max in kmod, from
     Luis"

* tag 'modules-for-v4.13' of git://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux:
  module: make the modinfo name const
  kmod: reduce atomic operations on kmod_concurrent and simplify
  module: use list_for_each_entry_rcu() on find_module_all()
  kernel/module.c: suppress warning about unused nowarn variable
  module: Add module name to modinfo
  module: Pass struct load_info into symbol checks

3 files changed, 73 insertions, 53 deletions

diff --git a/kernel/kmod.c b/kernel/kmod.c
index 563f97e2be36..ff68198fe83b 100644
--- a/kernel/kmod.c
+++ b/kernel/kmod.c
@@ -45,8 +45,6 @@
 
 #include <trace/events/module.h>
 
-extern int max_threads;
-
 #define CAP_BSET        (void *)1
 #define CAP_PI          (void *)2
 
@@ -56,6 +54,20 @@ static DEFINE_SPINLOCK(umh_sysctl_lock);
 static DECLARE_RWSEM(umhelper_sem);
 
 #ifdef CONFIG_MODULES
+/*
+ * Assuming:
+ *
+ * threads = div64_u64((u64) totalram_pages * (u64) PAGE_SIZE,
+ *                     (u64) THREAD_SIZE * 8UL);
+ *
+ * If you need less than 50 threads would mean we're dealing with systems
+ * smaller than 3200 pages. This assuems you are capable of having ~13M memory,
+ * and this would only be an be an upper limit, after which the OOM killer
+ * would take effect. Systems like these are very unlikely if modules are
+ * enabled.
+ */
+#define MAX_KMOD_CONCURRENT 50
+static atomic_t kmod_concurrent_max = ATOMIC_INIT(MAX_KMOD_CONCURRENT);
 
 /*
         modprobe_path is set via /proc/sys.
@@ -127,10 +139,7 @@ int __request_module(bool wait, const char *fmt, ...)
 {
         va_list args;
         char module_name[MODULE_NAME_LEN];
-        unsigned int max_modprobes;
         int ret;
-        static atomic_t kmod_concurrent = ATOMIC_INIT(0);
-#define MAX_KMOD_CONCURRENT 50  /* Completely arbitrary value - KAO */
         static int kmod_loop_msg;
 
         /*
@@ -154,21 +163,7 @@ int __request_module(bool wait, const char *fmt, ...)
         if (ret)
                 return ret;
 
-        /* If modprobe needs a service that is in a module, we get a recursive
-         * loop.  Limit the number of running kmod threads to max_threads/2 or
-         * MAX_KMOD_CONCURRENT, whichever is the smaller.  A cleaner method
-         * would be to run the parents of this process, counting how many times
-         * kmod was invoked.  That would mean accessing the internals of the
-         * process tables to get the command line, proc_pid_cmdline is static
-         * and it is not worth changing the proc code just to handle this case. 
-         * KAO.
-         *
-         * "trace the ppid" is simple, but will fail if someone's
-         * parent exits.  I think this is as good as it gets. --RR
-         */
-        max_modprobes = min(max_threads/2, MAX_KMOD_CONCURRENT);
-        atomic_inc(&kmod_concurrent);
-        if (atomic_read(&kmod_concurrent) > max_modprobes) {
+        if (atomic_dec_if_positive(&kmod_concurrent_max) < 0) {
                 /* We may be blaming an innocent here, but unlikely */
                 if (kmod_loop_msg < 5) {
                         printk(KERN_ERR
@@ -176,7 +171,6 @@ int __request_module(bool wait, const char *fmt, ...)
                                module_name);
                         kmod_loop_msg++;
                 }
-                atomic_dec(&kmod_concurrent);
                 return -ENOMEM;
         }
 
@@ -184,10 +178,12 @@ int __request_module(bool wait, const char *fmt, ...)
 
         ret = call_modprobe(module_name, wait ? UMH_WAIT_PROC : UMH_WAIT_EXEC);
 
-        atomic_dec(&kmod_concurrent);
+        atomic_inc(&kmod_concurrent_max);
+
         return ret;
 }
 EXPORT_SYMBOL(__request_module);
+
 #endif /* CONFIG_MODULES */
 
 static void call_usermodehelper_freeinfo(struct subprocess_info *info)
diff --git a/kernel/module.c b/kernel/module.c
index b0f92a365140..40f983cbea81 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -300,6 +300,7 @@ int unregister_module_notifier(struct notifier_block *nb)
 EXPORT_SYMBOL(unregister_module_notifier);
 
 struct load_info {
+        const char *name;
         Elf_Ehdr *hdr;
         unsigned long len;
         Elf_Shdr *sechdrs;
@@ -600,7 +601,7 @@ static struct module *find_module_all(const char *name, size_t len,
 
         module_assert_mutex_or_preempt();
 
-        list_for_each_entry(mod, &modules, list) {
+        list_for_each_entry_rcu(mod, &modules, list) {
                 if (!even_unformed && mod->state == MODULE_STATE_UNFORMED)
                         continue;
                 if (strlen(mod->name) == len && !memcmp(mod->name, name, len))
@@ -1273,12 +1274,13 @@ static u32 resolve_rel_crc(const s32 *crc)
         return *(u32 *)((void *)crc + *crc);
 }
 
-static int check_version(Elf_Shdr *sechdrs,
-                         unsigned int versindex,
+static int check_version(const struct load_info *info,
                          const char *symname,
                          struct module *mod,
                          const s32 *crc)
 {
+        Elf_Shdr *sechdrs = info->sechdrs;
+        unsigned int versindex = info->index.vers;
         unsigned int i, num_versions;
         struct modversion_info *versions;
 
@@ -1312,17 +1314,16 @@ static int check_version(Elf_Shdr *sechdrs,
         }
 
         /* Broken toolchain. Warn once, then let it go.. */
-        pr_warn_once("%s: no symbol version for %s\n", mod->name, symname);
+        pr_warn_once("%s: no symbol version for %s\n", info->name, symname);
         return 1;
 
 bad_version:
         pr_warn("%s: disagrees about version of symbol %s\n",
-               mod->name, symname);
+               info->name, symname);
         return 0;
 }
 
-static inline int check_modstruct_version(Elf_Shdr *sechdrs,
-                                          unsigned int versindex,
+static inline int check_modstruct_version(const struct load_info *info,
                                           struct module *mod)
 {
         const s32 *crc;
@@ -1338,8 +1339,8 @@ static inline int check_modstruct_version(Elf_Shdr *sechdrs,
                 BUG();
         }
         preempt_enable();
-        return check_version(sechdrs, versindex,
-                             VMLINUX_SYMBOL_STR(module_layout), mod, crc);
+        return check_version(info, VMLINUX_SYMBOL_STR(module_layout),
+                             mod, crc);
 }
 
 /* First part is kernel version, which we ignore if module has crcs. */
@@ -1353,8 +1354,7 @@ static inline int same_magic(const char *amagic, const char *bmagic,
         return strcmp(amagic, bmagic) == 0;
 }
 #else
-static inline int check_version(Elf_Shdr *sechdrs,
-                                unsigned int versindex,
+static inline int check_version(const struct load_info *info,
                                 const char *symname,
                                 struct module *mod,
                                 const s32 *crc)
@@ -1362,8 +1362,7 @@ static inline int check_version(Elf_Shdr *sechdrs,
         return 1;
 }
 
-static inline int check_modstruct_version(Elf_Shdr *sechdrs,
-                                          unsigned int versindex,
+static inline int check_modstruct_version(const struct load_info *info,
                                           struct module *mod)
 {
         return 1;
@@ -1399,7 +1398,7 @@ static const struct kernel_symbol *resolve_symbol(struct module *mod,
         if (!sym)
                 goto unlock;
 
-        if (!check_version(info->sechdrs, info->index.vers, name, mod, crc)) {
+        if (!check_version(info, name, mod, crc)) {
                 sym = ERR_PTR(-EINVAL);
                 goto getname;
         }
@@ -1662,31 +1661,36 @@ static inline void remove_notes_attrs(struct module *mod)
 }
 #endif /* CONFIG_KALLSYMS */
 
-static void add_usage_links(struct module *mod)
+static void del_usage_links(struct module *mod)
 {
 #ifdef CONFIG_MODULE_UNLOAD
         struct module_use *use;
-        int nowarn;
 
         mutex_lock(&module_mutex);
-        list_for_each_entry(use, &mod->target_list, target_list) {
-                nowarn = sysfs_create_link(use->target->holders_dir,
-                                           &mod->mkobj.kobj, mod->name);
-        }
+        list_for_each_entry(use, &mod->target_list, target_list)
+                sysfs_remove_link(use->target->holders_dir, mod->name);
         mutex_unlock(&module_mutex);
 #endif
 }
 
-static void del_usage_links(struct module *mod)
+static int add_usage_links(struct module *mod)
 {
+        int ret = 0;
 #ifdef CONFIG_MODULE_UNLOAD
         struct module_use *use;
 
         mutex_lock(&module_mutex);
-        list_for_each_entry(use, &mod->target_list, target_list)
-                sysfs_remove_link(use->target->holders_dir, mod->name);
+        list_for_each_entry(use, &mod->target_list, target_list) {
+                ret = sysfs_create_link(use->target->holders_dir,
+                                        &mod->mkobj.kobj, mod->name);
+                if (ret)
+                        break;
+        }
         mutex_unlock(&module_mutex);
+        if (ret)
+                del_usage_links(mod);
 #endif
+        return ret;
 }
 
 static int module_add_modinfo_attrs(struct module *mod)
@@ -1797,13 +1801,18 @@ static int mod_sysfs_setup(struct module *mod,
         if (err)
                 goto out_unreg_param;
 
-        add_usage_links(mod);
+        err = add_usage_links(mod);
+        if (err)
+                goto out_unreg_modinfo_attrs;
+
         add_sect_attrs(mod, info);
         add_notes_attrs(mod, info);
 
         kobject_uevent(&mod->mkobj.kobj, KOBJ_ADD);
         return 0;
 
+out_unreg_modinfo_attrs:
+        module_remove_modinfo_attrs(mod);
 out_unreg_param:
         module_param_sysfs_remove(mod);
 out_unreg_holders:
@@ -2910,9 +2919,15 @@ static int rewrite_section_headers(struct load_info *info, int flags)
                 info->index.vers = 0; /* Pretend no __versions section! */
         else
                 info->index.vers = find_sec(info, "__versions");
+        info->sechdrs[info->index.vers].sh_flags &= ~(unsigned long)SHF_ALLOC;
+
         info->index.info = find_sec(info, ".modinfo");
+        if (!info->index.info)
+                info->name = "(missing .modinfo section)";
+        else
+                info->name = get_modinfo(info, "name");
         info->sechdrs[info->index.info].sh_flags &= ~(unsigned long)SHF_ALLOC;
-        info->sechdrs[info->index.vers].sh_flags &= ~(unsigned long)SHF_ALLOC;
+
         return 0;
 }
 
@@ -2952,21 +2967,29 @@ static struct module *setup_load_info(struct load_info *info, int flags)
 
         info->index.mod = find_sec(info, ".gnu.linkonce.this_module");
         if (!info->index.mod) {
-                pr_warn("No module found in object\n");
+                pr_warn("%s: No module found in object\n",
+                        info->name ?: "(missing .modinfo name field)");
                 return ERR_PTR(-ENOEXEC);
         }
         /* This is temporary: point mod into copy of data. */
         mod = (void *)info->sechdrs[info->index.mod].sh_addr;
 
+        /*
+         * If we didn't load the .modinfo 'name' field, fall back to
+         * on-disk struct mod 'name' field.
+         */
+        if (!info->name)
+                info->name = mod->name;
+
         if (info->index.sym == 0) {
-                pr_warn("%s: module has no symbols (stripped?)\n", mod->name);
+                pr_warn("%s: module has no symbols (stripped?)\n", info->name);
                 return ERR_PTR(-ENOEXEC);
         }
 
         info->index.pcpu = find_pcpusec(info);
 
         /* Check module struct version now, before we try to use module. */
-        if (!check_modstruct_version(info->sechdrs, info->index.vers, mod))
+        if (!check_modstruct_version(info, mod))
                 return ERR_PTR(-ENOEXEC);
 
         return mod;
@@ -2987,7 +3010,7 @@ static int check_modinfo(struct module *mod, struct load_info *info, int flags)
                         return err;
         } else if (!same_magic(modmagic, vermagic, info->index.vers)) {
                 pr_err("%s: version magic '%s' should be '%s'\n",
-                       mod->name, modmagic, vermagic);
+                       info->name, modmagic, vermagic);
                 return -ENOEXEC;
         }
 
@@ -3237,7 +3260,7 @@ int __weak module_frob_arch_sections(Elf_Ehdr *hdr,
 
 /* module_blacklist is a comma-separated list of module names */
 static char *module_blacklist;
-static bool blacklisted(char *module_name)
+static bool blacklisted(const char *module_name)
 {
         const char *p;
         size_t len;
@@ -3267,7 +3290,7 @@ static struct module *layout_and_allocate(struct load_info *info, int flags)
         if (IS_ERR(mod))
                 return mod;
 
-        if (blacklisted(mod->name))
+        if (blacklisted(info->name))
                 return ERR_PTR(-EPERM);
 
         err = check_modinfo(mod, info, flags);
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 30d752a4a6a6..48397feb08fb 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -2126,6 +2126,7 @@ static void add_header(struct buffer *b, struct module *mod)
         buf_printf(b, "#include <linux/compiler.h>\n");
         buf_printf(b, "\n");
         buf_printf(b, "MODULE_INFO(vermagic, VERMAGIC_STRING);\n");
+        buf_printf(b, "MODULE_INFO(name, KBUILD_MODNAME);\n");
         buf_printf(b, "\n");
         buf_printf(b, "__visible struct module __this_module\n");
         buf_printf(b, "__attribute__((section(\".gnu.linkonce.this_module\"))) = {\n");