diff options
Diffstat (limited to 'kernel/module/main.c')
| -rw-r--r-- | kernel/module/main.c | 133 |
1 files changed, 107 insertions, 26 deletions
diff --git a/kernel/module/main.c b/kernel/module/main.c index 044aa2c9e3cb..59b1d067e528 100644 --- a/kernel/module/main.c +++ b/kernel/module/main.c @@ -820,10 +820,8 @@ static struct module_attribute modinfo_refcnt = void __module_get(struct module *module) { if (module) { - preempt_disable(); atomic_inc(&module->refcnt); trace_module_get(module, _RET_IP_); - preempt_enable(); } } EXPORT_SYMBOL(__module_get); @@ -833,15 +831,12 @@ bool try_module_get(struct module *module) bool ret = true; if (module) { - preempt_disable(); /* Note: here, we can fail to get a reference */ if (likely(module_is_live(module) && atomic_inc_not_zero(&module->refcnt) != 0)) trace_module_get(module, _RET_IP_); else ret = false; - - preempt_enable(); } return ret; } @@ -852,11 +847,9 @@ void module_put(struct module *module) int ret; if (module) { - preempt_disable(); ret = atomic_dec_if_positive(&module->refcnt); WARN_ON(ret < 0); /* Failed to put refcount */ trace_module_put(module, _RET_IP_); - preempt_enable(); } } EXPORT_SYMBOL(module_put); @@ -1521,14 +1514,14 @@ static void __layout_sections(struct module *mod, struct load_info *info, bool i MOD_RODATA, MOD_RO_AFTER_INIT, MOD_DATA, - MOD_INVALID, /* This is needed to match the masks array */ + MOD_DATA, }; static const int init_m_to_mem_type[] = { MOD_INIT_TEXT, MOD_INIT_RODATA, MOD_INVALID, MOD_INIT_DATA, - MOD_INVALID, /* This is needed to match the masks array */ + MOD_INIT_DATA, }; for (m = 0; m < ARRAY_SIZE(masks); ++m) { @@ -3057,34 +3050,82 @@ SYSCALL_DEFINE3(init_module, void __user *, umod, return load_module(&info, uargs, 0); } -SYSCALL_DEFINE3(finit_module, int, fd, const char __user *, uargs, int, flags) +struct idempotent { + const void *cookie; + struct hlist_node entry; + struct completion complete; + int ret; +}; + +#define IDEM_HASH_BITS 8 +static struct hlist_head idem_hash[1 << IDEM_HASH_BITS]; +static DEFINE_SPINLOCK(idem_lock); + +static bool idempotent(struct idempotent *u, const void *cookie) { - struct load_info info = { }; - void *buf = NULL; - int len; - int err; + int hash = hash_ptr(cookie, IDEM_HASH_BITS); + struct hlist_head *head = idem_hash + hash; + struct idempotent *existing; + bool first; - err = may_init_module(); - if (err) - return err; + u->ret = 0; + u->cookie = cookie; + init_completion(&u->complete); - pr_debug("finit_module: fd=%d, uargs=%p, flags=%i\n", fd, uargs, flags); + spin_lock(&idem_lock); + first = true; + hlist_for_each_entry(existing, head, entry) { + if (existing->cookie != cookie) + continue; + first = false; + break; + } + hlist_add_head(&u->entry, idem_hash + hash); + spin_unlock(&idem_lock); - if (flags & ~(MODULE_INIT_IGNORE_MODVERSIONS - |MODULE_INIT_IGNORE_VERMAGIC - |MODULE_INIT_COMPRESSED_FILE)) - return -EINVAL; + return !first; +} + +/* + * We were the first one with 'cookie' on the list, and we ended + * up completing the operation. We now need to walk the list, + * remove everybody - which includes ourselves - fill in the return + * value, and then complete the operation. + */ +static int idempotent_complete(struct idempotent *u, int ret) +{ + const void *cookie = u->cookie; + int hash = hash_ptr(cookie, IDEM_HASH_BITS); + struct hlist_head *head = idem_hash + hash; + struct hlist_node *next; + struct idempotent *pos; - len = kernel_read_file_from_fd(fd, 0, &buf, INT_MAX, NULL, - READING_MODULE); + spin_lock(&idem_lock); + hlist_for_each_entry_safe(pos, next, head, entry) { + if (pos->cookie != cookie) + continue; + hlist_del(&pos->entry); + pos->ret = ret; + complete(&pos->complete); + } + spin_unlock(&idem_lock); + return ret; +} + +static int init_module_from_file(struct file *f, const char __user * uargs, int flags) +{ + struct load_info info = { }; + void *buf = NULL; + int len; + + len = kernel_read_file(f, 0, &buf, INT_MAX, NULL, READING_MODULE); if (len < 0) { mod_stat_inc(&failed_kreads); - mod_stat_add_long(len, &invalid_kread_bytes); return len; } if (flags & MODULE_INIT_COMPRESSED_FILE) { - err = module_decompress(&info, buf, len); + int err = module_decompress(&info, buf, len); vfree(buf); /* compressed data is no longer needed */ if (err) { mod_stat_inc(&failed_decompress); @@ -3099,6 +3140,46 @@ SYSCALL_DEFINE3(finit_module, int, fd, const char __user *, uargs, int, flags) return load_module(&info, uargs, flags); } +static int idempotent_init_module(struct file *f, const char __user * uargs, int flags) +{ + struct idempotent idem; + + if (!f || !(f->f_mode & FMODE_READ)) + return -EBADF; + + /* See if somebody else is doing the operation? */ + if (idempotent(&idem, file_inode(f))) { + wait_for_completion(&idem.complete); + return idem.ret; + } + + /* Otherwise, we'll do it and complete others */ + return idempotent_complete(&idem, + init_module_from_file(f, uargs, flags)); +} + +SYSCALL_DEFINE3(finit_module, int, fd, const char __user *, uargs, int, flags) +{ + int err; + struct fd f; + + err = may_init_module(); + if (err) + return err; + + pr_debug("finit_module: fd=%d, uargs=%p, flags=%i\n", fd, uargs, flags); + + if (flags & ~(MODULE_INIT_IGNORE_MODVERSIONS + |MODULE_INIT_IGNORE_VERMAGIC + |MODULE_INIT_COMPRESSED_FILE)) + return -EINVAL; + + f = fdget(fd); + err = idempotent_init_module(f.file, uargs, flags); + fdput(f); + return err; +} + /* Keep in sync with MODULE_FLAGS_BUF_SIZE !!! */ char *module_flags(struct module *mod, char *buf, bool show_state) { |