diff options
Diffstat (limited to 'kernel/kmod.c')
| -rw-r--r-- | kernel/kmod.c | 76 |
1 files changed, 43 insertions, 33 deletions
diff --git a/kernel/kmod.c b/kernel/kmod.c index d45c96073afb..6d016c5d97c8 100644 --- a/kernel/kmod.c +++ b/kernel/kmod.c @@ -20,6 +20,8 @@ */ #include <linux/module.h> #include <linux/sched.h> +#include <linux/sched/task.h> +#include <linux/binfmts.h> #include <linux/syscalls.h> #include <linux/unistd.h> #include <linux/kmod.h> @@ -43,8 +45,6 @@ #include <trace/events/module.h> -extern int max_threads; - #define CAP_BSET (void *)1 #define CAP_PI (void *)2 @@ -54,6 +54,21 @@ 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); +static DECLARE_WAIT_QUEUE_HEAD(kmod_wq); /* modprobe_path is set via /proc/sys. @@ -125,11 +140,7 @@ 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; /* * We don't allow synchronous module loading from async. Module @@ -152,40 +163,25 @@ 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) { - /* We may be blaming an innocent here, but unlikely */ - if (kmod_loop_msg < 5) { - printk(KERN_ERR - "request_module: runaway loop modprobe %s\n", - module_name); - kmod_loop_msg++; - } - atomic_dec(&kmod_concurrent); - return -ENOMEM; + if (atomic_dec_if_positive(&kmod_concurrent_max) < 0) { + pr_warn_ratelimited("request_module: kmod_concurrent_max (%u) close to 0 (max_modprobes: %u), for module %s, throttling...", + atomic_read(&kmod_concurrent_max), + MAX_KMOD_CONCURRENT, module_name); + wait_event_interruptible(kmod_wq, + atomic_dec_if_positive(&kmod_concurrent_max) >= 0); } trace_module_request(module_name, wait, _RET_IP_); ret = call_modprobe(module_name, wait ? UMH_WAIT_PROC : UMH_WAIT_EXEC); - atomic_dec(&kmod_concurrent); + atomic_inc(&kmod_concurrent_max); + wake_up(&kmod_wq); + return ret; } EXPORT_SYMBOL(__request_module); + #endif /* CONFIG_MODULES */ static void call_usermodehelper_freeinfo(struct subprocess_info *info) @@ -516,7 +512,7 @@ static void helper_unlock(void) * Function must be runnable in either a process context or the * context in which call_usermodehelper_exec is called. */ -struct subprocess_info *call_usermodehelper_setup(char *path, char **argv, +struct subprocess_info *call_usermodehelper_setup(const char *path, char **argv, char **envp, gfp_t gfp_mask, int (*init)(struct subprocess_info *info, struct cred *new), void (*cleanup)(struct subprocess_info *info), @@ -528,7 +524,12 @@ struct subprocess_info *call_usermodehelper_setup(char *path, char **argv, goto out; INIT_WORK(&sub_info->work, call_usermodehelper_exec_work); + +#ifdef CONFIG_STATIC_USERMODEHELPER + sub_info->path = CONFIG_STATIC_USERMODEHELPER_PATH; +#else sub_info->path = path; +#endif sub_info->argv = argv; sub_info->envp = envp; @@ -566,6 +567,15 @@ int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait) retval = -EBUSY; goto out; } + + /* + * If there is no binary for us to call, then just return and get out of + * here. This allows us to set STATIC_USERMODEHELPER_PATH to "" and + * disable all call_usermodehelper() calls. + */ + if (strlen(sub_info->path) == 0) + goto out; + /* * Set the completion pointer only if there is a waiter. * This makes it possible to use umh_complete to free @@ -613,7 +623,7 @@ EXPORT_SYMBOL(call_usermodehelper_exec); * This function is the equivalent to use call_usermodehelper_setup() and * call_usermodehelper_exec(). */ -int call_usermodehelper(char *path, char **argv, char **envp, int wait) +int call_usermodehelper(const char *path, char **argv, char **envp, int wait) { struct subprocess_info *info; gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL; |