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-rw-r--r--kernel/kmod.c27
1 files changed, 24 insertions, 3 deletions
diff --git a/kernel/kmod.c b/kernel/kmod.c
index a4bea97c75b6..a0a88543934e 100644
--- a/kernel/kmod.c
+++ b/kernel/kmod.c
@@ -36,6 +36,7 @@
36#include <linux/resource.h> 36#include <linux/resource.h>
37#include <linux/notifier.h> 37#include <linux/notifier.h>
38#include <linux/suspend.h> 38#include <linux/suspend.h>
39#include <linux/rwsem.h>
39#include <asm/uaccess.h> 40#include <asm/uaccess.h>
40 41
41#include <trace/events/module.h> 42#include <trace/events/module.h>
@@ -50,6 +51,7 @@ static struct workqueue_struct *khelper_wq;
50static kernel_cap_t usermodehelper_bset = CAP_FULL_SET; 51static kernel_cap_t usermodehelper_bset = CAP_FULL_SET;
51static kernel_cap_t usermodehelper_inheritable = CAP_FULL_SET; 52static kernel_cap_t usermodehelper_inheritable = CAP_FULL_SET;
52static DEFINE_SPINLOCK(umh_sysctl_lock); 53static DEFINE_SPINLOCK(umh_sysctl_lock);
54static DECLARE_RWSEM(umhelper_sem);
53 55
54#ifdef CONFIG_MODULES 56#ifdef CONFIG_MODULES
55 57
@@ -275,6 +277,7 @@ static void __call_usermodehelper(struct work_struct *work)
275 * If set, call_usermodehelper_exec() will exit immediately returning -EBUSY 277 * If set, call_usermodehelper_exec() will exit immediately returning -EBUSY
276 * (used for preventing user land processes from being created after the user 278 * (used for preventing user land processes from being created after the user
277 * land has been frozen during a system-wide hibernation or suspend operation). 279 * land has been frozen during a system-wide hibernation or suspend operation).
280 * Should always be manipulated under umhelper_sem acquired for write.
278 */ 281 */
279static int usermodehelper_disabled = 1; 282static int usermodehelper_disabled = 1;
280 283
@@ -282,17 +285,29 @@ static int usermodehelper_disabled = 1;
282static atomic_t running_helpers = ATOMIC_INIT(0); 285static atomic_t running_helpers = ATOMIC_INIT(0);
283 286
284/* 287/*
285 * Wait queue head used by usermodehelper_pm_callback() to wait for all running 288 * Wait queue head used by usermodehelper_disable() to wait for all running
286 * helpers to finish. 289 * helpers to finish.
287 */ 290 */
288static DECLARE_WAIT_QUEUE_HEAD(running_helpers_waitq); 291static DECLARE_WAIT_QUEUE_HEAD(running_helpers_waitq);
289 292
290/* 293/*
291 * Time to wait for running_helpers to become zero before the setting of 294 * Time to wait for running_helpers to become zero before the setting of
292 * usermodehelper_disabled in usermodehelper_pm_callback() fails 295 * usermodehelper_disabled in usermodehelper_disable() fails
293 */ 296 */
294#define RUNNING_HELPERS_TIMEOUT (5 * HZ) 297#define RUNNING_HELPERS_TIMEOUT (5 * HZ)
295 298
299void read_lock_usermodehelper(void)
300{
301 down_read(&umhelper_sem);
302}
303EXPORT_SYMBOL_GPL(read_lock_usermodehelper);
304
305void read_unlock_usermodehelper(void)
306{
307 up_read(&umhelper_sem);
308}
309EXPORT_SYMBOL_GPL(read_unlock_usermodehelper);
310
296/** 311/**
297 * usermodehelper_disable - prevent new helpers from being started 312 * usermodehelper_disable - prevent new helpers from being started
298 */ 313 */
@@ -300,8 +315,10 @@ int usermodehelper_disable(void)
300{ 315{
301 long retval; 316 long retval;
302 317
318 down_write(&umhelper_sem);
303 usermodehelper_disabled = 1; 319 usermodehelper_disabled = 1;
304 smp_mb(); 320 up_write(&umhelper_sem);
321
305 /* 322 /*
306 * From now on call_usermodehelper_exec() won't start any new 323 * From now on call_usermodehelper_exec() won't start any new
307 * helpers, so it is sufficient if running_helpers turns out to 324 * helpers, so it is sufficient if running_helpers turns out to
@@ -314,7 +331,9 @@ int usermodehelper_disable(void)
314 if (retval) 331 if (retval)
315 return 0; 332 return 0;
316 333
334 down_write(&umhelper_sem);
317 usermodehelper_disabled = 0; 335 usermodehelper_disabled = 0;
336 up_write(&umhelper_sem);
318 return -EAGAIN; 337 return -EAGAIN;
319} 338}
320 339
@@ -323,7 +342,9 @@ int usermodehelper_disable(void)
323 */ 342 */
324void usermodehelper_enable(void) 343void usermodehelper_enable(void)
325{ 344{
345 down_write(&umhelper_sem);
326 usermodehelper_disabled = 0; 346 usermodehelper_disabled = 0;
347 up_write(&umhelper_sem);
327} 348}
328 349
329/** 350/**