firmware_class: Rework usermodehelper check
Instead of two functions, read_lock_usermodehelper() and
usermodehelper_is_disabled(), used in combination, introduce
usermodehelper_read_trylock() that will only return with umhelper_sem
held if usermodehelper_disabled is unset (and will return -EAGAIN
otherwise) and make _request_firmware() use it.
Rename read_unlock_usermodehelper() to
usermodehelper_read_unlock() to follow the naming convention of the
new function.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: stable@vger.kernel.org
diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
index 6c9387d..deee871 100644
--- a/drivers/base/firmware_class.c
+++ b/drivers/base/firmware_class.c
@@ -533,12 +533,10 @@
return 0;
}
- read_lock_usermodehelper();
-
- if (WARN_ON(usermodehelper_is_disabled())) {
+ retval = usermodehelper_read_trylock();
+ if (WARN_ON(retval)) {
dev_err(device, "firmware: %s will not be loaded\n", name);
- retval = -EBUSY;
- goto out;
+ goto out_nolock;
}
if (uevent)
@@ -573,8 +571,9 @@
fw_destroy_instance(fw_priv);
out:
- read_unlock_usermodehelper();
+ usermodehelper_read_unlock();
+out_nolock:
if (retval) {
release_firmware(firmware);
*firmware_p = NULL;
diff --git a/include/linux/kmod.h b/include/linux/kmod.h
index 9efeae6..97d22c3 100644
--- a/include/linux/kmod.h
+++ b/include/linux/kmod.h
@@ -114,8 +114,7 @@
extern int usermodehelper_disable(void);
extern void usermodehelper_enable(void);
-extern bool usermodehelper_is_disabled(void);
-extern void read_lock_usermodehelper(void);
-extern void read_unlock_usermodehelper(void);
+extern int usermodehelper_read_trylock(void);
+extern void usermodehelper_read_unlock(void);
#endif /* __LINUX_KMOD_H__ */
diff --git a/kernel/kmod.c b/kernel/kmod.c
index 957a7aa..4079ac1 100644
--- a/kernel/kmod.c
+++ b/kernel/kmod.c
@@ -339,17 +339,24 @@
*/
#define RUNNING_HELPERS_TIMEOUT (5 * HZ)
-void read_lock_usermodehelper(void)
+int usermodehelper_read_trylock(void)
{
- down_read(&umhelper_sem);
-}
-EXPORT_SYMBOL_GPL(read_lock_usermodehelper);
+ int ret = 0;
-void read_unlock_usermodehelper(void)
+ down_read(&umhelper_sem);
+ if (usermodehelper_disabled) {
+ up_read(&umhelper_sem);
+ ret = -EAGAIN;
+ }
+ return ret;
+}
+EXPORT_SYMBOL_GPL(usermodehelper_read_trylock);
+
+void usermodehelper_read_unlock(void)
{
up_read(&umhelper_sem);
}
-EXPORT_SYMBOL_GPL(read_unlock_usermodehelper);
+EXPORT_SYMBOL_GPL(usermodehelper_read_unlock);
/**
* usermodehelper_disable - prevent new helpers from being started
@@ -390,15 +397,6 @@
up_write(&umhelper_sem);
}
-/**
- * usermodehelper_is_disabled - check if new helpers are allowed to be started
- */
-bool usermodehelper_is_disabled(void)
-{
- return usermodehelper_disabled;
-}
-EXPORT_SYMBOL_GPL(usermodehelper_is_disabled);
-
static void helper_lock(void)
{
atomic_inc(&running_helpers);