Commit fe2e39d8 authored by Rafael J. Wysocki's avatar Rafael J. Wysocki
Browse files

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: default avatarRafael J. Wysocki <rjw@sisk.pl>
Acked-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: stable@vger.kernel.org
parent 9a4768d8

drivers/base/firmware_class.c

+5 −6
Original line number Diff line number Diff line
@@ -533,12 +533,10 @@ static int _request_firmware(const struct firmware **firmware_p, 
		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 @@ static int _request_firmware(const struct firmware **firmware_p, 
	fw_destroy_instance(fw_priv);



out:

	read_unlock_usermodehelper();

	usermodehelper_read_unlock();



out_nolock:

	if (retval) {

		release_firmware(firmware);

		*firmware_p = NULL;

include/linux/kmod.h

+2 −3
Original line number Diff line number Diff line
@@ -114,8 +114,7 @@ extern void usermodehelper_init(void); 


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__ */

kernel/kmod.c

+11 −13
Original line number Diff line number Diff line
@@ -339,17 +339,24 @@ static DECLARE_WAIT_QUEUE_HEAD(running_helpers_waitq); 
 */

#define RUNNING_HELPERS_TIMEOUT	(5 * HZ)



void read_lock_usermodehelper(void)

int usermodehelper_read_trylock(void)

{

	int ret = 0;



	down_read(&umhelper_sem);

	if (usermodehelper_disabled) {

		up_read(&umhelper_sem);

		ret = -EAGAIN;

	}

EXPORT_SYMBOL_GPL(read_lock_usermodehelper);

	return ret;

}

EXPORT_SYMBOL_GPL(usermodehelper_read_trylock);



void read_unlock_usermodehelper(void)

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 @@ void usermodehelper_enable(void) 
	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);

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