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firmware_class: Rework usermodehelper check

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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
This commit is contained in:
Rafael J. Wysocki 2012-03-28 23:29:45 +02:00
parent 9a4768d849
commit fe2e39d878
3 changed files with 20 additions and 24 deletions
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11
drivers/base/firmware_class.c
View file

@ -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;

5
include/linux/kmod.h
View file

@ -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__ */

28
kernel/kmod.c
View file

@ -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)
{
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 @@ 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);