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PM: Print a warning if firmware is requested when tasks are frozen

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Some drivers erroneously use request_firmware() from their ->resume()
(or ->thaw(), or ->restore()) callbacks, which is not going to work
unless the firmware has been built in.  This causes system resume to
stall until the firmware-loading timeout expires, which makes users
think that the resume has failed and reboot their machines
unnecessarily.  For this reason, make _request_firmware() print a
warning and return immediately with error code if it has been called
when tasks are frozen and it's impossible to start any new usermode
helpers.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Reviewed-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>
This commit is contained in:
Rafael J. Wysocki 2011-05-06 20:09:42 +02:00
parent e1866b33b1
commit a144c6a6c9
3 changed files with 19 additions and 0 deletions
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5
drivers/base/firmware_class.c
View File

@ -521,6 +521,11 @@ static int _request_firmware(const struct firmware **firmware_p,
if (!firmware_p)
return -EINVAL;
if (WARN_ON(usermodehelper_is_disabled())) {
dev_err(device, "firmware: %s will not be loaded\n", name);
return -EBUSY;
}
*firmware_p = firmware = kzalloc(sizeof(*firmware), GFP_KERNEL);
if (!firmware) {
dev_err(device, "%s: kmalloc(struct firmware) failed\n",

5
include/linux/kmod.h
View File

@ -111,7 +111,12 @@ call_usermodehelper(char *path, char **argv, char **envp, enum umh_wait wait)
extern void usermodehelper_init(void);
#ifdef CONFIG_PM_SLEEP
extern int usermodehelper_disable(void);
extern void usermodehelper_enable(void);
extern bool usermodehelper_is_disabled(void);
#else
static inline bool usermodehelper_is_disabled(void) { return false; }
#endif
#endif /* __LINUX_KMOD_H__ */

9
kernel/kmod.c
View File

@ -301,6 +301,15 @@ void usermodehelper_enable(void)
usermodehelper_disabled = 0;
}
/**
* 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);