Messages in this thread Patch in this message | | | From | "Rafael J. Wysocki" <> | Subject | [RFC][PATCH] PM: Print a warning if firmware is requested when tasks are frozen | Date | Tue, 3 May 2011 00:44:51 +0200 |
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From: Rafael J. Wysocki <rjw@sisk.pl>
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 when 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> --- drivers/base/firmware_class.c | 3 +++ include/linux/kmod.h | 1 + kernel/kmod.c | 8 ++++++++ 3 files changed, 12 insertions(+)
Index: linux-2.6/include/linux/kmod.h =================================================================== --- linux-2.6.orig/include/linux/kmod.h +++ linux-2.6/include/linux/kmod.h @@ -113,5 +113,6 @@ extern void usermodehelper_init(void); extern int usermodehelper_disable(void); extern void usermodehelper_enable(void); +extern bool usermodehelper_is_disabled(void); #endif /* __LINUX_KMOD_H__ */ Index: linux-2.6/kernel/kmod.c =================================================================== --- linux-2.6.orig/kernel/kmod.c +++ linux-2.6/kernel/kmod.c @@ -301,6 +301,14 @@ 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; +} + static void helper_lock(void) { atomic_inc(&running_helpers); Index: linux-2.6/drivers/base/firmware_class.c =================================================================== --- linux-2.6.orig/drivers/base/firmware_class.c +++ linux-2.6/drivers/base/firmware_class.c @@ -521,6 +521,9 @@ static int _request_firmware(const struc if (!firmware_p) return -EINVAL; + if (WARN_ON(usermodehelper_is_disabled())) + return -EBUSY; + *firmware_p = firmware = kzalloc(sizeof(*firmware), GFP_KERNEL); if (!firmware) { dev_err(device, "%s: kmalloc(struct firmware) failed\n",
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