linux/drivers/base/firmware_class.c, branch v3.4-rc2

firmware_class: Move request_firmware_nowait() to workqueues

2012-03-28T21:31:00Z

Oddly enough a work_struct was already part of the firmware_work structure but nobody was using it. Instead of creating a new kthread for each request_firmware_nowait() call just schedule the work on the system workqueue. This should avoid some overhead in forking new threads when they're not strictly necessary. Signed-off-by: Stephen Boyd Acked-by: Greg Kroah-Hartman Signed-off-by: Rafael J. Wysocki

firmware_class: Reorganize fw_create_instance()

2012-03-28T21:30:43Z

Recent patches to split up the three phases of request_firmware() lead to a casting away of const in fw_create_instance(). We can avoid this cast by splitting up fw_create_instance() a bit. Make _request_firmware_setup() return a struct fw_priv and use that struct instead of passing struct firmware to _request_firmware(). Move the uevent and device file creation bits to the loading phase and rename the function to _request_firmware_load() to better reflect its purpose. Signed-off-by: Stephen Boyd Acked-by: Greg Kroah-Hartman Signed-off-by: Rafael J. Wysocki

firmware_class: Do not warn that system is not ready from async loads

2012-03-28T21:30:02Z

If firmware is requested asynchronously, by calling request_firmware_nowait(), there is no reason to fail the request (and warn the user) when the system is (presumably temporarily) unready to handle it (because user space is not available yet or frozen). For this reason, introduce an alternative routine for read-locking umhelper_sem, usermodehelper_read_lock_wait(), that will wait for usermodehelper_disabled to be unset (possibly with a timeout) and make request_firmware_work_func() use it instead of usermodehelper_read_trylock(). Accordingly, modify request_firmware() so that it uses usermodehelper_read_trylock() to acquire umhelper_sem and remove the code related to that lock from _request_firmware(). Signed-off-by: Rafael J. Wysocki Acked-by: Greg Kroah-Hartman Cc: stable@vger.kernel.org

firmware_class: Split _request_firmware() into three functions, v2

2012-03-28T21:29:55Z

Split _request_firmware() into three functions, _request_firmware_prepare() doing preparatory work that need not be done under umhelper_sem, _request_firmware_cleanup() doing the post-error cleanup and _request_firmware() carrying out the remaining operations. This change is requisite for moving the acquisition of umhelper_sem from _request_firmware() to the callers, which is going to be done subsequently. Signed-off-by: Rafael J. Wysocki Acked-by: Greg Kroah-Hartman Reviewed-by: Stephen Boyd Cc: stable@vger.kernel.org

firmware_class: Rework usermodehelper check

2012-03-28T21:29:45Z

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 Acked-by: Greg Kroah-Hartman Cc: stable@vger.kernel.org

PM / Sleep: Fix read_unlock_usermodehelper() call.

2012-01-23T20:59:08Z

Commit b298d289 "PM / Sleep: Fix freezer failures due to racy usermodehelper_is_disabled()" added read_unlock_usermodehelper() but read_unlock_usermodehelper() is called without read_lock_usermodehelper() when kmalloc() failed. Signed-off-by: Tetsuo Handa Acked-by: Srivatsa S. Bhat Signed-off-by: Rafael J. Wysocki

Merge branch 'pm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

2012-01-08T21:10:57Z

* 'pm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (76 commits) PM / Hibernate: Implement compat_ioctl for /dev/snapshot PM / Freezer: fix return value of freezable_schedule_timeout_killable() PM / shmobile: Allow the A4R domain to be turned off at run time PM / input / touchscreen: Make st1232 use device PM QoS constraints PM / QoS: Introduce dev_pm_qos_add_ancestor_request() PM / shmobile: Remove the stay_on flag from SH7372's PM domains PM / shmobile: Don't include SH7372's INTCS in syscore suspend/resume PM / shmobile: Add support for the sh7372 A4S power domain / sleep mode PM: Drop generic_subsys_pm_ops PM / Sleep: Remove forward-only callbacks from AMBA bus type PM / Sleep: Remove forward-only callbacks from platform bus type PM: Run the driver callback directly if the subsystem one is not there PM / Sleep: Make pm_op() and pm_noirq_op() return callback pointers PM/Devfreq: Add Exynos4-bus device DVFS driver for Exynos4210/4212/4412. PM / Sleep: Merge internal functions in generic_ops.c PM / Sleep: Simplify generic system suspend callbacks PM / Hibernate: Remove deprecated hibernation snapshot ioctls PM / Sleep: Fix freezer failures due to racy usermodehelper_is_disabled() ARM: S3C64XX: Implement basic power domain support PM / shmobile: Use common always on power domain governor ... Fix up trivial conflict in fs/xfs/xfs_buf.c due to removal of unused XBT_FORCE_SLEEP bit

firmware: Fix an oops on reading fw_priv->fw in sysfs loading file

2012-01-05T00:31:29Z

This oops was reported recently: firmware_loading_store+0xf9/0x17b dev_attr_store+0x20/0x22 sysfs_write_file+0x101/0x134 vfs_write+0xac/0xf3 sys_write+0x4a/0x6e system_call_fastpath+0x16/0x1b The complete backtrace was unfortunately not captured, but details can be found here: https://bugzilla.redhat.com/show_bug.cgi?id=769920 The cause is fairly clear. Its caused by the fact that firmware_loading_store has a case 0 in its switch statement that reads and writes the fw_priv->fw poniter without the protection of the fw_lock mutex. since there is a window between the time that _request_firmware sets fw_priv->fw to NULL and the time the corresponding sysfs file is unregistered, its possible for a user space application to race in, and write a zero to the loading file, causing a NULL dereference in firmware_loading_store. Fix it by extending the protection of the fw_lock mutex to cover all of the firware_loading_store function. Signed-off-by: Neil Horman Cc: stable Signed-off-by: Greg Kroah-Hartman

PM / Sleep: Fix freezer failures due to racy usermodehelper_is_disabled()

2011-12-09T22:36:36Z

Commit a144c6a (PM: Print a warning if firmware is requested when tasks are frozen) introduced usermodehelper_is_disabled() to warn and exit immediately if firmware is requested when usermodehelpers are disabled. However, it is racy. Consider the following scenario, currently used in drivers/base/firmware_class.c: ... if (usermodehelper_is_disabled()) goto out; /* Do actual work */ ... out: return err; Nothing prevents someone from disabling usermodehelpers just after the check in the 'if' condition, which means that it is quite possible to try doing the "actual work" with usermodehelpers disabled, leading to undesirable consequences. In particular, this race condition in _request_firmware() causes task freezing failures whenever suspend/hibernation is in progress because, it wrongly waits to get the firmware/microcode image from userspace when actually the usermodehelpers are disabled or userspace has been frozen. Some of the example scenarios that cause freezing failures due to this race are those that depend on userspace via request_firmware(), such as x86 microcode module initialization and microcode image reload. Previous discussions about this issue can be found at: http://thread.gmane.org/gmane.linux.kernel/1198291/focus=1200591 This patch adds proper synchronization to fix this issue. It is to be noted that this patchset fixes the freezing failures but doesn't remove the warnings. IOW, it does not attempt to add explicit synchronization to x86 microcode driver to avoid requesting microcode image at inopportune moments. Because, the warnings were introduced to highlight such cases, in the first place. And we need not silence the warnings, since we take care of the *real* problem (freezing failure) and hence, after that, the warnings are pretty harmless anyway. Signed-off-by: Srivatsa S. Bhat Signed-off-by: Rafael J. Wysocki

firmware loader: allow builtin firmware load even if usermodehelper is disabled

2011-08-24T22:55:30Z

In commit a144c6a6c924 ("PM: Print a warning if firmware is requested when tasks are frozen") we not only printed a warning if somebody tried to load the firmware when tasks are frozen - we also failed the load. But that check was done before the check for built-in firmware, and then when we disallowed usermode helpers during bootup (commit 288d5abec831: "Boot up with usermodehelper disabled"), that actually means that built-in modules can no longer load their firmware even if the firmware is built in too. Which used to work, and some people depended on it for the R100 driver. So move the test for usermodehelper_is_disabled() down, to after checking the built-in firmware. This should fix: https://bugzilla.kernel.org/show_bug.cgi?id=40952 Reported-by: James Cloos Bisected-by: Elimar Riesebieter Cc: Michel Dänzer Cc: Rafael Wysocki Cc: Greg Kroah-Hartman Cc: Valdis Kletnieks Signed-off-by: Linus Torvalds