Revision 90d41e74a9c36a84e2efbd2a5b8d79299feee6fa authored by Luis R. Rodriguez on 20 July 2017, 20:13:10 UTC, committed by Greg Kroah-Hartman on 10 August 2017, 20:54:16 UTC
Fix batched requests from waiting forever on failure.
The firmware API batched requests feature has been broken since the API call
request_firmware_direct() was introduced on commit bba3a87e982ad ("firmware:
Introduce request_firmware_direct()"), added on v3.14 *iff* the firmware
being requested was not present in *certain kernel builds* [0].
When no firmware is found the worker which goes on to finish never informs
waiters queued up of this, so any batched request will stall in what seems
to be forever (MAX_SCHEDULE_TIMEOUT). Sadly, a reboot will also stall, as
the reboot notifier was only designed to kill custom fallback workers. The
issue seems to the user as a type of soft lockup, what *actually* happens
underneath the hood is a wait call which never completes as we failed to
issue a completion on error.
For device drivers with optional firmware schemes (ie, Intel iwlwifi, or
Netronome -- even though it uses request_firmware() and not
request_firmware_direct()), this could mean that when you boot a system with
multiple cards the firmware will seem to never load on the system, or that
the card is just not responsive even the driver initialization. Due to
differences in scheduling possible this should not always trigger --
one would need to to ensure that multiple requests are in place at the
right time for this to work, also release_firmware() must not be called
prior to any other incoming request. The complexity may not be worth
supporting batched requests in the future given the wait mechanism is
only used also for the fallback mechanism. We'll keep it for now and
just fix it.
Its reported that at least with the Intel WiFi cards on one system this
issue was creeping up 50% of the boots [0].
Before this commit batched requests testing revealed:
============================================================================
CONFIG_FW_LOADER_USER_HELPER_FALLBACK=n
CONFIG_FW_LOADER_USER_HELPER=y
Most common Linux distribution setup.
API-type no-firmware-found firmware-found
----------------------------------------------------------------------
request_firmware() FAIL OK
request_firmware_direct() FAIL OK
request_firmware_nowait(uevent=true) FAIL OK
request_firmware_nowait(uevent=false) FAIL OK
============================================================================
CONFIG_FW_LOADER_USER_HELPER_FALLBACK=n
CONFIG_FW_LOADER_USER_HELPER=n
Only possible if CONFIG_DELL_RBU=n and CONFIG_LEDS_LP55XX_COMMON=n, rare.
API-type no-firmware-found firmware-found
----------------------------------------------------------------------
request_firmware() FAIL OK
request_firmware_direct() FAIL OK
request_firmware_nowait(uevent=true) FAIL OK
request_firmware_nowait(uevent=false) FAIL OK
============================================================================
CONFIG_FW_LOADER_USER_HELPER_FALLBACK=y
CONFIG_FW_LOADER_USER_HELPER=y
Google Android setup.
API-type no-firmware-found firmware-found
----------------------------------------------------------------------
request_firmware() OK OK
request_firmware_direct() FAIL OK
request_firmware_nowait(uevent=true) OK OK
request_firmware_nowait(uevent=false) OK OK
============================================================================
Ater this commit batched testing results:
============================================================================
CONFIG_FW_LOADER_USER_HELPER_FALLBACK=n
CONFIG_FW_LOADER_USER_HELPER=y
Most common Linux distribution setup.
API-type no-firmware-found firmware-found
----------------------------------------------------------------------
request_firmware() OK OK
request_firmware_direct() OK OK
request_firmware_nowait(uevent=true) OK OK
request_firmware_nowait(uevent=false) OK OK
============================================================================
CONFIG_FW_LOADER_USER_HELPER_FALLBACK=n
CONFIG_FW_LOADER_USER_HELPER=n
Only possible if CONFIG_DELL_RBU=n and CONFIG_LEDS_LP55XX_COMMON=n, rare.
API-type no-firmware-found firmware-found
----------------------------------------------------------------------
request_firmware() OK OK
request_firmware_direct() OK OK
request_firmware_nowait(uevent=true) OK OK
request_firmware_nowait(uevent=false) OK OK
============================================================================
CONFIG_FW_LOADER_USER_HELPER_FALLBACK=y
CONFIG_FW_LOADER_USER_HELPER=y
Google Android setup.
API-type no-firmware-found firmware-found
----------------------------------------------------------------------
request_firmware() OK OK
request_firmware_direct() OK OK
request_firmware_nowait(uevent=true) OK OK
request_firmware_nowait(uevent=false) OK OK
============================================================================
[0] https://bugzilla.kernel.org/show_bug.cgi?id=195477
Cc: stable <stable@vger.kernel.org> # v3.14
Fixes: bba3a87e982ad ("firmware: Introduce request_firmware_direct()"
Reported-by: Nicolas <nbroeking@me.com>
Reported-by: John Ewalt <jewalt@lgsinnovations.com>
Reported-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 parent e44565f
noop-iosched.c
/*
* elevator noop
*/
#include <linux/blkdev.h>
#include <linux/elevator.h>
#include <linux/bio.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/init.h>
struct noop_data {
struct list_head queue;
};
static void noop_merged_requests(struct request_queue *q, struct request *rq,
struct request *next)
{
list_del_init(&next->queuelist);
}
static int noop_dispatch(struct request_queue *q, int force)
{
struct noop_data *nd = q->elevator->elevator_data;
struct request *rq;
rq = list_first_entry_or_null(&nd->queue, struct request, queuelist);
if (rq) {
list_del_init(&rq->queuelist);
elv_dispatch_sort(q, rq);
return 1;
}
return 0;
}
static void noop_add_request(struct request_queue *q, struct request *rq)
{
struct noop_data *nd = q->elevator->elevator_data;
list_add_tail(&rq->queuelist, &nd->queue);
}
static struct request *
noop_former_request(struct request_queue *q, struct request *rq)
{
struct noop_data *nd = q->elevator->elevator_data;
if (rq->queuelist.prev == &nd->queue)
return NULL;
return list_prev_entry(rq, queuelist);
}
static struct request *
noop_latter_request(struct request_queue *q, struct request *rq)
{
struct noop_data *nd = q->elevator->elevator_data;
if (rq->queuelist.next == &nd->queue)
return NULL;
return list_next_entry(rq, queuelist);
}
static int noop_init_queue(struct request_queue *q, struct elevator_type *e)
{
struct noop_data *nd;
struct elevator_queue *eq;
eq = elevator_alloc(q, e);
if (!eq)
return -ENOMEM;
nd = kmalloc_node(sizeof(*nd), GFP_KERNEL, q->node);
if (!nd) {
kobject_put(&eq->kobj);
return -ENOMEM;
}
eq->elevator_data = nd;
INIT_LIST_HEAD(&nd->queue);
spin_lock_irq(q->queue_lock);
q->elevator = eq;
spin_unlock_irq(q->queue_lock);
return 0;
}
static void noop_exit_queue(struct elevator_queue *e)
{
struct noop_data *nd = e->elevator_data;
BUG_ON(!list_empty(&nd->queue));
kfree(nd);
}
static struct elevator_type elevator_noop = {
.ops.sq = {
.elevator_merge_req_fn = noop_merged_requests,
.elevator_dispatch_fn = noop_dispatch,
.elevator_add_req_fn = noop_add_request,
.elevator_former_req_fn = noop_former_request,
.elevator_latter_req_fn = noop_latter_request,
.elevator_init_fn = noop_init_queue,
.elevator_exit_fn = noop_exit_queue,
},
.elevator_name = "noop",
.elevator_owner = THIS_MODULE,
};
static int __init noop_init(void)
{
return elv_register(&elevator_noop);
}
static void __exit noop_exit(void)
{
elv_unregister(&elevator_noop);
}
module_init(noop_init);
module_exit(noop_exit);
MODULE_AUTHOR("Jens Axboe");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("No-op IO scheduler");
Computing file changes ...
