Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
Merge tag 'gpio-fixes-for-v6.14-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/brgl/linux
Pull gpio fixes from Bartosz Golaszewski:
"The first fix is a backport from my v6.15-rc1 queue that turned out to
be needed in v6.14 as well but as the former diverged from my fixes
branch I had to adjust the patch a bit.
The second one fixes a regression observed in user-space where closing
a file descriptor associated with a GPIO device results in a ~10ms
delay due to the atomic notifier calling rcu_synchronize() when
unregistering.
Summary:
- don't check the return value of gpio_chip::get_direction() when
registering a GPIO chip
- use raw notifier for line state events"
* tag 'gpio-fixes-for-v6.14-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/brgl/linux:
gpio: cdev: use raw notifier for line state events
gpiolib: don't check the retval of get_direction() when registering a chip
+29
-26
+9
-6
drivers/gpio/gpiolib-cdev.c
+9
-6
drivers/gpio/gpiolib-cdev.c
···
2729
2729
cdev->gdev = gpio_device_get(gdev);
2730
2730
2731
2731
cdev->lineinfo_changed_nb.notifier_call = lineinfo_changed_notify;
2732
-
ret = atomic_notifier_chain_register(&gdev->line_state_notifier,
2733
-
&cdev->lineinfo_changed_nb);
2732
+
scoped_guard(write_lock_irqsave, &gdev->line_state_lock)
2733
+
ret = raw_notifier_chain_register(&gdev->line_state_notifier,
2734
+
&cdev->lineinfo_changed_nb);
2734
2735
if (ret)
2735
2736
goto out_free_bitmap;
2736
2737
···
2755
2754
blocking_notifier_chain_unregister(&gdev->device_notifier,
2756
2755
&cdev->device_unregistered_nb);
2757
2756
out_unregister_line_notifier:
2758
-
atomic_notifier_chain_unregister(&gdev->line_state_notifier,
2759
-
&cdev->lineinfo_changed_nb);
2757
+
scoped_guard(write_lock_irqsave, &gdev->line_state_lock)
2758
+
raw_notifier_chain_unregister(&gdev->line_state_notifier,
2759
+
&cdev->lineinfo_changed_nb);
2760
2760
out_free_bitmap:
2761
2761
gpio_device_put(gdev);
2762
2762
bitmap_free(cdev->watched_lines);
···
2781
2779
2782
2780
blocking_notifier_chain_unregister(&gdev->device_notifier,
2783
2781
&cdev->device_unregistered_nb);
2784
-
atomic_notifier_chain_unregister(&gdev->line_state_notifier,
2785
-
&cdev->lineinfo_changed_nb);
2782
+
scoped_guard(write_lock_irqsave, &gdev->line_state_lock)
2783
+
raw_notifier_chain_unregister(&gdev->line_state_notifier,
2784
+
&cdev->lineinfo_changed_nb);
2786
2785
bitmap_free(cdev->watched_lines);
2787
2786
gpio_device_put(gdev);
2788
2787
kfree(cdev);
+16
-19
drivers/gpio/gpiolib.c
+16
-19
drivers/gpio/gpiolib.c
···
1025
1025
}
1026
1026
}
1027
1027
1028
-
ATOMIC_INIT_NOTIFIER_HEAD(&gdev->line_state_notifier);
1028
+
rwlock_init(&gdev->line_state_lock);
1029
+
RAW_INIT_NOTIFIER_HEAD(&gdev->line_state_notifier);
1029
1030
BLOCKING_INIT_NOTIFIER_HEAD(&gdev->device_notifier);
1030
1031
1031
1032
ret = init_srcu_struct(&gdev->srcu);
···
1057
1056
1058
1057
desc->gdev = gdev;
1059
1058
1060
-
if (gc->get_direction && gpiochip_line_is_valid(gc, desc_index)) {
1061
-
ret = gc->get_direction(gc, desc_index);
1062
-
if (ret < 0)
1063
-
/*
1064
-
* FIXME: Bail-out here once all GPIO drivers
1065
-
* are updated to not return errors in
1066
-
* situations that can be considered normal
1067
-
* operation.
1068
-
*/
1069
-
dev_warn(&gdev->dev,
1070
-
"%s: get_direction failed: %d\n",
1071
-
__func__, ret);
1072
-
1073
-
assign_bit(FLAG_IS_OUT, &desc->flags, !ret);
1074
-
} else {
1059
+
/*
1060
+
* We would typically want to check the return value of
1061
+
* get_direction() here but we must not check the return value
1062
+
* and bail-out as pin controllers can have pins configured to
1063
+
* alternate functions and return -EINVAL. Also: there's no
1064
+
* need to take the SRCU lock here.
1065
+
*/
1066
+
if (gc->get_direction && gpiochip_line_is_valid(gc, desc_index))
1067
+
assign_bit(FLAG_IS_OUT, &desc->flags,
1068
+
!gc->get_direction(gc, desc_index));
1069
+
else
1075
1070
assign_bit(FLAG_IS_OUT,
1076
1071
&desc->flags, !gc->direction_input);
1077
-
}
1078
1072
}
1079
1073
1080
1074
ret = of_gpiochip_add(gc);
···
4189
4193
4190
4194
void gpiod_line_state_notify(struct gpio_desc *desc, unsigned long action)
4191
4195
{
4192
-
atomic_notifier_call_chain(&desc->gdev->line_state_notifier,
4193
-
action, desc);
4196
+
guard(read_lock_irqsave)(&desc->gdev->line_state_lock);
4197
+
4198
+
raw_notifier_call_chain(&desc->gdev->line_state_notifier, action, desc);
4194
4199
}
4195
4200
4196
4201
/**
+4
-1
drivers/gpio/gpiolib.h
+4
-1
drivers/gpio/gpiolib.h
···
16
16
#include <linux/gpio/driver.h>
17
17
#include <linux/module.h>
18
18
#include <linux/notifier.h>
19
+
#include <linux/spinlock.h>
19
20
#include <linux/srcu.h>
20
21
#include <linux/workqueue.h>
21
22
···
46
45
* @list: links gpio_device:s together for traversal
47
46
* @line_state_notifier: used to notify subscribers about lines being
48
47
* requested, released or reconfigured
48
+
* @line_state_lock: RW-spinlock protecting the line state notifier
49
49
* @line_state_wq: used to emit line state events from a separate thread in
50
50
* process context
51
51
* @device_notifier: used to notify character device wait queues about the GPIO
···
74
72
const char *label;
75
73
void *data;
76
74
struct list_head list;
77
-
struct atomic_notifier_head line_state_notifier;
75
+
struct raw_notifier_head line_state_notifier;
76
+
rwlock_t line_state_lock;
78
77
struct workqueue_struct *line_state_wq;
79
78
struct blocking_notifier_head device_notifier;
80
79
struct srcu_struct srcu;