linux.git/drivers/rtc/class.c, branch v6.18.21

rtc: Fix offset calculation for .start_secs < 0

2025-06-01T22:10:18+00:00

The comparison

        rtc->start_secs > rtc->range_max

has a signed left-hand side and an unsigned right-hand side.
So the comparison might become true for negative start_secs which is
interpreted as a (possibly very large) positive value.

As a negative value can never be bigger than an unsigned value
the correct representation of the (mathematical) comparison

        rtc->start_secs > rtc->range_max

in C is:

        rtc->start_secs >= 0 && rtc->start_secs > rtc->range_max

Use that to fix the offset calculation currently used in the
rtc-mt6397 driver.

Fixes: 989515647e783 ("rtc: Add one offset seconds to expand RTC range")
Signed-off-by: Alexandre Mergnat 
Reviewed-by: Uwe Kleine-König 
Link: https://lore.kernel.org/r/20250428-enable-rtc-v4-2-2b2f7e3f9349@baylibre.com
Signed-off-by: Alexandre Belloni

rtc: class: Switch to use hrtimer_setup()

2025-02-18T10:19:03+00:00

hrtimer_setup() takes the callback function pointer as argument and
initializes the timer completely.

Replace hrtimer_init() and the open coded initialization of
hrtimer::function with the new setup mechanism.

Patch was created by using Coccinelle.

Signed-off-by: Nam Cao 
Signed-off-by: Thomas Gleixner 
Acked-by: Zack Rusin 
Acked-by: Alexandre Belloni 
Link: https://lore.kernel.org/all/22f3f087ddbab1708583033c07c3b7fb17810110.1738746904.git.namcao@linutronix.de

rtc: class: make rtc_class constant

2024-03-08T11:05:10+00:00

Since commit 43a7206b0963 ("driver core: class: make class_register() take
a const *"), the driver core allows for struct class to be in read-only
memory, so move the rtc_class structure to be declared at build time
placing it into read-only memory, instead of having to be dynamically
allocated at boot time.

Cc: Greg Kroah-Hartman 
Suggested-by: Greg Kroah-Hartman 
Signed-off-by: Ricardo B. Marliere 
Link: https://lore.kernel.org/r/20240305-class_cleanup-abelloni-v1-1-944c026137c8@marliere.net
Signed-off-by: Alexandre Belloni

rtc: class: Remove usage of the deprecated ida_simple_xx() API

2024-01-08T00:48:51+00:00

ida_alloc() and ida_free() should be preferred to the deprecated
ida_simple_get() and ida_simple_remove().

This is less verbose.

Signed-off-by: Christophe JAILLET 
Link: https://lore.kernel.org/r/4f2c049cb09d46fed336e22445c71988b4f340d6.1702962419.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Alexandre Belloni

driver core: class: remove module * from class_create()

2023-03-17T14:16:33+00:00

The module pointer in class_create() never actually did anything, and it
shouldn't have been requred to be set as a parameter even if it did
something.  So just remove it and fix up all callers of the function in
the kernel tree at the same time.

Cc: "Rafael J. Wysocki" 
Acked-by: Benjamin Tissoires 
Link: https://lore.kernel.org/r/20230313181843.1207845-4-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman

rtc: class: Fix potential memleak in devm_rtc_allocate_device()

2022-11-15T20:01:51+00:00

devm_rtc_allocate_device() will alloc a rtc_device first, and then run
dev_set_name(). If dev_set_name() failed, the rtc_device will memleak.
Move devm_add_action_or_reset() in front of dev_set_name() to prevent
memleak.

unreferenced object 0xffff888110a53000 (size 2048):
  comm "python3", pid 470, jiffies 4296078308 (age 58.882s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 08 30 a5 10 81 88 ff ff  .........0......
    08 30 a5 10 81 88 ff ff 00 00 00 00 00 00 00 00  .0..............
  backtrace:
    [<000000004aac0364>] kmalloc_trace+0x21/0x110
    [<000000000ff02202>] devm_rtc_allocate_device+0xd4/0x400
    [<000000001bdf5639>] devm_rtc_device_register+0x1a/0x80
    [<00000000351bf81c>] rx4581_probe+0xdd/0x110 [rtc_rx4581]
    [<00000000f0eba0ae>] spi_probe+0xde/0x130
    [<00000000bff89ee8>] really_probe+0x175/0x3f0
    [<00000000128e8d84>] __driver_probe_device+0xe6/0x170
    [<00000000ee5bf913>] device_driver_attach+0x32/0x80
    [<00000000f3f28f92>] bind_store+0x10b/0x1a0
    [<000000009ff812d8>] drv_attr_store+0x49/0x70
    [<000000008139c323>] sysfs_kf_write+0x8d/0xb0
    [<00000000b6146e01>] kernfs_fop_write_iter+0x214/0x2d0
    [<00000000ecbe3895>] vfs_write+0x61a/0x7d0
    [<00000000aa2196ea>] ksys_write+0xc8/0x190
    [<0000000046a600f5>] do_syscall_64+0x37/0x90
    [<00000000541a336f>] entry_SYSCALL_64_after_hwframe+0x63/0xcd

Fixes: 24d23181e43d ("rtc: class: check return value when calling dev_set_name()")
Signed-off-by: Shang XiaoJing 
Reviewed-by: Yang Yingliang 
Link: https://lore.kernel.org/r/20221110090810.11225-1-shangxiaojing@huawei.com
Signed-off-by: Alexandre Belloni

rtc: Directly use ida_alloc()/free()

2022-06-24T19:44:53+00:00

Use ida_alloc()/ida_free() instead of deprecated
ida_simple_get()/ida_simple_remove() .

Signed-off-by: keliu 
Signed-off-by: Alexandre Belloni 
Link: https://lore.kernel.org/r/20220527073636.2474546-1-liuke94@huawei.com

rtc: remove uie_unsupported

2022-03-23T18:58:41+00:00

uie_unsupported is not used by any drivers anymore, remove it.

Signed-off-by: Alexandre Belloni 
Link: https://lore.kernel.org/r/20220309162301.61679-29-alexandre.belloni@bootlin.com

rtc: fix use-after-free on device removal

2022-02-15T22:06:19+00:00

If the irqwork is still scheduled or running while the RTC device is
removed, a use-after-free occurs in rtc_timer_do_work().  Cleanup the
timerqueue and ensure the work is stopped to fix this.

 BUG: KASAN: use-after-free in mutex_lock+0x94/0x110
 Write of size 8 at addr ffffff801d846338 by task kworker/3:1/41

 Workqueue: events rtc_timer_do_work
 Call trace:
  mutex_lock+0x94/0x110
  rtc_timer_do_work+0xec/0x630
  process_one_work+0x5fc/0x1344
  ...

 Allocated by task 551:
  kmem_cache_alloc_trace+0x384/0x6e0
  devm_rtc_allocate_device+0xf0/0x574
  devm_rtc_device_register+0x2c/0x12c
  ...

 Freed by task 572:
  kfree+0x114/0x4d0
  rtc_device_release+0x64/0x80
  device_release+0x8c/0x1f4
  kobject_put+0x1c4/0x4b0
  put_device+0x20/0x30
  devm_rtc_release_device+0x1c/0x30
  devm_action_release+0x54/0x90
  release_nodes+0x124/0x310
  devres_release_group+0x170/0x240
  i2c_device_remove+0xd8/0x314
  ...

 Last potentially related work creation:
  insert_work+0x5c/0x330
  queue_work_on+0xcc/0x154
  rtc_set_time+0x188/0x5bc
  rtc_dev_ioctl+0x2ac/0xbd0
  ...

Signed-off-by: Vincent Whitchurch 
Signed-off-by: Alexandre Belloni 
Link: https://lore.kernel.org/r/20211210160951.7718-1-vincent.whitchurch@axis.com

rtc: expose RTC_FEATURE_UPDATE_INTERRUPT

2021-10-18T15:25:52+00:00

Set RTC_FEATURE_UPDATE_INTERRUPT by default and clear it when it is not
supported.

Signed-off-by: Alexandre Belloni 
Link: https://lore.kernel.org/r/20211018152337.78732-1-alexandre.belloni@bootlin.com