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Alexandre Belloni 10d0c768cc rtc: m41t80: fix race conditions 
The IRQ is requested before the struct rtc is allocated and registered, but
this struct is used in the IRQ handler, leading to:

Unable to handle kernel NULL pointer dereference at virtual address 0000017c
pgd = a38a2f9b
[0000017c] *pgd=00000000
Internal error: Oops: 5 [#1] ARM
Modules linked in:
CPU: 0 PID: 613 Comm: irq/48-m41t80 Not tainted 4.16.0-rc1+ #42
Hardware name: Atmel SAMA5
PC is at mutex_lock+0x14/0x38
LR is at m41t80_handle_irq+0x1c/0x9c
pc : [<c06e864c>]    lr : [<c04b70f0>]    psr: 20000013
sp : dec73f30  ip : 00000000  fp : dec56d98
r10: df437cf0  r9 : c0a03008  r8 : c0145ffc
r7 : df5c4300  r6 : dec568d0  r5 : df593000  r4 : 0000017c
r3 : df592800  r2 : 60000013  r1 : df593000  r0 : 0000017c
Flags: nzCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment none
Control: 10c53c7d  Table: 20004059  DAC: 00000051
Process irq/48-m41t80 (pid: 613, stack limit = 0xb52d091e)
Stack: (0xdec73f30 to 0xdec74000)
3f20:                                     dec56840 df5c4300 00000001 df5c4300
3f40: c0145ffc c0146018 dec56840 ffffe000 00000001 c0146290 dec567c0 00000000
3f60: c0146084 ed7c9a62 c014615c dec56d80 dec567c0 00000000 dec72000 dec56840
3f80: c014615c c012ffc0 dec72000 dec567c0 c012fe80 00000000 00000000 00000000
3fa0: 00000000 00000000 00000000 c01010e8 00000000 00000000 00000000 00000000
3fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
3fe0: 00000000 00000000 00000000 00000000 00000013 00000000 29282726 2d2c2b2a
[<c06e864c>] (mutex_lock) from [<c04b70f0>] (m41t80_handle_irq+0x1c/0x9c)
[<c04b70f0>] (m41t80_handle_irq) from [<c0146018>] (irq_thread_fn+0x1c/0x54)
[<c0146018>] (irq_thread_fn) from [<c0146290>] (irq_thread+0x134/0x1c0)
[<c0146290>] (irq_thread) from [<c012ffc0>] (kthread+0x140/0x148)
[<c012ffc0>] (kthread) from [<c01010e8>] (ret_from_fork+0x14/0x2c)
Exception stack(0xdec73fb0 to 0xdec73ff8)
3fa0:                                     00000000 00000000 00000000 00000000
3fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
3fe0: 00000000 00000000 00000000 00000000 00000013 00000000
Code: e3c33d7f e3c3303f f5d0f000 e593300c (e1901f9f)
---[ end trace 22b027302eb7c604 ]---
genirq: exiting task "irq/48-m41t80" (613) is an active IRQ thread (irq 48)

Also, there is another possible race condition. The probe function is not
allowed to fail after the RTC is registered because the following may
happen:

CPU0:                                CPU1:
sys_load_module()
 do_init_module()
  do_one_initcall()
   cmos_do_probe()
    rtc_device_register()
     __register_chrdev()
     cdev->owner = struct module*
                                     open("/dev/rtc0")
    rtc_device_unregister()
  module_put()
  free_module()
   module_free(mod->module_core)
   /* struct module *module is now
      freed */
                                      chrdev_open()
                                       spin_lock(cdev_lock)
                                       cdev_get()
                                        try_module_get()
                                         module_is_live()
                                         /* dereferences already
                                            freed struct module* */

Switch to devm_rtc_allocate_device/rtc_register_device to allocate the rtc
before requesting the IRQ and register it as late as possible.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
 		2018-03-17 14:20:48 +01:00
..
accessibility
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acpi vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
amba
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android vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
ata pci-v4.16-changes 2018-02-06 09:59:40 -08:00
atm atm: he: use 64-bit arithmetic instead of 32-bit 2018-02-08 15:05:16 -05:00
auxdisplay
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base More power management updates for v4.16-rc1 2018-02-09 09:40:33 -08:00
bcma Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-01-19 22:59:33 -05:00
block Things have been very quiet on the rbd side, as work continues on the 2018-02-08 11:38:59 -08:00
bluetooth vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
bus ARM: SoC driver updates for 4.16 2018-02-01 16:35:31 -08:00
cdrom
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char char: rtc: remove unused rtc_control() API 2018-03-01 10:49:37 +01:00
clk MIPS changes for 4.16 2018-02-07 11:22:44 -08:00
clocksource
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connector
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cpufreq arm: imx: Add MODULE_ALIAS for cpufreq 2018-02-08 10:21:39 +01:00
cpuidle powerpc updates for 4.16 2018-02-02 10:01:04 -08:00
crypto KVM changes for 4.16 2018-02-10 13:16:35 -08:00
dax Merge branch 'for-4.16/dax' into libnvdimm-for-next 2018-02-03 00:26:10 -07:00
dca
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devfreq
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dio
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dma Merge branch 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm 2018-02-02 09:50:51 -08:00
dma-buf vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
edac
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eisa EISA: Delete error message for a failed memory allocation in eisa_probe() 2018-01-23 09:04:10 +01:00
extcon
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firewire vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
firmware 2nd set of arm64 updates for 4.16: 2018-02-08 10:44:25 -08:00
fmc
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fpga
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fsi
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gpio vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
gpu vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
hid vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
hsi vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
hv vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
hwmon hwmon: (dell-smm) Disable fan support for Dell Vostro 3360 2018-01-27 09:34:22 -08:00
hwspinlock
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hwtracing Char/Misc driver patches for 4.16-rc1 2018-02-01 10:31:17 -08:00
i2c Merge branch 'i2c/for-4.16' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux 2018-02-04 10:57:43 -08:00
ide pci-v4.16-changes 2018-02-06 09:59:40 -08:00
idle
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iio vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
infiniband vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
input vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
iommu IOMMU Updates for Linux v4.16 2018-02-08 12:03:54 -08:00
ipack
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irqchip pci-v4.16-changes 2018-02-06 09:59:40 -08:00
isdn vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
leds vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
lightnvm
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macintosh vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
mailbox vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
mcb
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md vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
media vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
memory ARM: SoC driver updates for 4.16 2018-02-01 16:35:31 -08:00
memstick
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message
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mfd vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
misc vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
mmc Kbuild updates for v4.16 (2nd) 2018-02-09 19:32:41 -08:00
mtd dma mapping changes for Linux 4.16: 2018-01-31 11:32:27 -08:00
mux Char/Misc driver patches for 4.16-rc1 2018-02-01 10:31:17 -08:00
net vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
nfc
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ntb NTB: ntb_perf: fix cast to restricted __le32 2018-01-28 22:17:24 -05:00
nubus
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nvdimm Merge branch 'for-4.16/nfit' into libnvdimm-for-next 2018-02-03 00:26:26 -07:00
nvme for-linus-20180204 2018-02-04 11:16:35 -08:00
nvmem
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of pci-v4.16-changes 2018-02-06 09:59:40 -08:00
opp
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oprofile
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parisc
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parport
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pci vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
pcmcia Merge branch 'pcmcia' of git://git.kernel.org/pub/scm/linux/kernel/git/brodo/pcmcia 2018-02-08 11:48:49 -08:00
perf bitmap: replace bitmap_{from,to}_u32array 2018-02-06 18:32:44 -08:00
phy USB/PHY updates for 4.16-rc1 2018-02-01 09:40:49 -08:00
pinctrl This is the bulk of pin control changes for the v4.16 kernel cycle: 2018-02-02 14:22:53 -08:00
platform vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
pnp
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power power supply and reset changes for the v4.16 series 2018-01-31 12:55:31 -08:00
powercap
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pps vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
ps3
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ptp vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
pwm
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rapidio vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
ras mm/memory_failure: Remove unused trapno from memory_failure 2018-01-23 12:17:42 -06:00
regulator regulator: Fix suspend to idle 2018-01-30 12:25:59 +00:00
remoteproc remoteproc updates for v4.16 2018-02-05 10:07:40 -08:00
reset
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rpmsg vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
rtc rtc: m41t80: fix race conditions 2018-03-17 14:20:48 +01:00
s390 vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
sbus pci-v4.16-changes 2018-02-06 09:59:40 -08:00
scsi vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
sfi
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sh cpufreq: Add and use cpufreq_for_each_{valid_,}entry_idx() 2018-02-08 10:21:39 +01:00
siox
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slimbus
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sn
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soc ARM: SoC driver updates for 4.16 2018-02-01 16:35:31 -08:00
soundwire soundwire: Fix a signedness bug 2018-01-22 16:45:26 +01:00
spi Merge remote-tracking branch 'spi/topic/xilinx' into spi-next 2018-01-26 17:57:34 +00:00
spmi
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ssb Merge git://git.kernel.org/pub/scm/linux/kernel/git/kvalo/wireless-drivers.git 2018-02-01 10:37:39 +02:00
staging vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
target Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending 2018-02-09 14:49:46 -08:00
tc
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tee
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thermal Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/rzhang/linux 2018-02-06 15:04:58 -08:00
thunderbolt
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tty vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
uio vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
usb vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
uwb
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vfio vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
vhost vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
video Kbuild updates for v4.16 (2nd) 2018-02-09 19:32:41 -08:00
virt vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
virtio virtio_pci: don't kfree device on register failure 2018-02-01 16:26:45 +02:00
visorbus
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vlynq
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vme
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w1 Documentation updates for 4.16. New stuff includes refcount_t 2018-01-31 19:25:25 -08:00
watchdog linux-watchdog 4.16-rc1 merge window tag 2018-02-07 11:54:34 -08:00
xen vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
zorro
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Kconfig Char/Misc driver patches for 4.16-rc1 2018-02-01 10:31:17 -08:00
Makefile pci-v4.16-changes 2018-02-06 09:59:40 -08:00