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6d0d1b5a1b
linux/drivers/tty
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Stefan Agner 6d0d1b5a1b serial: imx: fix detach/attach of serial console 
If the device used as a serial console gets detached/attached at runtime,
register_console() will try to call imx_uart_setup_console(), but this
is not possible since it is marked as __init.

For instance

  # cat /sys/devices/virtual/tty/console/active
  tty1 ttymxc0
  # echo -n N > /sys/devices/virtual/tty/console/subsystem/ttymxc0/console
  # echo -n Y > /sys/devices/virtual/tty/console/subsystem/ttymxc0/console

[   73.166649] 8<--- cut here ---
[   73.167005] Unable to handle kernel paging request at virtual address c154d928
[   73.167601] pgd = 55433e84
[   73.167875] [c154d928] *pgd=8141941e(bad)
[   73.168304] Internal error: Oops: 8000000d [#1] SMP ARM
[   73.168429] Modules linked in:
[   73.168522] CPU: 0 PID: 536 Comm: sh Not tainted 5.15.0-rc6-00056-g3968ddcf05fb #3
[   73.168675] Hardware name: Freescale i.MX6 Ultralite (Device Tree)
[   73.168791] PC is at imx_uart_console_setup+0x0/0x238
[   73.168927] LR is at try_enable_new_console+0x98/0x124
[   73.169056] pc : [<c154d928>]    lr : [<c0196f44>]    psr: a0000013
[   73.169178] sp : c2ef5e70  ip : 00000000  fp : 00000000
[   73.169281] r10: 00000000  r9 : c02cf970  r8 : 00000000
[   73.169389] r7 : 00000001  r6 : 00000001  r5 : c1760164  r4 : c1e0fb08
[   73.169512] r3 : c154d928  r2 : 00000000  r1 : efffcbd1  r0 : c1760164
[   73.169641] Flags: NzCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment none
[   73.169782] Control: 10c5387d  Table: 8345406a  DAC: 00000051
[   73.169895] Register r0 information: non-slab/vmalloc memory
[   73.170032] Register r1 information: non-slab/vmalloc memory
[   73.170158] Register r2 information: NULL pointer
[   73.170273] Register r3 information: non-slab/vmalloc memory
[   73.170397] Register r4 information: non-slab/vmalloc memory
[   73.170521] Register r5 information: non-slab/vmalloc memory
[   73.170647] Register r6 information: non-paged memory
[   73.170771] Register r7 information: non-paged memory
[   73.170892] Register r8 information: NULL pointer
[   73.171009] Register r9 information: non-slab/vmalloc memory
[   73.171142] Register r10 information: NULL pointer
[   73.171259] Register r11 information: NULL pointer
[   73.171375] Register r12 information: NULL pointer
[   73.171494] Process sh (pid: 536, stack limit = 0xcd1ba82f)
[   73.171621] Stack: (0xc2ef5e70 to 0xc2ef6000)
[   73.171731] 5e60:                                     ???????? ???????? ???????? ????????
[   73.171899] 5e80: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   73.172059] 5ea0: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   73.172217] 5ec0: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   73.172377] 5ee0: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   73.172537] 5f00: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   73.172698] 5f20: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   73.172856] 5f40: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   73.173016] 5f60: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   73.173177] 5f80: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   73.173336] 5fa0: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   73.173496] 5fc0: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   73.173654] 5fe0: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   73.173826] [<c0196f44>] (try_enable_new_console) from [<c01984a8>] (register_console+0x10c/0x2ec)
[   73.174053] [<c01984a8>] (register_console) from [<c06e2c90>] (console_store+0x14c/0x168)
[   73.174262] [<c06e2c90>] (console_store) from [<c0383718>] (kernfs_fop_write_iter+0x110/0x1cc)
[   73.174470] [<c0383718>] (kernfs_fop_write_iter) from [<c02cf5f4>] (vfs_write+0x31c/0x548)
[   73.174679] [<c02cf5f4>] (vfs_write) from [<c02cf970>] (ksys_write+0x60/0xec)
[   73.174863] [<c02cf970>] (ksys_write) from [<c0100080>] (ret_fast_syscall+0x0/0x1c)
[   73.175052] Exception stack(0xc2ef5fa8 to 0xc2ef5ff0)
[   73.175167] 5fa0:                   ???????? ???????? ???????? ???????? ???????? ????????
[   73.175327] 5fc0: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   73.175486] 5fe0: ???????? ???????? ???????? ????????
[   73.175608] Code: 00000000 00000000 00000000 00000000 (00000000)
[   73.175744] ---[ end trace 9b75121265109bf1 ]---

A similar issue could be triggered by unbinding/binding the serial
console device [*].

Drop __init so that imx_uart_setup_console() can be safely called at
runtime.

[*] https://lore.kernel.org/all/20181114174940.7865-3-stefan@agner.ch/

Fixes: a3cb39d258 ("serial: core: Allow detach and attach serial device for console")
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Francesco Dolcini <francesco.dolcini@toradex.com>
Link: https://lore.kernel.org/r/20211020192643.476895-2-francesco.dolcini@toradex.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-10-21 10:29:31 +02:00
..
hvc xen: branch for v5.15-rc5 2021-10-08 12:55:23 -07:00
ipwireless tty: drop put_tty_driver 2021-07-27 12:17:21 +02:00
serdev TTY / Serial patches for 5.15-rc1 2021-09-01 09:51:16 -07:00
serial serial: imx: fix detach/attach of serial console 2021-10-21 10:29:31 +02:00
vt TTY / Serial patches for 5.15-rc1 2021-09-01 09:51:16 -07:00
amiserial.c tty: drop put_tty_driver 2021-07-27 12:17:21 +02:00
ehv_bytechan.c tty: drop put_tty_driver 2021-07-27 12:17:21 +02:00
goldfish.c tty: drop put_tty_driver 2021-07-27 12:17:21 +02:00
Kconfig This pull request contains the following changes for UML: 2021-07-09 10:19:13 -07:00
Makefile tty: remove broken r3964 line discipline 2021-05-13 16:57:15 +02:00
mips_ejtag_fdc.c tty: drop put_tty_driver 2021-07-27 12:17:21 +02:00
moxa.c tty: moxa: merge moxa.h into moxa.c 2021-09-14 11:17:27 +02:00
mxser.c mxser: store FCR state in mxser_port::FCR 2021-10-05 14:08:09 +02:00
n_gsm.c tty: n_gsm: Don't ignore write return value in gsmld_output() 2021-10-05 14:05:59 +02:00
n_hdlc.c tty: remove file from n_tty_ioctl_helper 2021-09-22 16:59:13 +02:00
n_null.c tty: make tty_ldisc_ops a param in tty_unregister_ldisc 2021-05-13 16:57:16 +02:00
n_tty.c tty: remove file from n_tty_ioctl_helper 2021-09-22 16:59:13 +02:00
nozomi.c tty: drop put_tty_driver 2021-07-27 12:17:21 +02:00
pty.c tty: pty: correct function name pty_resize() 2021-05-20 16:33:06 +02:00
synclink_gt.c tty: synclink_gt: rename a conflicting function name 2021-09-14 10:51:37 +02:00
sysrq.c tty/sysrq: More intuitive Shift handling 2021-10-10 15:19:43 +02:00
tty_audit.c tty: audit: move some local functions out of tty.h 2021-04-15 10:24:58 +02:00
tty_baudrate.c tty: baudrate: Explicit usage of B0 for encoding input baudrate 2021-10-05 15:00:56 +02:00
tty_buffer.c tty: tty_buffer: Fix the softlockup issue in flush_to_ldisc 2021-10-18 16:53:18 +02:00
tty_io.c tty: Fix data race between tiocsti() and flush_to_ldisc() 2021-08-26 14:51:38 +02:00
tty_ioctl.c tty: remove file from n_tty_ioctl_helper 2021-09-22 16:59:13 +02:00
tty_jobctrl.c tty: tty_jobctrl: Fix 2 incorrectly documented functions 2021-05-20 17:06:15 +02:00
tty_ldisc.c tty: unexport tty_ldisc_release 2021-09-22 16:59:13 +02:00
tty_ldsem.c
tty_mutex.c tty: move some internal tty lock enums and functions out of tty.h 2021-04-15 10:26:58 +02:00
tty_port.c tty: tty_port: Fix coding style issues of block comments 2021-05-13 18:29:13 +02:00
tty.h tty: clean include/linux/tty.h up 2021-04-15 10:32:17 +02:00
ttynull.c tty: drop put_tty_driver 2021-07-27 12:17:21 +02:00
vcc.c tty: drop put_tty_driver 2021-07-27 12:17:21 +02:00