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141822aa3f
If driver probe needs to be deferred, e.g. because ci_hdrc_add_device()
isn't ready yet, this driver currently misbehaves badly:
a) success is still reported to the driver core (meaning a 2nd
probe attempt will never be done), leaving the driver in
a dysfunctional state and the hardware unusable
b) driver remove / shutdown OOPSes:
[ 206.786916] Unable to handle kernel paging request at virtual address fffffdff
[ 206.794148] pgd = 880b9f82
[ 206.796890] [fffffdff] *pgd=abf5e861, *pte=00000000, *ppte=00000000
[ 206.803179] Internal error: Oops: 37 [#1] PREEMPT SMP ARM
[ 206.808581] Modules linked in: wl18xx evbug
[ 206.813308] CPU: 1 PID: 1 Comm: systemd-shutdow Not tainted 4.19.35+gf345c93b4195 #1
[ 206.821053] Hardware name: Freescale i.MX7 Dual (Device Tree)
[ 206.826813] PC is at ci_hdrc_remove_device+0x4/0x20
[ 206.831699] LR is at ci_hdrc_imx_remove+0x20/0xe8
[ 206.836407] pc : [<805cd4b0>] lr : [<805d62cc>] psr: 20000013
[ 206.842678] sp : a806be40 ip : 00000001 fp : 80adbd3c
[ 206.847906] r10: 80b1b794 r9 : 80d5dfe0 r8 : a8192c44
[ 206.853136] r7 : 80db93a0 r6 : a8192c10 r5 : a8192c00 r4 : a93a4a00
[ 206.859668] r3 : 00000000 r2 : a8192ce4 r1 : ffffffff r0 : fffffdfb
[ 206.866201] Flags: nzCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none
[ 206.873341] Control: 10c5387d Table: a9e0c06a DAC: 00000051
[ 206.879092] Process systemd-shutdow (pid: 1, stack limit = 0xb271353c)
[ 206.885624] Stack: (0xa806be40 to 0xa806c000)
[ 206.889992] be40: a93a4a00 805d62cc a8192c1c a8170e10 a8192c10 8049a490 80d04d08 00000000
[ 206.898179] be60: 00000000 80d0da2c fee1dead 00000000 a806a000 00000058 00000000 80148b08
[ 206.906366] be80: 01234567 80148d8c a9858600 00000000 00000000 00000000 00000000 80d04d08
[ 206.914553] bea0: 00000000 00000000 a82741e0 a9858600 00000024 00000002 a9858608 00000005
[ 206.922740] bec0: 0000001e 8022c058 00000000 00000000 a806bf14 a9858600 00000000 a806befc
[ 206.930927] bee0: a806bf78 00000000 7ee12c30 8022c18c a806bef8 a806befc 00000000 00000001
[ 206.939115] bf00: 00000000 00000024 a806bf14 00000005 7ee13b34 7ee12c68 00000004 7ee13f20
[ 206.947302] bf20: 00000010 7ee12c7c 00000005 7ee12d04 0000000a 76e7dc00 00000001 80d0f140
[ 206.955490] bf40: ab637880 a974de40 60000013 80d0f140 ab6378a0 80d04d08 a8080470 a9858600
[ 206.963677] bf60: a9858600 00000000 00000000 8022c24c 00000000 80144310 00000000 00000000
[ 206.971864] bf80: 80101204 80d04d08 00000000 80d04d08 00000000 00000000 00000003 00000058
[ 206.980051] bfa0: 80101204 80101000 00000000 00000000 fee1dead 28121969 01234567 00000000
[ 206.988237] bfc0: 00000000 00000000 00000003 00000058 00000000 00000000 00000000 00000000
[ 206.996425] bfe0: 0049ffb0 7ee13d58 0048a84b 76f245a6 60000030 fee1dead 00000000 00000000
[ 207.004622] [<805cd4b0>] (ci_hdrc_remove_device) from [<805d62cc>] (ci_hdrc_imx_remove+0x20/0xe8)
[ 207.013509] [<805d62cc>] (ci_hdrc_imx_remove) from [<8049a490>] (device_shutdown+0x16c/0x218)
[ 207.022050] [<8049a490>] (device_shutdown) from [<80148b08>] (kernel_restart+0xc/0x50)
[ 207.029980] [<80148b08>] (kernel_restart) from [<80148d8c>] (sys_reboot+0xf4/0x1f0)
[ 207.037648] [<80148d8c>] (sys_reboot) from [<80101000>] (ret_fast_syscall+0x0/0x54)
[ 207.045308] Exception stack(0xa806bfa8 to 0xa806bff0)
[ 207.050368] bfa0: 00000000 00000000 fee1dead 28121969 01234567 00000000
[ 207.058554] bfc0: 00000000 00000000 00000003 00000058 00000000 00000000 00000000 00000000
[ 207.066737] bfe0: 0049ffb0 7ee13d58 0048a84b 76f245a6
[ 207.071799] Code: ebffffa8 e3a00000 e8bd8010 e92d4010 (e5904004)
[ 207.078021] ---[ end trace be47424e3fd46e9f ]---
[ 207.082647] Kernel panic - not syncing: Fatal exception
[ 207.087894] ---[ end Kernel panic - not syncing: Fatal exception ]---
c) the error path in combination with driver removal causes
imbalanced calls to the clk_*() and pm_()* APIs
a) happens because the original intended return value is
overwritten (with 0) by the return code of
regulator_disable() in ci_hdrc_imx_probe()'s error path
b) happens because ci_pdev is -EPROBE_DEFER, which causes
ci_hdrc_remove_device() to OOPS
Fix a) by being more careful in ci_hdrc_imx_probe()'s error
path and not overwriting the real error code
Fix b) by calling the respective cleanup functions during
remove only when needed (when ci_pdev != NULL, i.e. when
everything was initialised correctly). This also has the
side effect of not causing imbalanced clk_*() and pm_*()
API calls as part of the error code path.
Fixes:
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|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.