forked from Minki/linux
mainlining shenanigans
6d71021ab3
An application can try to set brightness before all the initialization is done, in particular before the workqueue is initialized with the call to led_init_core(). Here's a WARNING easy to trigger: [ 36.780813] WARNING: CPU: 3 PID: 1411 at ../kernel/workqueue.c:1444 __queue_work+0x37b/0x420 [ 36.780815] Modules linked in: ... [ 36.780868] CPU: 3 PID: 1411 Comm: systemd-backlig Not tainted 4.16.9-1-default #1 openSUSE Tumbleweed (unreleased) [ 36.780868] Hardware name: Dell Inc. Precision 5510/0N8J4R, BIOS 1.6.1 12/11/2017 [ 36.780870] RIP: 0010:__queue_work+0x37b/0x420 [ 36.780871] RSP: 0018:ffffaced048b7d78 EFLAGS: 00010086 [ 36.780873] RAX: 0000000000000000 RBX: ffffffffb3f01440 RCX: 0000000000000000 [ 36.780873] RDX: ffffffffc05a90d8 RSI: 0000000000000000 RDI: ffff8eac7dce2700 [ 36.780874] RBP: ffff8ea547c16400 R08: ffff8ea547800000 R09: ffff8eac7dc22700 [ 36.780875] R10: 0000000000000000 R11: 0000000000000040 R12: 0000000000000003 [ 36.780876] R13: 0000000000000200 R14: ffffffffc05a90d0 R15: ffff8eac7dce8600 [ 36.780877] FS: 00007f871e61cf40(0000) GS:ffff8eac7dcc0000(0000) knlGS:0000000000000000 [ 36.780878] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 36.780879] CR2: 000055c91115e308 CR3: 0000000883ee0005 CR4: 00000000003606e0 [ 36.780880] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 36.780880] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 36.780881] Call Trace: [ 36.780886] queue_work_on+0x81/0x90 [ 36.780889] brightness_store+0x5d/0x90 [ 36.780892] kernfs_fop_write+0x105/0x180 [ 36.780894] __vfs_write+0x26/0x150 [ 36.780897] ? common_file_perm+0x51/0x150 [ 36.780900] ? security_file_permission+0x3c/0xb0 [ 36.780901] vfs_write+0xad/0x1a0 [ 36.780903] SyS_write+0x42/0x90 [ 36.780906] do_syscall_64+0x76/0x140 [ 36.780908] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 36.780910] RIP: 0033:0x7f871dd04c94 [ 36.780910] RSP: 002b:00007ffeb3a57d38 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 [ 36.780912] RAX: ffffffffffffffda RBX: 000055c91115c810 RCX: 00007f871dd04c94 [ 36.780912] RDX: 0000000000000001 RSI: 000055c91115c810 RDI: 0000000000000004 [ 36.780913] RBP: 00007ffeb3a57e10 R08: 0000000000000003 R09: 0000000000000000 [ 36.780914] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 [ 36.780914] R13: 000055c911158f30 R14: 000055c90f3a9a4e R15: 0000000000000004 [ 36.780917] Code: 74 18 e8 49 80 00 00 48 85 c0 74 0e 48 8b 40 20 48 3b 68 08 0f 84 c2 fc ff ff 0f 0b 48 83 c4 10 5b 5d 41 5c 41 5d 41 5e 41 5f c3 <0f> 0b e9 82 fd ff ff 83 cd 02 49 8d 57 60 e9 69 fd ff ff 80 3d [ 36.780942] ---[ end trace 1fce4edad54c4017 ]--- This patch initializes and acquires the led_access mutex early in the of_led_classdev_register function, so that any application trying to write to sysfs to set brightness will block until initialization ends. Signed-off-by: Luis Henriques <lhenriques@suse.com> Acked-by: Pavel Machek <pavel@ucw.cz> Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com> |
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| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| firmware | ||
| 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.
See Documentation/00-INDEX for a list of what is contained in each file.
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.