6b4877c7bd
If FF request comes in while uinput device is going away,
uinput_request_send() will fail with -ENODEV, and uinput_request_submit()
will attempt to mark the slot as unused by calling uinput_request_done().
Unfortunately in this case we haven't initialized request->done completion
yet, and we get a crash:
[ 39.402036] BUG: spinlock bad magic on CPU#1, fftest/3108
[ 39.402046] lock: 0xffff88006a93bb00, .magic: 00000000, .owner: /39, .owner_cpu: 1217155072
[ 39.402055] CPU: 1 PID: 3108 Comm: fftest Tainted: G W 4.13.0+ #15
[ 39.402059] Hardware name: LENOVO 20HQS0EG02/20HQS0EG02, BIOS N1MET37W (1.22 ) 07/04/2017
[ 39.402064] 0000000000000086 f0fad82f3ceaa120 ffff88006a93b9a0 ffffffff9de941bb
[ 39.402077] ffff88026df8ae00 ffff88006a93bb00 ffff88006a93b9c0 ffffffff9dca62b7
[ 39.402088] ffff88006a93bb00 ffff88006a93baf8 ffff88006a93b9e0 ffffffff9dca62e7
[ 39.402099] Call Trace:
[ 39.402112] [<ffffffff9de941bb>] dump_stack+0x4d/0x63
[ 39.402123] [<ffffffff9dca62b7>] spin_dump+0x97/0x9c
[ 39.402130] [<ffffffff9dca62e7>] spin_bug+0x2b/0x2d
[ 39.402138] [<ffffffff9dca6373>] do_raw_spin_lock+0x28/0xfd
[ 39.402147] [<ffffffff9e3055cd>] _raw_spin_lock_irqsave+0x19/0x1f
[ 39.402154] [<ffffffff9dca05b7>] complete+0x1d/0x48
[ 39.402162] [<ffffffffc04f30af>] 0xffffffffc04f30af
[ 39.402167] [<ffffffffc04f468c>] 0xffffffffc04f468c
[ 39.402177] [<ffffffff9dd59c16>] ? __slab_free+0x22f/0x359
[ 39.402184] [<ffffffff9dcc13e9>] ? tk_clock_read+0xc/0xe
[ 39.402189] [<ffffffffc04f471f>] 0xffffffffc04f471f
[ 39.402195] [<ffffffff9dc9ffe5>] ? __wake_up+0x44/0x4b
[ 39.402200] [<ffffffffc04f3240>] ? 0xffffffffc04f3240
[ 39.402207] [<ffffffff9e0f57f3>] erase_effect+0xa1/0xd2
[ 39.402214] [<ffffffff9e0f58c6>] input_ff_flush+0x43/0x5c
[ 39.402219] [<ffffffffc04f32ad>] 0xffffffffc04f32ad
[ 39.402227] [<ffffffff9e0f174f>] input_flush_device+0x3d/0x51
[ 39.402234] [<ffffffff9e0f69ae>] evdev_flush+0x49/0x5c
[ 39.402243] [<ffffffff9dd62d6e>] filp_close+0x3f/0x65
[ 39.402253] [<ffffffff9dd7dcf7>] put_files_struct+0x66/0xc1
[ 39.402261] [<ffffffff9dd7ddeb>] exit_files+0x47/0x4e
[ 39.402270] [<ffffffff9dc6b329>] do_exit+0x483/0x969
[ 39.402278] [<ffffffff9dc73211>] ? recalc_sigpending_tsk+0x3d/0x44
[ 39.402285] [<ffffffff9dc6c7a2>] do_group_exit+0x42/0xb0
[ 39.402293] [<ffffffff9dc767e1>] get_signal+0x58d/0x5bf
[ 39.402300] [<ffffffff9dc03701>] do_signal+0x37/0x53e
[ 39.402307] [<ffffffff9e0f8401>] ? evdev_ioctl_handler+0xac8/0xb04
[ 39.402314] [<ffffffff9e0f8464>] ? evdev_ioctl+0x10/0x12
[ 39.402321] [<ffffffff9dd74cfa>] ? do_vfs_ioctl+0x42e/0x501
[ 39.402328] [<ffffffff9dc0170e>] prepare_exit_to_usermode+0x66/0x90
[ 39.402333] [<ffffffff9dc0181b>] syscall_return_slowpath+0xe3/0xec
[ 39.402339] [<ffffffff9e305b7b>] int_ret_from_sys_call+0x25/0x8f
While we could solve this by simply initializing the completion earlier, we
are better off rearranging the code a bit so we avoid calling complete() on
requests that we did not send out. This patch consolidates marking request
slots as free in one place (in uinput_request_submit(), the same place
where we acquire them) and having everyone else simply signal completion
of the requests.
Fixes: 00ce756ce5 ("Input: uinput - mark failed submission requests as free")
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. 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.