Chris Wilson 326611ddff drm/i915: Mark up racy read of active rq->engine
As a virtual engine may change the rq->engine to point to the active
request in flight, we need to warn the compiler that an active request's
engine is volatile.

[   95.017686] write (marked) to 0xffff8881e8386b10 of 8 bytes by interrupt on cpu 2:
[   95.018123]  execlists_dequeue+0x762/0x2150 [i915]
[   95.018539]  __execlists_submission_tasklet+0x48/0x60 [i915]
[   95.018955]  execlists_submission_tasklet+0xd3/0x170 [i915]
[   95.018986]  tasklet_action_common.isra.0+0x42/0xa0
[   95.019016]  __do_softirq+0xd7/0x2cd
[   95.019043]  irq_exit+0xbe/0xe0
[   95.019068]  irq_work_interrupt+0xf/0x20
[   95.019491]  i915_request_retire+0x2c5/0x670 [i915]
[   95.019937]  retire_requests+0xa1/0xf0 [i915]
[   95.020348]  engine_retire+0xa1/0xe0 [i915]
[   95.020376]  process_one_work+0x3b1/0x690
[   95.020403]  worker_thread+0x80/0x670
[   95.020429]  kthread+0x19a/0x1e0
[   95.020454]  ret_from_fork+0x1f/0x30
[   95.020476]
[   95.020498] read to 0xffff8881e8386b10 of 8 bytes by task 8909 on cpu 3:
[   95.020918]  __i915_request_commit+0x177/0x220 [i915]
[   95.021329]  i915_gem_do_execbuffer+0x38c4/0x4e50 [i915]
[   95.021750]  i915_gem_execbuffer2_ioctl+0x2c3/0x580 [i915]
[   95.021784]  drm_ioctl_kernel+0xe4/0x120
[   95.021809]  drm_ioctl+0x297/0x4c7
[   95.021832]  ksys_ioctl+0x89/0xb0
[   95.021865]  __x64_sys_ioctl+0x42/0x60
[   95.021901]  do_syscall_64+0x6e/0x2c0
[   95.021927]  entry_SYSCALL_64_after_hwframe+0x44/0xa9

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200310142403.5953-1-chris@chris-wilson.co.uk
2020-03-10 23:12:38 +00:00
2020-03-03 09:56:43 +00:00
2020-02-13 16:30:22 +01:00
2020-01-18 09:19:18 -05:00
2020-02-16 13:16:59 -08:00

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.
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