a79ca656b6
If the backend wishes to defer the wakeref parking, make it responsible for unlocking the wakeref (i.e. bumping the counter). This allows it to time the unlock much more carefully in case it happens to needs the wakeref to be active during its deferral. For instance, during engine parking we may choose to emit an idle barrier (a request). To do so, we borrow the engine->kernel_context timeline and to ensure exclusive access we keep the engine->wakeref.count as 0. However, to submit that request to HW may require a intel_engine_pm_get() (e.g. to keep the submission tasklet alive) and before we allow that we have to rewake our wakeref to avoid a recursive deadlock. <4> [257.742916] IRQs not enabled as expected <4> [257.742930] WARNING: CPU: 0 PID: 0 at kernel/softirq.c:169 __local_bh_enable_ip+0xa9/0x100 <4> [257.742936] Modules linked in: vgem snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_codec_generic i915 btusb btrtl btbcm btintel snd_hda_intel snd_intel_nhlt bluetooth snd_hda_codec coretemp snd_hwdep crct10dif_pclmul snd_hda_core crc32_pclmul ecdh_generic ecc ghash_clmulni_intel snd_pcm r8169 realtek lpc_ich prime_numbers i2c_hid <4> [257.742991] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G U W 5.3.0-rc3-g5d0a06cd532c-drmtip_340+ #1 <4> [257.742998] Hardware name: GIGABYTE GB-BXBT-1900/MZBAYAB-00, BIOS F6 02/17/2015 <4> [257.743008] RIP: 0010:__local_bh_enable_ip+0xa9/0x100 <4> [257.743017] Code: 37 5b 5d c3 8b 80 50 08 00 00 85 c0 75 a9 80 3d 0b be 25 01 00 75 a0 48 c7 c7 f3 0c 06 ac c6 05 fb bd 25 01 01 e8 77 84 ff ff <0f> 0b eb 89 48 89 ef e8 3b 41 06 00 eb 98 e8 e4 5c f4 ff 5b 5d c3 <4> [257.743025] RSP: 0018:ffffa78600003cb8 EFLAGS: 00010086 <4> [257.743035] RAX: 0000000000000000 RBX: 0000000000000200 RCX: 0000000000010302 <4> [257.743042] RDX: 0000000080010302 RSI: 0000000000000000 RDI: 00000000ffffffff <4> [257.743050] RBP: ffffffffc0494bb3 R08: 0000000000000000 R09: 0000000000000001 <4> [257.743058] R10: 0000000014c8f0e9 R11: 00000000fee2ff8e R12: ffffa23ba8c38008 <4> [257.743065] R13: ffffa23bacc579c0 R14: ffffa23bb7db0f60 R15: ffffa23b9cc8c430 <4> [257.743074] FS: 0000000000000000(0000) GS:ffffa23bbba00000(0000) knlGS:0000000000000000 <4> [257.743082] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 <4> [257.743089] CR2: 00007fe477b20778 CR3: 000000011f72a000 CR4: 00000000001006f0 <4> [257.743096] Call Trace: <4> [257.743104] <IRQ> <4> [257.743265] __i915_request_commit+0x240/0x5d0 [i915] <4> [257.743427] ? __i915_request_create+0x228/0x4c0 [i915] <4> [257.743584] __engine_park+0x64/0x250 [i915] <4> [257.743730] ____intel_wakeref_put_last+0x1c/0x70 [i915] <4> [257.743878] i915_sample+0x2ee/0x310 [i915] <4> [257.744030] ? i915_pmu_cpu_offline+0xb0/0xb0 [i915] <4> [257.744040] __hrtimer_run_queues+0x11e/0x4b0 <4> [257.744068] hrtimer_interrupt+0xea/0x250 <4> [257.744079] ? lockdep_hardirqs_off+0x79/0xd0 <4> [257.744101] smp_apic_timer_interrupt+0x96/0x280 <4> [257.744114] apic_timer_interrupt+0xf/0x20 <4> [257.744125] RIP: 0010:__do_softirq+0xb3/0x4ae v2: Keep the priority_hint assert v3: That assert was desperately trying to point out my bug. Sorry, little assert. Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=111378 Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com> Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com> Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20190813190705.23869-1-chris@chris-wilson.co.uk |
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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.