[linux-yocto] [linux-yocto-rt v5.0/standard/preempt-rt/base][PATCH 1/1] i915: Use local irq lock instead of irq disable regions

[Bruce Ashfield]

I've refreshed all the 5.0 -rt versions, so this no longer applies.

Can you check the latest changes on the branches and re-send if this
is still required.

Bruce

On Tue, May 28, 2019 at 11:56 PM Liwei Song <liwei.song at windriver.com> wrote:
>
> From: Jiping Ma <jiping.ma2 at windriver.com>
>
> Use a local_irq_lock as a replacement for irq off regions. We keep
> the semantic of irq-off in regard to the pool->lock and remain preemptible.
>
> BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:974
> in_atomic(): 0, irqs_disabled(): 1, pid: 192, name: systemd-udevd
> CPU: 2 PID: 192 Comm: systemd-udevd Not tainted 4.18.17-rt8-yocto-preempt-rt #1
> Hardware name: NUC5i3MYBE, BIOS MYBDWi30.86A.0017.2014.1127.1854 11/27/201
> Call Trace:
>  dump_stack+0x4f/0x73
>  ? migrate_enable+0x9e/0x3d0
>  ___might_sleep.cold.19+0xca/0xdb
>  rt_spin_lock+0x37/0x60
>  i915_request_retire+0x226/0x4a0 [i915]
>  i915_retire_requests+0xa2/0x110 [i915]
>  i915_gem_switch_to_kernel_context+0x2c/0x150 [i915]
>  ? __i915_request_add+0x27d/0x3f0 [i915]
>  i915_gem_init+0x323/0x470 [i915]
>  i915_driver_load+0xb3d/0xdf0 [i915]
>  i915_pci_probe+0x2b/0x40 [i915]
>  local_pci_probe+0x46/0x90
>  pci_device_probe+0x119/0x1a0
>  driver_probe_device+0x22f/0x300
>  __driver_attach+0xbd/0xd0
>  ? driver_probe_device+0x300/0x300
>  bus_for_each_dev+0x7b/0xc0
>  driver_attach+0x1e/0x20
>  bus_add_driver+0x1a4/0x1e0
>  driver_register+0x70/0xc0
>  __pci_register_driver+0x7f/0x90
>  ? 0xffffffffc02fb000
>  i915_init+0x55/0x58 [i915]
>  do_one_initcall+0x53/0x236
>  ? __might_sleep+0x4a/0x80
>  ? kmem_cache_alloc_trace+0x124/0x230
>  ? do_init_module+0x27/0x210
>  do_init_module+0x60/0x210
>  load_module+0x20dc/0x25f0
>  ? vfs_read+0x129/0x150
>  ? vfs_read+0x129/0x150
>  __se_sys_finit_module+0xc3/0xe0
>  ? __se_sys_finit_module+0xc3/0xe0
>  __x64_sys_finit_module+0x1a/0x20
>  do_syscall_64+0x4d/0xf0
>  entry_SYSCALL_64_after_hwframe+0x44/0xa9
> RIP: 0033:0x7ff026d71ba9
>
> Signed-off-by: Jiping Ma <jiping.ma2 at windriver.com>
> Signed-off-by: Liwei Song <liwei.song at windriver.com>
> ---
>  drivers/gpu/drm/i915/i915_request.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
> index ca95ab2f4cfa..4f01dc2ef3b3 100644
> --- a/drivers/gpu/drm/i915/i915_request.c
> +++ b/drivers/gpu/drm/i915/i915_request.c
> @@ -27,9 +27,12 @@
>  #include <linux/sched.h>
>  #include <linux/sched/clock.h>
>  #include <linux/sched/signal.h>
> +#include <linux/locallock.h>
>
>  #include "i915_drv.h"
>
> +static DEFINE_LOCAL_IRQ_LOCK(pendingb_lock);
> +
>  static const char *i915_fence_get_driver_name(struct dma_fence *fence)
>  {
>         return "i915";
> @@ -270,6 +273,8 @@ static void free_capture_list(struct i915_request *request)
>  static void __retire_engine_request(struct intel_engine_cs *engine,
>                                     struct i915_request *rq)
>  {
> +       unsigned long flags;
> +
>         GEM_TRACE("%s(%s) fence %llx:%d, global=%d, current %d\n",
>                   __func__, engine->name,
>                   rq->fence.context, rq->fence.seqno,
> @@ -278,7 +283,7 @@ static void __retire_engine_request(struct intel_engine_cs *engine,
>
>         GEM_BUG_ON(!i915_request_completed(rq));
>
> -       local_irq_disable();
> +       local_lock_irqsave(pendingb_lock, flags);
>
>         spin_lock(&engine->timeline.lock);
>         GEM_BUG_ON(!list_is_first(&rq->link, &engine->timeline.requests));
> @@ -296,7 +301,7 @@ static void __retire_engine_request(struct intel_engine_cs *engine,
>         }
>         spin_unlock(&rq->lock);
>
> -       local_irq_enable();
> +       local_unlock_irqrestore(pendingb_lock, flags);
>
>         /*
>          * The backing object for the context is done after switching to the
> --
> 2.18.1
>


-- 
- Thou shalt not follow the NULL pointer, for chaos and madness await
thee at its end
- "Use the force Harry" - Gandalf, Star Trek II