On Tue, Feb 28, 2017 at 09:09:04AM +0000, Chris Wilson wrote:
> Following the use of dma_fence_signal() from within our interrupt
> handler, we need to make guc->wq_lock also irq-safe. This was done
> previously as part of the guc scheduler patch (which also started
> mixing our fences with the interrupt handler), but is now required to
> fix the current guc submission backend.
>
> v2: __i915_guc_submit needs the full irqsave spinlock.
>
> Fixes: 67b807a89230 ("drm/i915: Delay disabling the user interrupt for breadcrumbs")
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
> Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/i915_guc_submission.c | 14 ++++++++++----
> 1 file changed, 10 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_guc_submission.c b/drivers/gpu/drm/i915/i915_guc_submission.c
> index beec88a30347..cbe0f509699c 100644
> --- a/drivers/gpu/drm/i915/i915_guc_submission.c
> +++ b/drivers/gpu/drm/i915/i915_guc_submission.c
> @@ -348,7 +348,7 @@ int i915_guc_wq_reserve(struct drm_i915_gem_request *request)
> u32 freespace;
> int ret;
>
> - spin_lock(&client->wq_lock);
> + spin_lock_irq(&client->wq_lock);
> freespace = CIRC_SPACE(client->wq_tail, desc->head, client->wq_size);
> freespace -= client->wq_rsvd;
> if (likely(freespace >= wqi_size)) {
> @@ -358,7 +358,7 @@ int i915_guc_wq_reserve(struct drm_i915_gem_request *request)
> client->no_wq_space++;
> ret = -EAGAIN;
> }
> - spin_unlock(&client->wq_lock);
> + spin_unlock_irq(&client->wq_lock);
>
> return ret;
> }
> @@ -367,12 +367,13 @@ void i915_guc_wq_unreserve(struct drm_i915_gem_request *request)
> {
> const size_t wqi_size = sizeof(struct guc_wq_item);
> struct i915_guc_client *client = request->i915->guc.execbuf_client;
> + unsigned long flags;
>
> GEM_BUG_ON(READ_ONCE(client->wq_rsvd) < wqi_size);
>
> - spin_lock(&client->wq_lock);
> + spin_lock_irqsave(&client->wq_lock, flags);
> client->wq_rsvd -= wqi_size;
> - spin_unlock(&client->wq_lock);
> + spin_unlock_irqrestore(&client->wq_lock, flags);
Should we just use cmpxchg here?
unsigned int new, old;
do {
old = client->wq_rsvd;
new = old - wqi_size;
} while (cmpxchg(&clint->wq_rsvd, old, new) != old);
> }
>
> /* Construct a Work Item and append it to the GuC's Work Queue */
> @@ -951,10 +952,15 @@ int i915_guc_submission_enable(struct drm_i915_private *dev_priv)
> engine->schedule = NULL;
>
> /* Replay the current set of previously submitted requests */
> + spin_lock_irq(&engine->timeline->lock);
> list_for_each_entry(rq, &engine->timeline->requests, link) {
> + spin_lock(&client->wq_lock);
> client->wq_rsvd += sizeof(struct guc_wq_item);
> + spin_unlock(&client->wq_lock);
And here.
So perhaps:
static void guc_wq_add_reserved(client, int delta);
-Chris
--
Chris Wilson, Intel Open Source Technology Centre
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