[PATCH 02/27] drm/i915/guc: Fix outstanding G2H accounting
Daniele Ceraolo Spurio
daniele.ceraolospurio at intel.com
Thu Aug 26 23:09:59 UTC 2021
On 8/25/2021 8:23 PM, Matthew Brost wrote:
> A small race that could result in incorrect accounting of the number
> of outstanding G2H. Basically prior to this patch we did not increment
> the number of outstanding G2H if we encoutered a GT reset while sending
> a H2G. This was incorrect as the context state had already been updated
> to anticipate a G2H response thus the counter should be incremented.
>
> Also always use helper when decrementing this value.
>
> Fixes: f4eb1f3fe946 ("drm/i915/guc: Ensure G2H response has space in buffer")
> Signed-off-by: Matthew Brost <matthew.brost at intel.com>
> Cc: <stable at vger.kernel.org>
> ---
> .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 23 ++++++++++---------
> 1 file changed, 12 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> index 69faa39da178..03a86da6011e 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> @@ -352,6 +352,12 @@ static inline void set_lrc_desc_registered(struct intel_guc *guc, u32 id,
> xa_unlock_irqrestore(&guc->context_lookup, flags);
> }
>
> +static void decr_outstanding_submission_g2h(struct intel_guc *guc)
> +{
> + if (atomic_dec_and_test(&guc->outstanding_submission_g2h))
> + wake_up_all(&guc->ct.wq);
> +}
> +
> static int guc_submission_send_busy_loop(struct intel_guc *guc,
> const u32 *action,
> u32 len,
> @@ -360,11 +366,12 @@ static int guc_submission_send_busy_loop(struct intel_guc *guc,
> {
> int err;
>
> - err = intel_guc_send_busy_loop(guc, action, len, g2h_len_dw, loop);
> -
> - if (!err && g2h_len_dw)
> + if (g2h_len_dw)
> atomic_inc(&guc->outstanding_submission_g2h);
>
> + err = intel_guc_send_busy_loop(guc, action, len, g2h_len_dw, loop);
> + GEM_BUG_ON(g2h_len_dw && err == -EBUSY);
AFAICS having a return g2h is not tied to not returning EBUSY, the only
way to avoid EBUSY seems to be for loop to be true. maybe have instead:
GEM_BUG_ON(g2h_len_dw && !loop);
earlier on?
Daniele
> +
> return err;
> }
>
> @@ -616,7 +623,7 @@ static void scrub_guc_desc_for_outstanding_g2h(struct intel_guc *guc)
> init_sched_state(ce);
>
> if (pending_enable || destroyed || deregister) {
> - atomic_dec(&guc->outstanding_submission_g2h);
> + decr_outstanding_submission_g2h(guc);
> if (deregister)
> guc_signal_context_fence(ce);
> if (destroyed) {
> @@ -635,7 +642,7 @@ static void scrub_guc_desc_for_outstanding_g2h(struct intel_guc *guc)
> intel_engine_signal_breadcrumbs(ce->engine);
> }
> intel_context_sched_disable_unpin(ce);
> - atomic_dec(&guc->outstanding_submission_g2h);
> + decr_outstanding_submission_g2h(guc);
> spin_lock_irqsave(&ce->guc_state.lock, flags);
> guc_blocked_fence_complete(ce);
> spin_unlock_irqrestore(&ce->guc_state.lock, flags);
> @@ -2583,12 +2590,6 @@ g2h_context_lookup(struct intel_guc *guc, u32 desc_idx)
> return ce;
> }
>
> -static void decr_outstanding_submission_g2h(struct intel_guc *guc)
> -{
> - if (atomic_dec_and_test(&guc->outstanding_submission_g2h))
> - wake_up_all(&guc->ct.wq);
> -}
> -
> int intel_guc_deregister_done_process_msg(struct intel_guc *guc,
> const u32 *msg,
> u32 len)
More information about the dri-devel
mailing list