From: Matthew Brost <matthew.brost@intel.com>
To: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org
Subject: Re: [PATCH 02/27] drm/i915/guc: Fix outstanding G2H accounting
Date: Thu, 26 Aug 2021 18:36:50 -0700 [thread overview]
Message-ID: <20210827013650.GA9019@jons-linux-dev-box> (raw)
In-Reply-To: <3fde98f9-b408-63cf-ea31-779bf477b68e@intel.com>
On Thu, Aug 26, 2021 at 04:09:59PM -0700, Daniele Ceraolo Spurio wrote:
>
>
> 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@intel.com>
> > Cc: <stable@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?
>
Yep, that is better. Can you respin this for me while I'm out?
Matt
> 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)
>
next prev parent reply other threads:[~2021-08-27 1:42 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-26 3:23 [PATCH 00/27] Clean up GuC CI failures, simplify locking, and kernel DOC Matthew Brost
2021-08-26 3:23 ` [PATCH 01/27] drm/i915/guc: Fix blocked context accounting Matthew Brost
2021-08-26 3:23 ` [PATCH 02/27] drm/i915/guc: Fix outstanding G2H accounting Matthew Brost
2021-08-26 23:09 ` Daniele Ceraolo Spurio
2021-08-27 1:36 ` Matthew Brost [this message]
2021-08-26 3:23 ` [PATCH 03/27] drm/i915/guc: Unwind context requests in reverse order Matthew Brost
2021-08-26 3:23 ` [PATCH 04/27] drm/i915/guc: Don't drop ce->guc_active.lock when unwinding context Matthew Brost
2021-08-26 3:23 ` [PATCH 05/27] drm/i915/guc: Process all G2H message at once in work queue Matthew Brost
2021-08-26 3:23 ` [PATCH 06/27] drm/i915/guc: Workaround reset G2H is received after schedule done G2H Matthew Brost
2021-08-26 23:11 ` Daniele Ceraolo Spurio
2021-08-26 3:23 ` [PATCH 07/27] Revert "drm/i915/gt: Propagate change in error status to children on unhold" Matthew Brost
2021-08-26 3:23 ` [PATCH 08/27] drm/i915/selftests: Add a cancel request selftest that triggers a reset Matthew Brost
2021-08-26 9:32 ` [Intel-gfx] " Tvrtko Ursulin
2021-08-26 14:00 ` Matthew Brost
2021-08-26 3:23 ` [PATCH 09/27] drm/i915/guc: Kick tasklet after queuing a request Matthew Brost
2021-08-26 3:23 ` [PATCH 10/27] drm/i915/guc: Don't enable scheduling on a banned context, guc_id invalid, not registered Matthew Brost
2021-08-26 3:23 ` [PATCH 11/27] drm/i915/guc: Copy whole golden context, set engine state size of subset Matthew Brost
2021-08-26 23:21 ` Daniele Ceraolo Spurio
2021-08-26 23:33 ` [Intel-gfx] " John Harrison
2021-08-26 3:23 ` [PATCH 12/27] drm/i915/selftests: Add initial GuC selftest for scrubbing lost G2H Matthew Brost
2021-08-26 3:23 ` [PATCH 13/27] drm/i915/guc: Take context ref when cancelling request Matthew Brost
2021-08-26 3:23 ` [PATCH 14/27] drm/i915/guc: Don't touch guc_state.sched_state without a lock Matthew Brost
2021-08-26 3:23 ` [PATCH 15/27] drm/i915/guc: Reset LRC descriptor if register returns -ENODEV Matthew Brost
2021-08-26 3:23 ` [PATCH 16/27] drm/i915: Allocate error capture in nowait context Matthew Brost
2021-08-26 16:18 ` [Intel-gfx] " Matthew Brost
2021-08-26 16:21 ` Daniel Vetter
2021-08-26 3:23 ` [PATCH 17/27] drm/i915/guc: Flush G2H work queue during reset Matthew Brost
2021-08-26 3:23 ` [PATCH 18/27] drm/i915/guc: Release submit fence from an irq_work Matthew Brost
2021-08-26 3:23 ` [PATCH 19/27] drm/i915/guc: Move guc_blocked fence to struct guc_state Matthew Brost
2021-08-26 3:23 ` [PATCH 20/27] drm/i915/guc: Rework and simplify locking Matthew Brost
2021-08-26 3:23 ` [PATCH 21/27] drm/i915/guc: Proper xarray usage for contexts_lookup Matthew Brost
2021-08-26 3:23 ` [PATCH 22/27] drm/i915/guc: Drop pin count check trick between sched_disable and re-pin Matthew Brost
2021-08-26 3:23 ` [PATCH 23/27] drm/i915/guc: Move GuC priority fields in context under guc_active Matthew Brost
2021-08-26 23:26 ` Daniele Ceraolo Spurio
2021-08-26 3:23 ` [PATCH 24/27] drm/i915/guc: Move fields protected by guc->contexts_lock into sub structure Matthew Brost
2021-08-26 3:23 ` [PATCH 25/27] drm/i915/guc: Drop guc_active move everything into guc_state Matthew Brost
2021-08-26 3:23 ` [PATCH 26/27] drm/i915/guc: Add GuC kernel doc Matthew Brost
2021-08-31 19:04 ` [Intel-gfx] " John Harrison
2021-08-26 3:23 ` [PATCH 27/27] drm/i915/guc: Drop static inline functions intel_guc_submission.c Matthew Brost
2021-08-31 19:09 ` [Intel-gfx] " John Harrison
-- strict thread matches above, loose matches on Subject: below --
2021-08-19 6:16 [PATCH 00/27] Clean up GuC CI failures, simplify locking, and kernel DOC Matthew Brost
2021-08-19 6:16 ` [PATCH 02/27] drm/i915/guc: Fix outstanding G2H accounting Matthew Brost
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