linux-kernel - [PATCH 5.15 244/279] drm/i915/guc: Dont drop ce->guc

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Message-Id: <20211124115727.156660561@linuxfoundation.org>
Date:   Wed, 24 Nov 2021 12:58:51 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Daniele Ceraolo Spurio <daniele.ceraolospurio@...el.com>,
        Matthew Brost <matthew.brost@...el.com>,
        John Harrison <John.C.Harrison@...el.com>
Subject: [PATCH 5.15 244/279] drm/i915/guc: Dont drop ce->guc_active.lock when unwinding context

From: Matthew Brost <matthew.brost@...el.com>

commit 88209a8ecb8b8752322908a3c3362a001bdc3a39 upstream.

Don't drop ce->guc_active.lock when unwinding a context after reset.
At one point we had to drop this because of a lock inversion but that is
no longer the case. It is much safer to hold the lock so let's do that.

Fixes: eb5e7da736f3 ("drm/i915/guc: Reset implementation for new GuC interface")
Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@...el.com>
Signed-off-by: Matthew Brost <matthew.brost@...el.com>
Cc: <stable@...r.kernel.org>
Signed-off-by: John Harrison <John.C.Harrison@...el.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210909164744.31249-5-matthew.brost@intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c |    4 ----
 1 file changed, 4 deletions(-)

--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
@@ -814,8 +814,6 @@ __unwind_incomplete_requests(struct inte
 			continue;
 
 		list_del_init(&rq->sched.link);
-		spin_unlock(&ce->guc_active.lock);
-
 		__i915_request_unsubmit(rq);
 
 		/* Push the request back into the queue for later resubmission. */
@@ -828,8 +826,6 @@ __unwind_incomplete_requests(struct inte
 
 		list_add_tail(&rq->sched.link, pl);
 		set_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags);
-
-		spin_lock(&ce->guc_active.lock);
 	}
 	spin_unlock(&ce->guc_active.lock);
 	spin_unlock_irqrestore(&sched_engine->lock, flags);