drm/i915/gt: Use spin_lock_irqsave() in interruptible context

spin_lock/unlock() functions used in interrupt contexts could
result in a deadlock, as seen in GitLab issue #13399,
which occurs when interrupt comes in while holding a lock.

Try to remedy the problem by saving irq state before spin lock
acquisition.

v2: add irqs' state save/restore calls to all locks/unlocks in
 signal_irq_work() execution (Maciej)

v3: use with spin_lock_irqsave() in guc_lrc_desc_unpin() instead
 of other lock/unlock calls and add Fixes and Cc tags (Tvrtko);
 change title and commit message

Fixes: 2f2cc53 ("drm/i915/guc: Close deregister-context race against CT-loss")
Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/13399
Signed-off-by: Krzysztof Karas <[email protected]>
Cc: <[email protected]> # v6.9+
Reviewed-by: Maciej Patelczyk <[email protected]>
Reviewed-by: Andi Shyti <[email protected]>
Signed-off-by: Andi Shyti <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/pusppq5ybyszau2oocboj3mtj5x574gwij323jlclm5zxvimmu@mnfg6odxbpsv

Author: KKaras169169

drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c

@@ -3449,10 +3449,10 @@ static inline int guc_lrc_desc_unpin(struct intel_context *ce)
 	 */
 	ret = deregister_context(ce, ce->guc_id.id);
 	if (ret) {
-		spin_lock(&ce->guc_state.lock);
+		spin_lock_irqsave(&ce->guc_state.lock, flags);
 		set_context_registered(ce);
 		clr_context_destroyed(ce);
-		spin_unlock(&ce->guc_state.lock);
+		spin_unlock_irqrestore(&ce->guc_state.lock, flags);
 		/*
 		 * As gt-pm is awake at function entry, intel_wakeref_put_async merely decrements
 		 * the wakeref immediately but per function spec usage call this after unlock.