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FAILED: patch "[PATCH] drm/i915/gem: Delay tracking the GEM context until it is" failed to apply to 5.4-stable tree

PATCH [email protected] 1 participant 1 message Sep 21, 2020

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Stable branch DRM drivers Intel i915
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The patch below does not apply to the 5.4-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From e7d95527f27a6d9edcffbd74eee38e5cb6b91785 Mon Sep 17 00:00:00 2001
From: Chris Wilson <[email protected]>
Date: Thu, 30 Jul 2020 10:28:56 +0100
Subject: [PATCH] drm/i915/gem: Delay tracking the GEM context until it is
registered

Avoid exposing a partially constructed context by deferring the list_add() from the initial construction to the end of registration. Otherwise, if we peek into the list of contexts from inside debugfs, we may see the partially constructed context and chase down some dangling incomplete pointers.

Reported-by CQ Tang <[email protected]>
Fixes 3aa9945a528e ("drm/i915: Separate GEM context construction and registration to userspace")

References: f6e8aa387171 ("drm/i915: Report the number of closed vma held by each context in debugfs")

Signed-off-by Chris Wilson <[email protected]>
Cc Tvrtko Ursulin <[email protected]>
Cc CQ Tang <[email protected]>
Cc <[email protected]> # v5.2+
Reviewed-by Mika Kuoppala <[email protected]>
Link https://patchwork.freedesktop.org/patch/msgid/[email protected]
Signed-off-by Rodrigo Vivi <[email protected]>
Signed-off-by Joonas Lahtinen <[email protected]>
(cherry picked from commit eb4dedae920a07c485328af3da2202ec5184fb17)
Signed-off-by Jani Nikula <[email protected]>
drivers/gpu/drm/i915/gem/i915_gem_context.c +11 -5
index d0bdb6d447ed..efc4ba34c06e 100644
@@ -713,6 +713,7 @@ __create_context(struct drm_i915_private *i915)
 	ctx->i915 = i915;
 	ctx->sched.priority = I915_USER_PRIORITY(I915_PRIORITY_NORMAL);
 	mutex_init(&ctx->mutex);
+	INIT_LIST_HEAD(&ctx->link);
 
 	spin_lock_init(&ctx->stale.lock);
 	INIT_LIST_HEAD(&ctx->stale.engines);

@@ -740,10 +741,6 @@ __create_context(struct drm_i915_private *i915)
 	for (i = 0; i < ARRAY_SIZE(ctx->hang_timestamp); i++)
 		ctx->hang_timestamp[i] = jiffies - CONTEXT_FAST_HANG_JIFFIES;
 
-	spin_lock(&i915->gem.contexts.lock);
-	list_add_tail(&ctx->link, &i915->gem.contexts.list);
-	spin_unlock(&i915->gem.contexts.lock);
-
 	return ctx;
 
 err_free:

@@ -931,6 +928,7 @@ static int gem_context_register(struct i915_gem_context *ctx,
 				struct drm_i915_file_private *fpriv,
 				u32 *id)
 {
+	struct drm_i915_private *i915 = ctx->i915;
 	struct i915_address_space *vm;
 	int ret;
 

@@ -949,8 +947,16 @@ static int gem_context_register(struct i915_gem_context *ctx,
 	/* And finally expose ourselves to userspace via the idr */
 	ret = xa_alloc(&fpriv->context_xa, id, ctx, xa_limit_32b, GFP_KERNEL);
 	if (ret)
-		put_pid(fetch_and_zero(&ctx->pid));
+		goto err_pid;
+
+	spin_lock(&i915->gem.contexts.lock);
+	list_add_tail(&ctx->link, &i915->gem.contexts.list);
+	spin_unlock(&i915->gem.contexts.lock);
+
+	return 0;
 
+err_pid:
+	put_pid(fetch_and_zero(&ctx->pid));
 	return ret;
 }