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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Rob Clark <robdclark@chromium.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.15 221/846] drm/msm/gpu: Dont allow zero fence_id
Date:   Mon, 24 Jan 2022 19:35:38 +0100
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From: Rob Clark <robdclark@chromium.org>

[ Upstream commit ca3ffcbeb0c866d9b0cb38eaa2bd4416597b5966 ]

Elsewhere we treat zero as "no fence" and __msm_gem_submit_destroy()
skips removal from fence_idr.  We could alternately change this to use
negative values for "no fence" but I think it is more clear to not allow
zero as a valid fence_id.

Signed-off-by: Rob Clark <robdclark@chromium.org>
Fixes: a61acbbe9cf8 ("drm/msm: Track "seqno" fences by idr")
Link: https://lore.kernel.org/r/20211129182344.292609-1-robdclark@gmail.com
Signed-off-by: Rob Clark <robdclark@chromium.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/gpu/drm/msm/msm_gem_submit.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/msm/msm_gem_submit.c b/drivers/gpu/drm/msm/msm_gem_submit.c
index d9aef97eb93ad..7fb7ff043bcd7 100644
--- a/drivers/gpu/drm/msm/msm_gem_submit.c
+++ b/drivers/gpu/drm/msm/msm_gem_submit.c
@@ -887,7 +887,7 @@ int msm_ioctl_gem_submit(struct drm_device *dev, void *data,
 	 * to the underlying fence.
 	 */
 	submit->fence_id = idr_alloc_cyclic(&queue->fence_idr,
-			submit->user_fence, 0, INT_MAX, GFP_KERNEL);
+			submit->user_fence, 1, INT_MAX, GFP_KERNEL);
 	if (submit->fence_id < 0) {
 		ret = submit->fence_id = 0;
 		submit->fence_id = 0;
-- 
2.34.1