linux-kernel - [PATCH AUTOSEL 4.14 006/170] gpu: ipu-v3: image-convert: Prevent race between run and unprepare

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Message-Id: <20190128161200.55107-6-sashal@kernel.org>
Date:   Mon, 28 Jan 2019 11:09:16 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Steve Longerbeam <slongerbeam@...il.com>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Sasha Levin <sashal@...nel.org>,
        dri-devel@...ts.freedesktop.org
Subject: [PATCH AUTOSEL 4.14 006/170] gpu: ipu-v3: image-convert: Prevent race between run and unprepare

From: Steve Longerbeam <slongerbeam@...il.com>

[ Upstream commit 819bec35c8c9706185498c9222bd244e0781ad35 ]

Prevent possible race by parallel threads between ipu_image_convert_run()
and ipu_image_convert_unprepare(). This involves setting ctx->aborting
to true unconditionally so that no new job runs can be queued during
unprepare, and holding the ctx->aborting flag until the context is freed.

Note that the "normal" ipu_image_convert_abort() case (e.g. not during
context unprepare) should clear the ctx->aborting flag after aborting
any active run and clearing the context's pending queue. This is because
it should be possible to continue to use the conversion context and queue
more runs after an abort.

Signed-off-by: Steve Longerbeam <slongerbeam@...il.com>
Tested-by: Philipp Zabel <p.zabel@...gutronix.de>
Signed-off-by: Philipp Zabel <p.zabel@...gutronix.de>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/ipu-v3/ipu-image-convert.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/ipu-v3/ipu-image-convert.c b/drivers/gpu/ipu-v3/ipu-image-convert.c
index 524a717ab28e..a5e33d58e02f 100644
--- a/drivers/gpu/ipu-v3/ipu-image-convert.c
+++ b/drivers/gpu/ipu-v3/ipu-image-convert.c
@@ -1518,7 +1518,7 @@ int ipu_image_convert_queue(struct ipu_image_convert_run *run)
 EXPORT_SYMBOL_GPL(ipu_image_convert_queue);
 
 /* Abort any active or pending conversions for this context */
-void ipu_image_convert_abort(struct ipu_image_convert_ctx *ctx)
+static void __ipu_image_convert_abort(struct ipu_image_convert_ctx *ctx)
 {
 	struct ipu_image_convert_chan *chan = ctx->chan;
 	struct ipu_image_convert_priv *priv = chan->priv;
@@ -1545,7 +1545,7 @@ void ipu_image_convert_abort(struct ipu_image_convert_ctx *ctx)
 
 	need_abort = (run_count || active_run);
 
-	ctx->aborting = need_abort;
+	ctx->aborting = true;
 
 	spin_unlock_irqrestore(&chan->irqlock, flags);
 
@@ -1566,7 +1566,11 @@ void ipu_image_convert_abort(struct ipu_image_convert_ctx *ctx)
 		dev_warn(priv->ipu->dev, "%s: timeout\n", __func__);
 		force_abort(ctx);
 	}
+}
 
+void ipu_image_convert_abort(struct ipu_image_convert_ctx *ctx)
+{
+	__ipu_image_convert_abort(ctx);
 	ctx->aborting = false;
 }
 EXPORT_SYMBOL_GPL(ipu_image_convert_abort);
@@ -1580,7 +1584,7 @@ void ipu_image_convert_unprepare(struct ipu_image_convert_ctx *ctx)
 	bool put_res;
 
 	/* make sure no runs are hanging around */
-	ipu_image_convert_abort(ctx);
+	__ipu_image_convert_abort(ctx);
 
 	dev_dbg(priv->ipu->dev, "%s: task %u: removing ctx %p\n", __func__,
 		chan->ic_task, ctx);
-- 
2.19.1