linux-kernel - [PATCH v2 08/10] misc: fastrpc: Safekeep mmaps on interrupted invoke

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Date:   Fri,  2 Sep 2022 18:48:58 +0300
From:   Abel Vesa <abel.vesa@...aro.org>
To:     Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        Amol Maheshwari <amahesh@....qualcomm.com>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...ainline.org>,
        Ekansh Gupta <quic_ekagupt@...cinc.com>
Cc:     Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-arm-msm@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        devicetree@...r.kernel.org
Subject: [PATCH v2 08/10] misc: fastrpc: Safekeep mmaps on interrupted invoke

If the userspace daemon is killed in the middle of an invoke (e.g.
audiopd listerner invoke), we need to skip the unmapping on device
release, otherwise the DSP will crash. So lets safekeep all the maps
only if there is in invoke interrupted, by attaching them to the channel
context (which is resident until RPMSG driver is removed), and restore
them back to the fastrpc user on the next device open call.

Signed-off-by: Abel Vesa <abel.vesa@...aro.org>
---
 drivers/misc/fastrpc.c | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
index 2c656da4ca5e..41eabdf0a256 100644
--- a/drivers/misc/fastrpc.c
+++ b/drivers/misc/fastrpc.c
@@ -275,6 +275,7 @@ struct fastrpc_channel_ctx {
 	struct fastrpc_device *secure_fdevice;
 	struct fastrpc_device *fdevice;
 	struct fastrpc_buf *remote_heap;
+	struct list_head invoke_interrupted_mmaps;
 	bool secure;
 	bool unsigned_support;
 };
@@ -1114,6 +1115,26 @@ static int fastrpc_invoke_send(struct fastrpc_session_ctx *sctx,
 
 }
 
+static void fastrpc_invoke_interrupted_restore_mmaps(struct fastrpc_user *fl)
+{
+	struct fastrpc_buf *buf, *b;
+
+	list_for_each_entry_safe(buf, b, &fl->cctx->invoke_interrupted_mmaps, node) {
+		list_del(&buf->node);
+		list_add(&buf->node, &fl->mmaps);
+	}
+}
+
+static void fastrpc_invoke_interrupted_save_mmaps(struct fastrpc_user *fl)
+{
+	struct fastrpc_buf *buf, *b;
+
+	list_for_each_entry_safe(buf, b, &fl->mmaps, node) {
+		list_del(&buf->node);
+		list_add_tail(&buf->node, &fl->cctx->invoke_interrupted_mmaps);
+	}
+}
+
 static int fastrpc_internal_invoke(struct fastrpc_user *fl,  u32 kernel,
 				   u32 handle, u32 sc,
 				   struct fastrpc_invoke_args *args)
@@ -1182,6 +1203,9 @@ static int fastrpc_internal_invoke(struct fastrpc_user *fl,  u32 kernel,
 		fastrpc_context_put(ctx);
 	}
 
+	if (err == -ERESTARTSYS)
+		fastrpc_invoke_interrupted_save_mmaps(fl);
+
 	if (err)
 		dev_dbg(fl->sctx->dev, "Error: Invoke Failed %d\n", err);
 
@@ -1551,6 +1575,8 @@ static int fastrpc_device_open(struct inode *inode, struct file *filp)
 		return -EBUSY;
 	}
 
+	fastrpc_invoke_interrupted_restore_mmaps(fl);
+
 	spin_lock_irqsave(&cctx->lock, flags);
 	list_add_tail(&fl->user, &cctx->users);
 	spin_unlock_irqrestore(&cctx->lock, flags);
@@ -2268,6 +2294,7 @@ static int fastrpc_rpmsg_probe(struct rpmsg_device *rpdev)
 	dev_set_drvdata(&rpdev->dev, data);
 	dma_set_mask_and_coherent(rdev, DMA_BIT_MASK(32));
 	INIT_LIST_HEAD(&data->users);
+	INIT_LIST_HEAD(&data->invoke_interrupted_mmaps);
 	spin_lock_init(&data->lock);
 	idr_init(&data->ctx_idr);
 	data->domain_id = domain_id;
@@ -2292,6 +2319,7 @@ static void fastrpc_notify_users(struct fastrpc_user *user)
 static void fastrpc_rpmsg_remove(struct rpmsg_device *rpdev)
 {
 	struct fastrpc_channel_ctx *cctx = dev_get_drvdata(&rpdev->dev);
+	struct fastrpc_buf *buf, *b;
 	struct fastrpc_user *user;
 	unsigned long flags;
 
@@ -2306,6 +2334,9 @@ static void fastrpc_rpmsg_remove(struct rpmsg_device *rpdev)
 	if (cctx->secure_fdevice)
 		misc_deregister(&cctx->secure_fdevice->miscdev);
 
+	list_for_each_entry_safe(buf, b, &cctx->invoke_interrupted_mmaps, node)
+		list_del(&buf->node);
+
 	if (cctx->remote_heap)
 		fastrpc_buf_free(cctx->remote_heap);
 
-- 
2.34.1