[PATCH v1 4/5] misc: fastrpc: Add support to save and restore interrupted

[Ekansh Gupta]

For any remote call, driver sends a message to DSP using RPMSG
framework. After message is sent, there is a wait on a completion
object at driver which is completed when DSP response is received.

There is a possibility that a signal is received while waiting
causing the wait function to return -ERESTARTSYS. In this case
the context should be saved and it should get restored for the
next invocation for the thread.

Adding changes to support saving and restoring of interrupted
fastrpc contexts.

Signed-off-by: Ekansh Gupta <quic_ekangupt@xxxxxxxxxxx>
---
 drivers/misc/fastrpc.c | 76 +++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 72 insertions(+), 4 deletions(-)

diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
index f8c1c381..1b26718 100644
--- a/drivers/misc/fastrpc.c
+++ b/drivers/misc/fastrpc.c
@@ -332,6 +332,7 @@ struct fastrpc_user {
 	struct list_head user;
 	struct list_head maps;
 	struct list_head pending;
+	struct list_head interrupted;
 	struct list_head mmaps;
 
 	struct fastrpc_channel_ctx *cctx;
@@ -711,6 +712,40 @@ static struct fastrpc_invoke_ctx *fastrpc_context_alloc(
 	return ERR_PTR(ret);
 }
 
+static struct fastrpc_invoke_ctx *fastrpc_context_restore_interrupted(
+			struct fastrpc_user *fl, struct fastrpc_invoke *inv)
+{
+	struct fastrpc_invoke_ctx *ctx = NULL, *ictx = NULL, *n;
+
+	spin_lock(&fl->lock);
+	list_for_each_entry_safe(ictx, n, &fl->interrupted, node) {
+		if (ictx->pid == current->pid) {
+			if (inv->sc != ictx->sc || ictx->fl != fl) {
+				dev_err(ictx->fl->sctx->dev,
+					"interrupted sc (0x%x) or fl (%pK) does not match with invoke sc (0x%x) or fl (%pK)\n",
+					ictx->sc, ictx->fl, inv->sc, fl);
+				spin_unlock(&fl->lock);
+				return ERR_PTR(-EINVAL);
+			}
+			ctx = ictx;
+			list_del(&ctx->node);
+			list_add_tail(&ctx->node, &fl->pending);
+			break;
+		}
+	}
+	spin_unlock(&fl->lock);
+	return ctx;
+}
+
+static void fastrpc_context_save_interrupted(
+			struct fastrpc_invoke_ctx *ctx)
+{
+	spin_lock(&ctx->fl->lock);
+	list_del(&ctx->node);
+	list_add_tail(&ctx->node, &ctx->fl->interrupted);
+	spin_unlock(&ctx->fl->lock);
+}
+
 static struct sg_table *
 fastrpc_map_dma_buf(struct dma_buf_attachment *attachment,
 		    enum dma_data_direction dir)
@@ -1261,6 +1296,14 @@ static int fastrpc_internal_invoke(struct fastrpc_user *fl,  u32 kernel,
 		return -EPERM;
 	}
 
+	if (!kernel) {
+		ctx = fastrpc_context_restore_interrupted(fl, inv);
+		if (IS_ERR(ctx))
+			return PTR_ERR(ctx);
+		if (ctx)
+			goto wait;
+	}
+
 	ctx = fastrpc_context_alloc(fl, kernel, sc, invoke);
 	if (IS_ERR(ctx))
 		return PTR_ERR(ctx);
@@ -1284,6 +1327,7 @@ static int fastrpc_internal_invoke(struct fastrpc_user *fl,  u32 kernel,
 		goto bail;
 	PERF_END);
 
+wait:
 	if (kernel) {
 		if (!wait_for_completion_timeout(&ctx->work, 10 * HZ))
 			err = -ETIMEDOUT;
@@ -1320,6 +1364,9 @@ static int fastrpc_internal_invoke(struct fastrpc_user *fl,  u32 kernel,
 	}
 
 	if (err == -ERESTARTSYS) {
+		if (ctx)
+			fastrpc_context_save_interrupted(ctx);
+
 		list_for_each_entry_safe(buf, b, &fl->mmaps, node) {
 			list_del(&buf->node);
 			list_add_tail(&buf->node, &fl->cctx->invoke_interrupted_mmaps);
@@ -1620,6 +1667,25 @@ static void fastrpc_session_free(struct fastrpc_channel_ctx *cctx,
 	spin_unlock_irqrestore(&cctx->lock, flags);
 }
 
+static void fastrpc_context_list_free(struct fastrpc_user *fl)
+{
+	struct fastrpc_invoke_ctx *ctx, *n;
+
+	list_for_each_entry_safe(ctx, n, &fl->interrupted, node) {
+		spin_lock(&fl->lock);
+		list_del(&ctx->node);
+		spin_unlock(&fl->lock);
+		fastrpc_context_put(ctx);
+	}
+
+	list_for_each_entry_safe(ctx, n, &fl->pending, node) {
+		spin_lock(&fl->lock);
+		list_del(&ctx->node);
+		spin_unlock(&fl->lock);
+		fastrpc_context_put(ctx);
+	}
+}
+
 static int fastrpc_release_current_dsp_process(struct fastrpc_user *fl)
 {
 	struct fastrpc_invoke_args args[1];
@@ -1656,10 +1722,7 @@ static int fastrpc_device_release(struct inode *inode, struct file *file)
 	if (fl->init_mem)
 		fastrpc_buf_free(fl->init_mem);
 
-	list_for_each_entry_safe(ctx, n, &fl->pending, node) {
-		list_del(&ctx->node);
-		fastrpc_context_put(ctx);
-	}
+	fastrpc_context_list_free(fl);
 
 	list_for_each_entry_safe(map, m, &fl->maps, node)
 		fastrpc_map_put(map);
@@ -1700,6 +1763,7 @@ static int fastrpc_device_open(struct inode *inode, struct file *filp)
 	spin_lock_init(&fl->lock);
 	mutex_init(&fl->mutex);
 	INIT_LIST_HEAD(&fl->pending);
+	INIT_LIST_HEAD(&fl->interrupted);
 	INIT_LIST_HEAD(&fl->maps);
 	INIT_LIST_HEAD(&fl->mmaps);
 	INIT_LIST_HEAD(&fl->user);
@@ -2555,6 +2619,10 @@ static void fastrpc_notify_users(struct fastrpc_user *user)
 		ctx->retval = -EPIPE;
 		complete(&ctx->work);
 	}
+	list_for_each_entry(ctx, &user->interrupted, node) {
+		ctx->retval = -EPIPE;
+		complete(&ctx->work);
+	}
 	spin_unlock(&user->lock);
 }
 
-- 
2.7.4