USB: xhci: Allow allocation of commands without input contexts.

The xhci_command structure is the basic structure for issuing commands to
the xHCI hardware.  It contains a struct completion (so that the issuing
function can wait on the command), command status, and a input context
that is used to pass information to the hardware.  Not all commands need
the input context, so make it optional to allocate.  Allow
xhci_free_container_ctx() to be passed a NULL input context, to make
freeing the xhci_command structure simple.

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/host/xhci-hcd.c

@@ -1679,7 +1679,7 @@ int xhci_update_hub_device(struct usb_hcd *hcd, struct usb_device *hdev,
 		xhci_warn(xhci, "Cannot update hub desc for unknown device.\n");
 		return -EINVAL;
 	}
-	config_cmd = xhci_alloc_command(xhci, true, mem_flags);
+	config_cmd = xhci_alloc_command(xhci, true, true, mem_flags);
 	if (!config_cmd) {
 		xhci_dbg(xhci, "Could not allocate xHCI command structure.\n");
 		return -ENOMEM;

drivers/usb/host/xhci-mem.c

@@ -267,6 +267,8 @@ struct xhci_container_ctx *xhci_alloc_container_ctx(struct xhci_hcd *xhci,
 void xhci_free_container_ctx(struct xhci_hcd *xhci,
 			     struct xhci_container_ctx *ctx)
 {
+	if (!ctx)
+		return;
 	dma_pool_free(xhci->device_pool, ctx->bytes, ctx->dma);
 	kfree(ctx);
 }
@@ -844,7 +846,8 @@ static void scratchpad_free(struct xhci_hcd *xhci)
 }
 
 struct xhci_command *xhci_alloc_command(struct xhci_hcd *xhci,
-		bool allocate_completion, gfp_t mem_flags)
+		bool allocate_in_ctx, bool allocate_completion,
+		gfp_t mem_flags)
 {
 	struct xhci_command *command;
 
@@ -852,11 +855,14 @@ struct xhci_command *xhci_alloc_command(struct xhci_hcd *xhci,
 	if (!command)
 		return NULL;
 
-	command->in_ctx =
-		xhci_alloc_container_ctx(xhci, XHCI_CTX_TYPE_INPUT, mem_flags);
-	if (!command->in_ctx) {
-		kfree(command);
-		return NULL;
+	if (allocate_in_ctx) {
+		command->in_ctx =
+			xhci_alloc_container_ctx(xhci, XHCI_CTX_TYPE_INPUT,
+					mem_flags);
+		if (!command->in_ctx) {
+			kfree(command);
+			return NULL;
+		}
 	}
 
 	if (allocate_completion) {

drivers/usb/host/xhci.h

@@ -1237,7 +1237,8 @@ void xhci_free_or_cache_endpoint_ring(struct xhci_hcd *xhci,
 		struct xhci_virt_device *virt_dev,
 		unsigned int ep_index);
 struct xhci_command *xhci_alloc_command(struct xhci_hcd *xhci,
-		bool allocate_completion, gfp_t mem_flags);
+		bool allocate_in_ctx, bool allocate_completion,
+		gfp_t mem_flags);
 void xhci_free_command(struct xhci_hcd *xhci,
 		struct xhci_command *command);