FAILED: patch "[PATCH] xhci: Do not use GFP_KERNEL in (potentially) atomic context" failed to apply to 4.9-stable tree

[<gregkh@xxxxxxxxxxxxxxxxxxx>]

The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

>From dda32c00c9a0fa103b5d54ef72c477b7aa993679 Mon Sep 17 00:00:00 2001
From: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>
Date: Wed, 12 May 2021 11:08:14 +0300
Subject: [PATCH] xhci: Do not use GFP_KERNEL in (potentially) atomic context

'xhci_urb_enqueue()' is passed a 'mem_flags' argument, because "URBs may be
submitted in interrupt context" (see comment related to 'usb_submit_urb()'
in 'drivers/usb/core/urb.c')

So this flag should be used in all the calling chain.
Up to now, 'xhci_check_maxpacket()' which is only called from
'xhci_urb_enqueue()', uses GFP_KERNEL.

Be safe and pass the mem_flags to this function as well.

Fixes: ddba5cd0aeff ("xhci: Use command structures when queuing commands on the command ring")
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>
Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20210512080816.866037-4-mathias.nyman@xxxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index ca9385d22f68..27283654ca08 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -1514,7 +1514,7 @@ static int xhci_configure_endpoint(struct xhci_hcd *xhci,
  * we need to issue an evaluate context command and wait on it.
  */
 static int xhci_check_maxpacket(struct xhci_hcd *xhci, unsigned int slot_id,
-		unsigned int ep_index, struct urb *urb)
+		unsigned int ep_index, struct urb *urb, gfp_t mem_flags)
 {
 	struct xhci_container_ctx *out_ctx;
 	struct xhci_input_control_ctx *ctrl_ctx;
@@ -1545,7 +1545,7 @@ static int xhci_check_maxpacket(struct xhci_hcd *xhci, unsigned int slot_id,
 		 * changes max packet sizes.
 		 */
 
-		command = xhci_alloc_command(xhci, true, GFP_KERNEL);
+		command = xhci_alloc_command(xhci, true, mem_flags);
 		if (!command)
 			return -ENOMEM;
 
@@ -1639,7 +1639,7 @@ static int xhci_urb_enqueue(struct usb_hcd *hcd, struct urb *urb, gfp_t mem_flag
 		 */
 		if (urb->dev->speed == USB_SPEED_FULL) {
 			ret = xhci_check_maxpacket(xhci, slot_id,
-					ep_index, urb);
+					ep_index, urb, mem_flags);
 			if (ret < 0) {
 				xhci_urb_free_priv(urb_priv);
 				urb->hcpriv = NULL;