From: Michael Brown <mcb30@ipxe.org>
Date: Sun, 3 Jan 2021 19:08:49 +0000 (+0000)
Subject: [xhci] Fail attempts to issue concurrent commands
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=017b345d5a3c9ba8cc10e2ca69b6c986b91e0668;p=thirdparty%2Fipxe.git

[xhci] Fail attempts to issue concurrent commands

The xHCI driver can handle only a single command TRB in progress at
any one time.  Immediately fail any attempts to issue concurrent
commands (which should not occur in normal operation).

Signed-off-by: Michael Brown <mcb30@ipxe.org>
---

diff --git a/src/drivers/usb/xhci.c b/src/drivers/usb/xhci.c
index 7bc2e356e..7c8b2f21c 100644
--- a/src/drivers/usb/xhci.c
+++ b/src/drivers/usb/xhci.c
@@ -1813,6 +1813,13 @@ static int xhci_command ( struct xhci_device *xhci, union xhci_trb *trb ) {
 	unsigned int i;
 	int rc;
 
+	/* Sanity check */
+	if ( xhci->pending != NULL ) {
+		DBGC ( xhci, "XHCI %s command ring busy\n", xhci->name );
+		rc = -EBUSY;
+		goto err_pending;
+	}
+
 	/* Record the pending command */
 	xhci->pending = trb;
 
@@ -1855,6 +1862,7 @@ static int xhci_command ( struct xhci_device *xhci, union xhci_trb *trb ) {
 
  err_enqueue:
 	xhci->pending = NULL;
+ err_pending:
 	return rc;
 }