[Qemu-devel] [PATCH 4/4] xhci: guard xhci_kick_epctx against recursive calls

[Gerd Hoffmann <kraxel@redhat.com>]

Track xhci_kick_epctx processing being active in a variable.  Check the
variable before calling xhci_kick_epctx from xhci_kick_ep.  Add an
assert to make sure we don't call recursively into xhci_kick_epctx.

Cc: 1653384@bugs.launchpad.net
Fixes: 94b037f2a451b3dc855f9f2c346e5049a361bd55
Reported-by: Fabian Lesniak <fabian@lesniak-it.de>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 hw/usb/hcd-xhci.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/hw/usb/hcd-xhci.c b/hw/usb/hcd-xhci.c
index 899a410..12cac89 100644
--- a/hw/usb/hcd-xhci.c
+++ b/hw/usb/hcd-xhci.c
@@ -390,6 +390,7 @@ struct XHCIEPContext {
     dma_addr_t pctx;
     unsigned int max_psize;
     uint32_t state;
+    uint32_t kick_active;
 
     /* streams */
     unsigned int max_pstreams;
@@ -2131,6 +2132,9 @@ static void xhci_kick_ep(XHCIState *xhci, unsigned int slotid,
         return;
     }
 
+    if (!epctx->kick_active) {
+        return;
+    }
     xhci_kick_epctx(epctx, streamid);
 }
 
@@ -2155,6 +2159,9 @@ static void xhci_kick_epctx(XHCIEPContext *epctx, unsigned int streamid)
         return;
     }
 
+    assert(!epctx->kick_active);
+    epctx->kick_active++;
+
     if (epctx->retry) {
         XHCITransfer *xfer = epctx->retry;
 
@@ -2253,6 +2260,7 @@ static void xhci_kick_epctx(XHCIEPContext *epctx, unsigned int streamid)
             break;
         }
     }
+    epctx->kick_active--;
 
     ep = xhci_epid_to_usbep(epctx);
     if (ep) {
-- 
1.8.3.1