File xen.d25cc3ec93ebda030349045d2c7fa14ffde07ed7.patch of Package xen

Overview Repositories Revisions Requests Users Attributes Meta

File xen.d25cc3ec93ebda030349045d2c7fa14ffde07ed7.patch of Package xen (Revision 14fcb29724a0b7c2d84e1ce1504b42fb)

Currently displaying revision 14fcb29724a0b7c2d84e1ce1504b42fb , Show latest

From: =?UTF-8?q?Marek=20Marczykowski-G=C3=B3recki?=
 <marmarek@invisiblethingslab.com>
Date: Wed, 19 Aug 2020 04:00:35 +0200
Subject: d25cc3ec93ebda030349045d2c7fa14ffde07ed7
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

libxl: workaround gcc 10.2 maybe-uninitialized warning

It seems xlu_pci_parse_bdf has a state machine that is too complex for
gcc to understand. The build fails with:

libxlu_pci.c: In function 'xlu_pci_parse_bdf':
    libxlu_pci.c:32:18: error: 'func' may be used uninitialized in this function [-Werror=maybe-uninitialized]
       32 |     pcidev->func = func;
          |     ~~~~~~~~~~~~~^~~~~~
    libxlu_pci.c:51:29: note: 'func' was declared here
       51 |     unsigned dom, bus, dev, func, vslot = 0;
          |                             ^~~~
    libxlu_pci.c:31:17: error: 'dev' may be used uninitialized in this function [-Werror=maybe-uninitialized]
       31 |     pcidev->dev = dev;
          |     ~~~~~~~~~~~~^~~~~
    libxlu_pci.c:51:24: note: 'dev' was declared here
       51 |     unsigned dom, bus, dev, func, vslot = 0;
          |                        ^~~
    libxlu_pci.c:30:17: error: 'bus' may be used uninitialized in this function [-Werror=maybe-uninitialized]
       30 |     pcidev->bus = bus;
          |     ~~~~~~~~~~~~^~~~~
    libxlu_pci.c:51:19: note: 'bus' was declared here
       51 |     unsigned dom, bus, dev, func, vslot = 0;
          |                   ^~~
    libxlu_pci.c:29:20: error: 'dom' may be used uninitialized in this function [-Werror=maybe-uninitialized]
       29 |     pcidev->domain = domain;
          |     ~~~~~~~~~~~~~~~^~~~~~~~
    libxlu_pci.c:51:14: note: 'dom' was declared here
       51 |     unsigned dom, bus, dev, func, vslot = 0;
          |              ^~~
    cc1: all warnings being treated as errors

Workaround it by setting the initial value to invalid value (0xffffffff)
and then assert on each value being set. This way we mute the gcc
warning, while still detecting bugs in the parse code.

Signed-off-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Reviewed-by: Ian Jackson <ian.jackson@eu.citrix.com>
---
 tools/libxl/libxlu_pci.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/tools/libxl/libxlu_pci.c
+++ b/tools/libxl/libxlu_pci.c
@@ -36,28 +36,29 @@ static int pcidev_struct_fill(libxl_device_pci *pcidev, unsigned int domain,
 
 #define STATE_DOMAIN    0
 #define STATE_BUS       1
 #define STATE_DEV       2
 #define STATE_FUNC      3
 #define STATE_VSLOT     4
 #define STATE_OPTIONS_K 6
 #define STATE_OPTIONS_V 7
 #define STATE_TERMINAL  8
 #define STATE_TYPE      9
 #define STATE_RDM_STRATEGY      10
 #define STATE_RESERVE_POLICY    11
+#define INVALID         0xffffffff
 int xlu_pci_parse_bdf(XLU_Config *cfg, libxl_device_pci *pcidev, const char *str)
 {
     unsigned state = STATE_DOMAIN;
-    unsigned dom, bus, dev, func, vslot = 0;
+    unsigned dom = INVALID, bus = INVALID, dev = INVALID, func = INVALID, vslot = 0;
     char *buf2, *tok, *ptr, *end, *optkey = NULL;
 
     if ( NULL == (buf2 = ptr = strdup(str)) )
         return ERROR_NOMEM;
 
     for(tok = ptr, end = ptr + strlen(ptr) + 1; ptr < end; ptr++) {
         switch(state) {
         case STATE_DOMAIN:
             if ( *ptr == ':' ) {
                 state = STATE_BUS;
                 *ptr = '\0';
                 if ( hex_convert(tok, &dom, 0xffff) )
@@ -161,24 +162,26 @@ int xlu_pci_parse_bdf(XLU_Config *cfg, libxl_device_pci *pcidev, const char *str
                     XLU__PCI_ERR(cfg, "Unknown PCI BDF option: %s", optkey);
                 }
                 tok = ptr + 1;
             }
         default:
             break;
         }
     }
 
     if ( tok != ptr || state != STATE_TERMINAL )
         goto parse_error;
 
+    assert(dom != INVALID && bus != INVALID && dev != INVALID && func != INVALID);
+
     /* Just a pretty way to fill in the values */
     pcidev_struct_fill(pcidev, dom, bus, dev, func, vslot << 3);
 
     free(buf2);
 
     return 0;
 
 parse_error:
     free(buf2);
     return ERROR_INVAL;
 }

Places

File xen.d25cc3ec93ebda030349045d2c7fa14ffde07ed7.patch of Package xen (Revision 14fcb29724a0b7c2d84e1ce1504b42fb)

Places