From d25cc3ec93ebda030349045d2c7fa14ffde07ed7 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Marek=20Marczykowski-G=C3=B3recki?= Date: Wed, 19 Aug 2020 04:00:35 +0200 Subject: [PATCH] libxl: workaround gcc 10.2 maybe-uninitialized warning MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 Reviewed-by: Ian Jackson --- tools/libxl/libxlu_pci.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/tools/libxl/libxlu_pci.c b/tools/libxl/libxlu_pci.c index 7947687661..e2709c5f89 100644 --- a/tools/libxl/libxlu_pci.c +++ b/tools/libxl/libxlu_pci.c @@ -45,10 +45,11 @@ static int pcidev_struct_fill(libxl_device_pci *pcidev, unsigned int domain, #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)) ) @@ -170,6 +171,8 @@ int xlu_pci_parse_bdf(XLU_Config *cfg, libxl_device_pci *pcidev, const char *str 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); -- 2.39.5