On Wed, 19 Feb 2020, Kees Cook wrote: > Variables declared in a switch statement before any case statements > cannot be automatically initialized with compiler instrumentation (as > they are not part of any execution flow). With GCC's proposed automatic > stack variable initialization feature, this triggers a warning (and they > don't get initialized). Clang's automatic stack variable initialization > (via CONFIG_INIT_STACK_ALL=y) doesn't throw a warning, but it also > doesn't initialize such variables[1]. Note that these warnings (or silent > skipping) happen before the dead-store elimination optimization phase, > so even when the automatic initializations are later elided in favor of > direct initializations, the warnings remain. > > To avoid these problems, move such variables into the "case" where > they're used or lift them up into the main function body. > > drivers/usb/gadget/udc/net2280.c: In function ‘handle_stat0_irqs_superspeed’: > drivers/usb/gadget/udc/net2280.c:2871:22: warning: statement will never be executed [-Wswitch-unreachable] > 2871 | struct net2280_ep *e; > | ^ > > [1] https://bugs.llvm.org/show_bug.cgi?id=44916 > > Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> > --- > drivers/usb/gadget/udc/net2280.c | 10 +++++----- > 1 file changed, 5 insertions(+), 5 deletions(-) > > diff --git a/drivers/usb/gadget/udc/net2280.c b/drivers/usb/gadget/udc/net2280.c > index 1fd1b9186e46..cc5869363298 100644 > --- a/drivers/usb/gadget/udc/net2280.c > +++ b/drivers/usb/gadget/udc/net2280.c > @@ -2861,6 +2861,7 @@ static void ep_clear_seqnum(struct net2280_ep *ep) > static void handle_stat0_irqs_superspeed(struct net2280 *dev, > struct net2280_ep *ep, struct usb_ctrlrequest r) > { > + struct net2280_ep *e; > int tmp = 0; > > #define w_value le16_to_cpu(r.wValue) > @@ -2868,14 +2869,13 @@ static void handle_stat0_irqs_superspeed(struct net2280 *dev, > #define w_length le16_to_cpu(r.wLength) > > switch (r.bRequest) { > - struct net2280_ep *e; > - u16 status; > - > case USB_REQ_SET_CONFIGURATION: > dev->addressed_state = !w_value; > goto usb3_delegate; > > - case USB_REQ_GET_STATUS: > + case USB_REQ_GET_STATUS: { > + u16 status; > + > switch (r.bRequestType) { > case (USB_DIR_IN | USB_TYPE_STANDARD | USB_RECIP_DEVICE): > status = dev->wakeup_enable ? 0x02 : 0x00; > @@ -2905,7 +2905,7 @@ static void handle_stat0_irqs_superspeed(struct net2280 *dev, > goto usb3_delegate; > } > break; > - > + } This is an unusual use of nested blocks (i.e., a block immediately following a "case" label, and it throws the indentation off -- there will now be two nested closing braces at the same indentation level: this one and the one preceding do_stall3:. Just define status at the function level, along with e, and don't worry about it. Alan Stern > case USB_REQ_CLEAR_FEATURE: > switch (r.bRequestType) { > case (USB_DIR_OUT | USB_TYPE_STANDARD | USB_RECIP_DEVICE): > > >
