| Message ID | 20200220062315.69253-1-keescook@chromium.org (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | usb: gadget: net2280: Distribute switch variables for initialization | expand |
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@chromium.org> > --- > 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): > > >
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; - + } case USB_REQ_CLEAR_FEATURE: switch (r.bRequestType) { case (USB_DIR_OUT | USB_TYPE_STANDARD | USB_RECIP_DEVICE):
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@chromium.org> --- drivers/usb/gadget/udc/net2280.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-)