Re: [PATCH 1/2] dev-core: fix build break when DEBUG is enabled

On 15/08/13 19:37, Greg KH wrote:

On Thu, Aug 15, 2013 at 07:04:54PM +0300, Dmitry Kasatkin wrote:

quoted

When DEBUG is defined, dev_dbg_ratelimited uses dynamic debug data
structures even when CONFIG_DYNAMIC_DEBUG is not defined.
It leads to build break.
For example, when I try to use dev_dbg_ratelimited in USB code and
CONFIG_USB_DEBUG is enabled, but CONFIG_DYNAMIC_DEBUG is not, I get:

  CC [M]  drivers/usb/host/xhci-ring.o
  drivers/usb/host/xhci-ring.c: In function ‘xhci_queue_intr_tx’:
  drivers/usb/host/xhci-ring.c:3059:3: error: implicit declaration of function ‘DEFINE_DYNAMIC_DEBUG_METADATA’ [-Werror=implicit-function-declaration]
  drivers/usb/host/xhci-ring.c:3059:3: error: ‘descriptor’ undeclared (first use in this function)
  drivers/usb/host/xhci-ring.c:3059:3: note: each undeclared identifier is reported only once for each function it appears in
  drivers/usb/host/xhci-ring.c:3059:3: error: implicit declaration of function ‘__dynamic_pr_debug’ [-Werror=implicit-function-declaration]
  drivers/usb/host/xhci-ring.c: In function ‘xhci_queue_isoc_tx_prepare’:
  drivers/usb/host/xhci-ring.c:3847:3: error: ‘descriptor’ undeclared (first use in this function)
  cc1: some warnings being treated as errors
  make[2]: *** [drivers/usb/host/xhci-ring.o] Error 1
  make[1]: *** [drivers/usb/host] Error 2
  make: *** [drivers/usb/] Error 2

This patch separates definition for CONFIG_DYNAMIC_DEBUG and DEBUG cases.

Signed-off-by: Dmitry Kasatkin <redacted>
Cc: stable@vger.kernel.org

How is this a stable issue?  I don't see how the rules listed in
Documentation/stable_kernel_rules.txt apply here, what am I missing?

Not to say your patch isn't correct, just that it's not stable material,
right?

thanks,

greg k-h

There are few drivers which uses dev_dbg_ratelimited().
In the case someone tries to build kernel with those drivers with DEBUG
enabled and without CONFIG_DYNAMIC_DEBUG,
will get the build break. It will happen also on stable kernel.

- Dmitry