On Fri, 27 Jan 2023 00:32:13 +0200 Vladimir Oltean wrote: > On Thu, Jan 26, 2023 at 09:15:03PM +0200, Leon Romanovsky wrote: > > From: Leon Romanovsky <leonro@xxxxxxxxxx> > > > > In netdev common pattern, xxtack pointer is forwarded to the drivers > ~~~~~~ > extack > > > to be filled with error message. However, the caller can easily > > overwrite the filled message. > > > > Instead of adding multiple "if (!extack->_msg)" checks before any > > NL_SET_ERR_MSG() call, which appears after call to the driver, let's > > add this check to common code. > > > > [1] https://lore.kernel.org/all/Y9Irgrgf3uxOjwUm@unreal > > Signed-off-by: Leon Romanovsky <leonro@xxxxxxxxxx> > > --- > > I would somewhat prefer not doing this, and instead introducing a new > NL_SET_ERR_MSG_WEAK() of sorts. That'd be my preference too, FWIW. It's only the offload cases which need this sort of fallback. BTW Vladimir, I remember us discussing this. I was searching the archive as you sent this, but can't find the thread. Mostly curious whether I flip flipped on this or I'm not completely useless :) > The reason has to do with the fact that an extack is sometimes also > used to convey warnings rather than hard errors, for example right here > in net/dsa/slave.c: > > if (err == -EOPNOTSUPP) { > if (extack && !extack->_msg) > NL_SET_ERR_MSG_MOD(extack, > "Offloading not supported"); > NL_SET_ERR_MSG_MOD(extack, > "Offloading not supported"); > err = 0; > }
