On Wed, Oct 16, 2019 at 07:23:08PM +0300, Andy Shevchenko wrote: > On Wed, Oct 16, 2019 at 07:18:45PM +0300, Andy Shevchenko wrote: > > On Wed, Oct 16, 2019 at 09:01:26AM -0700, Dmitry Torokhov wrote: > > > On Wed, Oct 16, 2019 at 10:48:57AM +0300, Andy Shevchenko wrote: > > > > On Tue, Oct 15, 2019 at 11:25:53AM -0700, Dmitry Torokhov wrote: > > > > > > You store a value as union, but going to read as a member of union? > > > > I'm pretty sure it breaks standard rules. > > > > > > No, I move the values _in place_ of the union, and the data is always > > > fetched via void pointers. And copying data via char * or memcpy() is > > > allowed even in C99 and C11. > > > > > > But I am wondering why are we actually worrying about all of this? The > > > kernel is gnu89 and I think is going to stay this way because we use > > > initializers with a cast in a lot of places: > > > > > > #define __RAW_SPIN_LOCK_UNLOCKED(lockname) \ > > > (raw_spinlock_t) __RAW_SPIN_LOCK_INITIALIZER(lockname) > > > > > > and C99 and gnu99 do not allow this. See > > > https://lore.kernel.org/lkml/20141019231031.GB9319@xxxxxxxxxxxxxxxxx/ > > > > This is simple not a cast. > > 4.62 Compound literals in C99 > ISO C99 supports compound literals. A compound literal looks like a cast > followed by an initializer. Its value is an object of the type specified in the > cast, containing the elements specified in the initializer. It is an lvalue. Yes, these are compound literals. And they can not be used as initializers: https://lore.kernel.org/lkml/CAHk-=wgXBV57mz46ZB5XivjiSBGkM0cjuvnU2OWyfRF=+41NPQ@xxxxxxxxxxxxxx/ Thanks. -- Dmitry
