On Monday 09 November 2015 22:53:17 Timur Tabi wrote: > Sinan Kaya wrote: > > > > The code says it is using these macros for small integers only which > > can't overflow. I was trying to get rid of compiler warning and it seems > > to have disappeared. > > I would double-check the assembly code, if I were you. I don't like it > when warnings just go away like that. > > Besides, we *should* be using do_div() for 64-bit division. I stared at this code for some time and couldn't figure out whether it is actually safe or not. The point here is that it doesn't actually do a 64-bit division here: MULDIV(INT_MAX, USER_HZ, HZ) where all arguments are 32bit and it tries to figure out whether the ioctl argument is too big to fit into a 32-bit number but it does a 'long' division that happens to be 64-bit long on architectures with the respective register size when it then does sfp->timeout = MULDIV (val, HZ, USER_HZ); to scale up the argument from USER_HZ to the possibly larger in-kernel HZ value. So I think it's safe as is, but I'm still not entirely sure. Arnd -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
