Messages in this thread | | | Date | Wed, 26 Dec 2007 17:49:55 -0800 | From | "H. Peter Anvin" <> | Subject | Re: [PATCH 1/3] arch/x86: Use offsetof |
| |
Jan Engelhardt wrote: > On Dec 26 2007 17:01, H. Peter Anvin wrote: >>>> @@ -215,7 +215,9 @@ asmlinkage int sys_vm86old(struct pt_reg >>>> ret = -EFAULT; >>>> if (tmp) >>>> goto out; >>>> - memset(&info.vm86plus, 0, (int)&info.regs32 - (int)&info.vm86plus); >>>> + memset(&info.vm86plus, 0, >>>> + offsetof(struct kernel_vm86_struct, regs32) - >>>> + offsetof(struct kernel_vm86_struct, vm86plus)); >>> I do not think this makes it more readable... (int) -> (char *) would >>> make it portable and readable, AFAICT. >>> Pavel >> The right way to do it is: >> >> memset(&info.vm86plus, 0, sizeof info.vm86plus); > > Either way, downcasting a pointer to (int) is dangerous, > even if this one occurrence happens to be in 32-bit-only code.
Actually, it would be safe (although stupid) in this case since the difference would still be 32 bits or less.
Doesn't make it any less wrong.
-hpa
| |