On 12/10/2016 09:54, Gonglei (Arei) wrote: > >> -----Original Message----- >> From: Paolo Bonzini [mailto:paolo.bonz...@gmail.com] On Behalf Of Paolo >> Bonzini >> Sent: Wednesday, October 12, 2016 3:41 PM >> To: Gonglei (Arei); Michael Tokarev; qemu-devel@nongnu.org >> Cc: qemu-triv...@nongnu.org; Herongguang (Stephen) >> Subject: Re: [PATCH] mmap-alloc: check before use for ptr pointer >> >> >> >> On 12/10/2016 09:37, Gonglei (Arei) wrote: >>>> -----Original Message----- >>>> From: Michael Tokarev [mailto:m...@tls.msk.ru] >>>> Sent: Wednesday, October 12, 2016 2:46 PM >>>> Subject: Re: [PATCH] mmap-alloc: check before use for ptr pointer >>>> >>>> 12.10.2016 05:05, Gonglei wrote: >>>>> If ptr mmap failed, we don't need to do a superfluous >>>>> calculation for offset variable by ptr (MAP_FAILED). >>>> >>>> What's the point? There's no problem in extra calculation >>>> if mmap failed, yes, but do we really care? As of it is now, >>>> it is more compact and readable, and works. I think. >>>> >>> >>> I just think it's more reasonable because the ptr is checked after >>> used. Why do we need a extra calculation? >> >> Another reasonable objection (that however your patch doesn't fix) is >> that align is being used before the assertion: >> >> assert(!(align & (align - 1))); >> > > Eh, align is used at the beginning of the qemu_ram_mmap() ;)
Yes, but the assertion is there because align is passed to QEMU_ALIGN_UP. Paolo
