On Mon, Sep 9, 2013 at 10:17 PM, Konstantin Belousov <k...@freebsd.org>wrote:
> Author: kib > Date: Tue Sep 10 05:17:53 2013 > New Revision: 255439 > URL: http://svnweb.freebsd.org/changeset/base/255439 > > Log: > Call free() on the pointer returned from malloc(). > > Reported and tested by: Oliver Pinter <oliver.p...@gmail.com> > Sponsored by: The FreeBSD Foundation > MFC after: 3 days > Approved by: re (delphij) > > Modified: > head/sys/dev/cpuctl/cpuctl.c > > Modified: head/sys/dev/cpuctl/cpuctl.c > > ============================================================================== > --- head/sys/dev/cpuctl/cpuctl.c Tue Sep 10 03:48:18 2013 > (r255438) > +++ head/sys/dev/cpuctl/cpuctl.c Tue Sep 10 05:17:53 2013 > (r255439) > @@ -295,10 +295,10 @@ cpuctl_do_update(int cpu, cpuctl_update_ > static int > update_intel(int cpu, cpuctl_update_args_t *args, struct thread *td) > { > - void *ptr = NULL; > + void *ptr; > uint64_t rev0, rev1; > uint32_t tmp[4]; > - int is_bound = 0; > + int is_bound; > int oldcpu; > int ret; > > @@ -312,10 +312,11 @@ update_intel(int cpu, cpuctl_update_args > } > > /* > - * 16 byte alignment required. > + * 16 byte alignment required. Rely on the fact that > + * malloc(9) always returns the pointer aligned at least on > + * the size of the allocation. > */ > ptr = malloc(args->size + 16, M_CPUCTL, M_WAITOK); > - ptr = (void *)(16 + ((intptr_t)ptr & ~0xf)); > if (copyin(args->data, ptr, args->size) != 0) { > DPRINTF("[cpuctl,%d]: copyin %p->%p of %zd bytes failed", > __LINE__, args->data, ptr, args->size); > @@ -408,10 +409,10 @@ fail: > static int > update_via(int cpu, cpuctl_update_args_t *args, struct thread *td) > { > - void *ptr = NULL; > + void *ptr; > uint64_t rev0, rev1, res; > uint32_t tmp[4]; > - int is_bound = 0; > + int is_bound; > int oldcpu; > int ret; > > @@ -427,8 +428,7 @@ update_via(int cpu, cpuctl_update_args_t > /* > * 4 byte alignment required. > */ > - ptr = malloc(args->size + 16, M_CPUCTL, M_WAITOK); > - ptr = (void *)(16 + ((intptr_t)ptr & ~0xf)); > + ptr = malloc(args->size, M_CPUCTL, M_WAITOK); > if (copyin(args->data, ptr, args->size) != 0) { > DPRINTF("[cpuctl,%d]: copyin %p->%p of %zd bytes failed", > __LINE__, args->data, ptr, args->size); > I don't know exactly what the stock malloc(9) will return, but memguard(9), under its default mode with vm.memguard.options having MG_GUARD_AROUND set will align the returned pointer to only 16 bytes. When I added that feature I almost made it 8 bytes, but I think I saw that uma(9) had a 16-byte alignment so I preserved that. I.e., this code does still work with malloc(9) and memguard(9). But why does this need 16 byte alignment? Especially when one of the comments says 4-byte alignment? Thanks, matthew _______________________________________________ svn-src-all@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
