[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v9 06/13] x86: dynamically get/set CBM for a domain
>>> On 23.06.15 at 11:03, <chao.p.peng@xxxxxxxxxxxxxxx> wrote: > On Tue, Jun 23, 2015 at 09:35:30AM +0100, Jan Beulich wrote: >> >>> On 23.06.15 at 09:19, <chao.p.peng@xxxxxxxxxxxxxxx> wrote: >> > On Tue, Jun 16, 2015 at 08:08:34AM +0100, Jan Beulich wrote: >> >> >>> On 03.06.15 at 06:53, <chao.p.peng@xxxxxxxxxxxxxxx> wrote: >> >> > +int psr_set_l3_cbm(struct domain *d, unsigned int socket, uint64_t cbm) >> >> > +{ >> >> > + unsigned int old_cos, cos; >> >> > + struct psr_cat_cbm *map, *found = NULL; >> >> > + struct psr_cat_socket_info *info = NULL; >> >> > + int ret = get_cat_socket_info(socket, &info); >> >> > + >> >> > + if ( ret ) >> >> > + return ret; >> >> > + >> >> > + if ( !psr_check_cbm(info->cbm_len, cbm) ) >> >> > + return -EINVAL; >> >> > + >> >> > + old_cos = d->arch.psr_cos_ids[socket]; >> >> > + map = info->cos_to_cbm; >> >> > + >> >> > + spin_lock(&info->cbm_lock); >> >> > + >> >> > + for ( cos = 0; cos <= info->cos_max; cos++ ) >> >> > + { >> >> > + /* If still not found, then keep unused one. */ >> >> > + if ( !found && cos != 0 && map[cos].ref == 0 ) >> >> > + found = map + cos; >> >> > + else if ( map[cos].cbm == cbm ) >> >> > + { >> >> > + if ( unlikely(cos == old_cos) ) >> >> > + { >> >> > + spin_unlock(&info->cbm_lock); >> >> > + return 0; >> >> >> >> Is this in particular, but also the surrounding "else if", correct when >> >> map[cos].ref == 0? >> > >> > I can't see any problem now. >> >> Further down in the function you increment found->ref, and it looks >> suspicious that you return success here having found a slot possibly >> having refount zero (and thus available for re-use for another CBM). > > In such case 'cos == old_cos' can't be true, otherwise refcount can't be > zero. > >> I.e. if this indeed is intended and correct, I think this needs to be >> explained in a brief comment. > > So yes, I can leave a comment here. Or maybe even better a respective ASSERT(). Jan _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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