[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 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. Chao _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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