Messages in this thread Patch in this message | | | Date | Tue, 9 Jun 2015 15:28:38 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH 1/5] ipc,shm: move BUG_ON check into shm_lock |
| |
On Sat, 6 Jun 2015 06:37:56 -0700 Davidlohr Bueso <dave@stgolabs.net> wrote:
> Upon every shm_lock call, we BUG_ON if an error was returned, > indicating racing either in idr or in shm_destroy. Move this logic > into the locking. > > --- a/ipc/shm.c > +++ b/ipc/shm.c > @@ -155,8 +155,14 @@ static inline struct shmid_kernel *shm_lock(struct ipc_namespace *ns, int id) > { > struct kern_ipc_perm *ipcp = ipc_lock(&shm_ids(ns), id); > > - if (IS_ERR(ipcp)) > + if (IS_ERR(ipcp)) { > + /* > + * We raced in the idr lookup or with shm_destroy(), > + * either way, the ID is busted. > + */ > + BUG(); > return (struct shmid_kernel *)ipcp; > + }
Was there any particular reason to still do it this way? It's a bit klunky.
--- a/ipc/shm.c~ipcshm-move-bug_on-check-into-shm_lock-fix +++ a/ipc/shm.c @@ -155,14 +155,11 @@ static inline struct shmid_kernel *shm_l { struct kern_ipc_perm *ipcp = ipc_lock(&shm_ids(ns), id); - if (IS_ERR(ipcp)) { - /* - * We raced in the idr lookup or with shm_destroy(), - * either way, the ID is busted. - */ - BUG(); - return (struct shmid_kernel *)ipcp; - } + /* + * We raced in the idr lookup or with shm_destroy(). Either way, the + * ID is busted. + */ + BUG_ON(IS_ERR(ipcp)); return container_of(ipcp, struct shmid_kernel, shm_perm); } One benefit of the code you sent is that the unreachable `return' will prevent a compile warning when CONFIG_BUG=n, but CONFIG_BUG=n is silly and I never worry about it.
| |