Upon every shm_lock call, we BUG_ON if an error was returned, indicating racing either in idr or in RMID. Move this logic into the locking.
Signed-off-by: Davidlohr Bueso <dbu...@suse.de> --- ipc/shm.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/ipc/shm.c b/ipc/shm.c index 6d76707..3152dea 100644 --- 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 RMID, + * either way, the ID is busted. + */ + BUG_ON(1); return (struct shmid_kernel *)ipcp; + } return container_of(ipcp, struct shmid_kernel, shm_perm); } @@ -191,7 +197,6 @@ static void shm_open(struct vm_area_struct *vma) struct shmid_kernel *shp; shp = shm_lock(sfd->ns, sfd->id); - BUG_ON(IS_ERR(shp)); shp->shm_atim = get_seconds(); shp->shm_lprid = task_tgid_vnr(current); shp->shm_nattch++; @@ -258,7 +263,6 @@ static void shm_close(struct vm_area_struct *vma) down_write(&shm_ids(ns).rwsem); /* remove from the list of attaches of the shm segment */ shp = shm_lock(ns, sfd->id); - BUG_ON(IS_ERR(shp)); shp->shm_lprid = task_tgid_vnr(current); shp->shm_dtim = get_seconds(); shp->shm_nattch--; @@ -1191,7 +1195,6 @@ out_fput: out_nattch: down_write(&shm_ids(ns).rwsem); shp = shm_lock(ns, shmid); - BUG_ON(IS_ERR(shp)); shp->shm_nattch--; if (shm_may_destroy(ns, shp)) shm_destroy(ns, shp); -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/