3.16.60-rc1 review patch. If anyone has any objections, please let me know.
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From: Davidlohr Bueso dave@stgolabs.net
commit c5c8975b2eb4eb7604e8ce4f762987f56d2a96a2 upstream.
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.
[akpm@linux-foundation.org: simplify code] Signed-off-by: Davidlohr Bueso dbueso@suse.de Cc: Manfred Spraul manfred@colorfullife.com Cc: Davidlohr Bueso dave@stgolabs.net Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Ben Hutchings ben@decadent.org.uk --- ipc/shm.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-)
--- a/ipc/shm.c +++ b/ipc/shm.c @@ -155,8 +155,11 @@ static inline struct shmid_kernel *shm_l { struct kern_ipc_perm *ipcp = ipc_lock(&shm_ids(ns), id);
- if (IS_ERR(ipcp)) - 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); } @@ -190,7 +193,6 @@ static void shm_open(struct vm_area_stru 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++; @@ -256,7 +258,6 @@ static void shm_close(struct vm_area_str 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--; @@ -1199,7 +1200,6 @@ 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);