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Commit c5c8975b authored by Davidlohr Bueso's avatar Davidlohr Bueso Committed by Linus Torvalds
Browse files

ipc,shm: move BUG_ON check into shm_lock 



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: default avatarDavidlohr Bueso <dbueso@suse.de>
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent c859aa83

ipc/shm.c

+5 −5
Original line number Diff line number Diff line
@@ -155,8 +155,11 @@ 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))

		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);

}
@@ -191,7 +194,6 @@ 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 +260,6 @@ 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 +1192,6 @@ long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr, 
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);