[PATCH v3 23/27] misc: use helpers for rlimits

[PATCH v3 23/27] misc: use helpers for rlimits

[Jiri Slaby]

Make sure compiler won't do weird things with limits. E.g. fetching
them twice may return 2 different values after writable limits are
implemented.

I.e. either use newly added rlimit helpers or ACCESS_ONCE if not
applicable.

Signed-off-by: Jiri Slaby <jslaby-AlSwsSmVLrQ@public.gmane.org>
Cc: James Morris <jmorris-gx6/JNMH7DfYtjvyW6yDsg@public.gmane.org>
Cc: Heiko Carstens <heiko.carstens-tA70FqPdS9bQT0dZR+AlfA@public.gmane.org>
Cc: Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>
Cc: Ingo Molnar <mingo-X9Un+BFzKDI@public.gmane.org>
Cc: Roland Dreier <rolandd-FYB4Gu1CFyUAvxtiuMwx3w@public.gmane.org>
Cc: Sean Hefty <sean.hefty-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
Cc: Hal Rosenstock <hal.rosenstock-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
---
 drivers/infiniband/core/umem.c                 |    2 +-
 drivers/infiniband/hw/ipath/ipath_user_pages.c |    3 +--
 ipc/mqueue.c                                   |    2 +-
 ipc/shm.c                                      |    3 +--
 4 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c
index 6f7c096..2a8338a 100644
--- a/drivers/infiniband/core/umem.c
+++ b/drivers/infiniband/core/umem.c
@@ -136,7 +136,7 @@ struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr,
 	down_write(&current->mm->mmap_sem);
 
 	locked     = npages + current->mm->locked_vm;
-	lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur >> PAGE_SHIFT;
+	lock_limit = rlim_get_cur(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
 
 	if ((locked > lock_limit) && !capable(CAP_IPC_LOCK)) {
 		ret = -ENOMEM;
diff --git a/drivers/infiniband/hw/ipath/ipath_user_pages.c b/drivers/infiniband/hw/ipath/ipath_user_pages.c
index 82878e3..431ec61 100644
--- a/drivers/infiniband/hw/ipath/ipath_user_pages.c
+++ b/drivers/infiniband/hw/ipath/ipath_user_pages.c
@@ -59,8 +59,7 @@ static int __get_user_pages(unsigned long start_page, size_t num_pages,
 	size_t got;
 	int ret;
 
-	lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur >>
-		PAGE_SHIFT;
+	lock_limit = rlim_get_cur(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
 
 	if (num_pages > lock_limit) {
 		ret = -ENOMEM;
diff --git a/ipc/mqueue.c b/ipc/mqueue.c
index ee9d697..0e18cde 100644
--- a/ipc/mqueue.c
+++ b/ipc/mqueue.c
@@ -153,7 +153,7 @@ static struct inode *mqueue_get_inode(struct super_block *sb,
 			spin_lock(&mq_lock);
 			if (u->mq_bytes + mq_bytes < u->mq_bytes ||
 		 	    u->mq_bytes + mq_bytes >
-			    p->signal->rlim[RLIMIT_MSGQUEUE].rlim_cur) {
+			    task_rlim_get_cur(p, RLIMIT_MSGQUEUE)) {
 				spin_unlock(&mq_lock);
 				goto out_inode;
 			}
diff --git a/ipc/shm.c b/ipc/shm.c
index 464694e..abd1ebd 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -761,8 +761,7 @@ SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf)
 			if (euid != shp->shm_perm.uid &&
 			    euid != shp->shm_perm.cuid)
 				goto out_unlock;
-			if (cmd == SHM_LOCK &&
-			    !current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur)
+			if (cmd == SHM_LOCK && !rlim_get_cur(RLIMIT_MEMLOCK))
 				goto out_unlock;
 		}
 
-- 
1.6.5.3

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Re: [PATCH v3 23/27] misc: use helpers for rlimits

[Roland Dreier]

Not sure it matters at this part, but for the drivers/infiniband part,
you can add:

Acked-by: Roland Dreier <rolandd-FYB4Gu1CFyUAvxtiuMwx3w@public.gmane.org>

wrapping all the current->signal->rlim[] stuff in a helper function
looks like a nice cleanup independent of the writable limit stuff.

 - R.
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