This is a note to let you know that I've just added the patch titled
ipc,shm: make shmctl_nolock lockless
to the 3.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ipc-shm-make-shmctl_nolock-lockless.patch
and it can be found in the queue-3.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From c97cb9ccab8c85428ec21eff690642ad2ce1fa8a Mon Sep 17 00:00:00 2001
From: Davidlohr Bueso <[email protected]>
Date: Wed, 11 Sep 2013 14:26:20 -0700
Subject: ipc,shm: make shmctl_nolock lockless
From: Davidlohr Bueso <[email protected]>
commit c97cb9ccab8c85428ec21eff690642ad2ce1fa8a upstream.
While the INFO cmd doesn't take the ipc lock, the STAT commands do acquire
it unnecessarily. We can do the permissions and security checks only
holding the rcu lock.
[[email protected]: coding-style fixes]
Signed-off-by: Davidlohr Bueso <[email protected]>
Tested-by: Sedat Dilek <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Manfred Spraul <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Cc: Mike Galbraith <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
ipc/shm.c | 19 ++++++++++++-------
1 file changed, 12 insertions(+), 7 deletions(-)
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -882,27 +882,31 @@ static int shmctl_nolock(struct ipc_name
struct shmid64_ds tbuf;
int result;
+ rcu_read_lock();
if (cmd == SHM_STAT) {
- shp = shm_lock(ns, shmid);
+ shp = shm_obtain_object(ns, shmid);
if (IS_ERR(shp)) {
err = PTR_ERR(shp);
- goto out;
+ goto out_unlock;
}
result = shp->shm_perm.id;
} else {
- shp = shm_lock_check(ns, shmid);
+ shp = shm_obtain_object_check(ns, shmid);
if (IS_ERR(shp)) {
err = PTR_ERR(shp);
- goto out;
+ goto out_unlock;
}
result = 0;
}
+
err = -EACCES;
if (ipcperms(ns, &shp->shm_perm, S_IRUGO))
goto out_unlock;
+
err = security_shm_shmctl(shp, cmd);
if (err)
goto out_unlock;
+
memset(&tbuf, 0, sizeof(tbuf));
kernel_to_ipc64_perm(&shp->shm_perm, &tbuf.shm_perm);
tbuf.shm_segsz = shp->shm_segsz;
@@ -912,8 +916,9 @@ static int shmctl_nolock(struct ipc_name
tbuf.shm_cpid = shp->shm_cprid;
tbuf.shm_lpid = shp->shm_lprid;
tbuf.shm_nattch = shp->shm_nattch;
- shm_unlock(shp);
- if(copy_shmid_to_user (buf, &tbuf, version))
+ rcu_read_unlock();
+
+ if (copy_shmid_to_user(buf, &tbuf, version))
err = -EFAULT;
else
err = result;
@@ -924,7 +929,7 @@ static int shmctl_nolock(struct ipc_name
}
out_unlock:
- shm_unlock(shp);
+ rcu_read_unlock();
out:
return err;
}
Patches currently in stable-queue which might be from [email protected] are
queue-3.10/ipc-shm-shorten-critical-region-in-shmctl_down.patch
queue-3.10/ipc-msg-introduce-lockless-functions-to-obtain-the-ipc-object.patch
queue-3.10/ipc-msg-shorten-critical-region-in-msgctl_down.patch
queue-3.10/ipc-shm-introduce-lockless-functions-to-obtain-the-ipc-object.patch
queue-3.10/ipc-remove-unused-functions.patch
queue-3.10/ipc-shm-shorten-critical-region-for-shmat.patch
queue-3.10/ipc-msg-introduce-msgctl_nolock.patch
queue-3.10/ipc-move-rcu-lock-out-of-ipc_addid.patch
queue-3.10/ipc-sem-separate-wait-for-zero-and-alter-tasks-into-seperate-queues.patch
queue-3.10/ipc-shm-shorten-critical-region-for-shmctl.patch
queue-3.10/ipc-msg-shorten-critical-region-in-msgsnd.patch
queue-3.10/ipc-shm-introduce-shmctl_nolock.patch
queue-3.10/ipc-drop-ipcctl_pre_down.patch
queue-3.10/ipc-util.c-ipc_rcu_alloc-cacheline-align-allocation.patch
queue-3.10/ipc-introduce-ipc-object-locking-helpers.patch
queue-3.10/ipc-sem.c-cacheline-align-the-semaphore-structures.patch
queue-3.10/ipc-msg-shorten-critical-region-in-msgrcv.patch
queue-3.10/ipc-msg-make-msgctl_nolock-lockless.patch
queue-3.10/ipc-sem.c-always-use-only-one-queue-for-alter-operations.patch
queue-3.10/ipc-shm-cleanup-do_shmat-pasta.patch
queue-3.10/ipc-move-locking-out-of-ipcctl_pre_down_nolock.patch
queue-3.10/ipc-close-open-coded-spin-lock-calls.patch
queue-3.10/ipc-sem.c-rename-try_atomic_semop-to-perform_atomic_semop-docu-update.patch
queue-3.10/ipc-shm-make-shmctl_nolock-lockless.patch
queue-3.10/ipc-sem.c-replace-shared-sem_otime-with-per-semaphore-value.patch
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