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SubjectRe: [v2.6.26-rc1] possible circular locking in ecryptfs
[Ingo Molnar - Sun, May 18, 2008 at 01:40:20PM +0200]
|
| * Cyrill Gorcunov <gorcunov@gmail.com> wrote:
|
| > [Ingo Molnar - Fri, May 09, 2008 at 11:44:23AM +0200]
| > |
| > | * Ingo Molnar <mingo@elte.hu> wrote:
| > |
| > | > x86.git testing found the following "possible circular locking"
| > | > lockdep warning, generated by the ecryptfs code:
| > |
| > | the correct URL for the config is:
| > |
| > | http://redhat.com/~mingo/misc/config-Wed_May__7_16_17_31_CEST_2008.bad
| > |
| > | this is reproducible, it happened a second time since i originally
| > | reported it.
| > |
| > | Ingo
| >
| > Hi Ingo, I've just sent patch, could you test it, please?
| >
| > http://lkml.org/lkml/2008/5/10/20
|
| that patch is now upstream - but see below there's still a circular
| dependency.
|
| Ingo
|
|

Ingo, could you test this patch please? If it help I will send
it in normal way.

- Cyrill -
---
Index: linux-2.6.git/fs/ecryptfs/miscdev.c
===================================================================
--- linux-2.6.git.orig/fs/ecryptfs/miscdev.c 2008-05-18 18:53:56.000000000 +0400
+++ linux-2.6.git/fs/ecryptfs/miscdev.c 2008-05-18 19:08:25.000000000 +0400
@@ -50,7 +50,6 @@ ecryptfs_miscdev_poll(struct file *file,
current->nsproxy->user_ns);
BUG_ON(rc || !daemon);
mutex_lock(&daemon->mux);
- mutex_unlock(&ecryptfs_daemon_hash_mux);
if (daemon->flags & ECRYPTFS_DAEMON_ZOMBIE) {
printk(KERN_WARNING "%s: Attempt to poll on zombified "
"daemon\n", __func__);
@@ -62,6 +61,7 @@ ecryptfs_miscdev_poll(struct file *file,
goto out_unlock_daemon;
daemon->flags |= ECRYPTFS_DAEMON_IN_POLL;
mutex_unlock(&daemon->mux);
+ mutex_unlock(&ecryptfs_daemon_hash_mux);
poll_wait(file, &daemon->wait, pt);
mutex_lock(&daemon->mux);
if (!list_empty(&daemon->msg_ctx_out_queue))
@@ -69,6 +69,8 @@ ecryptfs_miscdev_poll(struct file *file,
out_unlock_daemon:
daemon->flags &= ~ECRYPTFS_DAEMON_IN_POLL;
mutex_unlock(&daemon->mux);
+ if (mutex_is_locked(&ecryptfs_daemon_hash_mux))
+ mutex_unlock(&ecryptfs_daemon_hash_mux);
return mask;
}

@@ -257,14 +259,12 @@ ecryptfs_miscdev_read(struct file *file,
mutex_lock(&daemon->mux);
if (daemon->flags & ECRYPTFS_DAEMON_ZOMBIE) {
rc = 0;
- mutex_unlock(&ecryptfs_daemon_hash_mux);
printk(KERN_WARNING "%s: Attempt to read from zombified "
"daemon\n", __func__);
goto out_unlock_daemon;
}
if (daemon->flags & ECRYPTFS_DAEMON_IN_READ) {
rc = 0;
- mutex_unlock(&ecryptfs_daemon_hash_mux);
goto out_unlock_daemon;
}
/* This daemon will not go away so long as this flag is set */
@@ -357,6 +357,8 @@ out_unlock_msg_ctx:
out_unlock_daemon:
daemon->flags &= ~ECRYPTFS_DAEMON_IN_READ;
mutex_unlock(&daemon->mux);
+ if (mutex_is_locked(&ecryptfs_daemon_hash_mux))
+ mutex_unlock(&ecryptfs_daemon_hash_mux);
return rc;
}


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