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Subject[PATCH] eCryptfs: Remove useless lock
On Wed, May 21, 2008 at 10:14:30AM -0500, Michael Halcrow wrote:
> On Wed, May 21, 2008 at 01:16:15AM +0200, Andrea Righi wrote:
> > Michael Halcrow wrote:
> >> + req = kmem_cache_alloc(ecryptfs_open_req_cache, GFP_KERNEL);
> >> + if (!req) {
> >> + rc = -ENOMEM;
> >> + goto out;
> >> + }
> >> + mutex_init(&req->mux);
> >> + req->lower_file = lower_file;
> >> + req->lower_dentry = lower_dentry;
> >> + req->lower_mnt = lower_mnt;
> >> + req->requesting_task = current;
> >> + req->flags = 0;
> >> + mutex_lock(&ecryptfs_kthread_ctl.mux);
> >> + mutex_lock(&req->mux);
> >> + if (ecryptfs_kthread_ctl.flags & ECRYPTFS_KTHREAD_ZOMBIE) {
> >> + rc = -EIO;
> >
> > Isn't a mutex_unlock(&req->mux) missing here?
>
> Nobody else actually has a reference to req at this point, so the
> unlock is not really necessary. It might not be a bad idea to jump to
> out_unlock anyway just to avoid future bugs.
>
> >> + mutex_unlock(&ecryptfs_kthread_ctl.mux);
> >> + printk(KERN_ERR "%s: We are in the middle of shutting down; "
> >> + "aborting privileged request to open lower file\n",
> >> + __func__);
> >> + goto out_free;
> >> + }
> >> + list_add_tail(&req->kthread_ctl_list, &ecryptfs_kthread_ctl.req_list);
> >> + mutex_unlock(&req->mux);
> >> + mutex_unlock(&ecryptfs_kthread_ctl.mux);

Nobody can get a reference to req so long as &ecryptfs_kthread_ctl.mux
is held. Remove lock of req->mux for newly created req.

Signed-off-by: Michael Halcrow <mhalcrow@us.ibm.com>
---
fs/ecryptfs/kthread.c | 2 --
1 files changed, 0 insertions(+), 2 deletions(-)

diff --git a/fs/ecryptfs/kthread.c b/fs/ecryptfs/kthread.c
index dba7c67..3d34327 100644
--- a/fs/ecryptfs/kthread.c
+++ b/fs/ecryptfs/kthread.c
@@ -158,7 +158,6 @@ int ecryptfs_privileged_open(struct file **lower_file,
req->requesting_task = current;
req->flags = 0;
mutex_lock(&ecryptfs_kthread_ctl.mux);
- mutex_lock(&req->mux);
if (ecryptfs_kthread_ctl.flags & ECRYPTFS_KTHREAD_ZOMBIE) {
rc = -EIO;
mutex_unlock(&ecryptfs_kthread_ctl.mux);
@@ -168,7 +167,6 @@ int ecryptfs_privileged_open(struct file **lower_file,
goto out_free;
}
list_add_tail(&req->kthread_ctl_list, &ecryptfs_kthread_ctl.req_list);
- mutex_unlock(&req->mux);
mutex_unlock(&ecryptfs_kthread_ctl.mux);
wake_up(&ecryptfs_kthread_ctl.wait);
schedule:
--
1.5.3.6


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