| From: Tyler Hicks <tyhicks@canonical.com> |
| Date: Mon, 11 Jun 2012 10:21:34 -0700 |
| Subject: eCryptfs: Fix lockdep warning in miscdev operations |
| |
| commit 60d65f1f07a7d81d3eb3b91fc13fca80f2fdbb12 upstream. |
| |
| Don't grab the daemon mutex while holding the message context mutex. |
| Addresses this lockdep warning: |
| |
| ecryptfsd/2141 is trying to acquire lock: |
| (&ecryptfs_msg_ctx_arr[i].mux){+.+.+.}, at: [<ffffffffa029c213>] ecryptfs_miscdev_read+0x143/0x470 [ecryptfs] |
| |
| but task is already holding lock: |
| (&(*daemon)->mux){+.+...}, at: [<ffffffffa029c2ec>] ecryptfs_miscdev_read+0x21c/0x470 [ecryptfs] |
| |
| which lock already depends on the new lock. |
| |
| the existing dependency chain (in reverse order) is: |
| |
| -> #1 (&(*daemon)->mux){+.+...}: |
| [<ffffffff810a3b8d>] lock_acquire+0x9d/0x220 |
| [<ffffffff8151c6da>] __mutex_lock_common+0x5a/0x4b0 |
| [<ffffffff8151cc64>] mutex_lock_nested+0x44/0x50 |
| [<ffffffffa029c5d7>] ecryptfs_send_miscdev+0x97/0x120 [ecryptfs] |
| [<ffffffffa029b744>] ecryptfs_send_message+0x134/0x1e0 [ecryptfs] |
| [<ffffffffa029a24e>] ecryptfs_generate_key_packet_set+0x2fe/0xa80 [ecryptfs] |
| [<ffffffffa02960f8>] ecryptfs_write_metadata+0x108/0x250 [ecryptfs] |
| [<ffffffffa0290f80>] ecryptfs_create+0x130/0x250 [ecryptfs] |
| [<ffffffff811963a4>] vfs_create+0xb4/0x120 |
| [<ffffffff81197865>] do_last+0x8c5/0xa10 |
| [<ffffffff811998f9>] path_openat+0xd9/0x460 |
| [<ffffffff81199da2>] do_filp_open+0x42/0xa0 |
| [<ffffffff81187998>] do_sys_open+0xf8/0x1d0 |
| [<ffffffff81187a91>] sys_open+0x21/0x30 |
| [<ffffffff81527d69>] system_call_fastpath+0x16/0x1b |
| |
| -> #0 (&ecryptfs_msg_ctx_arr[i].mux){+.+.+.}: |
| [<ffffffff810a3418>] __lock_acquire+0x1bf8/0x1c50 |
| [<ffffffff810a3b8d>] lock_acquire+0x9d/0x220 |
| [<ffffffff8151c6da>] __mutex_lock_common+0x5a/0x4b0 |
| [<ffffffff8151cc64>] mutex_lock_nested+0x44/0x50 |
| [<ffffffffa029c213>] ecryptfs_miscdev_read+0x143/0x470 [ecryptfs] |
| [<ffffffff811887d3>] vfs_read+0xb3/0x180 |
| [<ffffffff811888ed>] sys_read+0x4d/0x90 |
| [<ffffffff81527d69>] system_call_fastpath+0x16/0x1b |
| |
| Signed-off-by: Tyler Hicks <tyhicks@canonical.com> |
| Signed-off-by: Ben Hutchings <ben@decadent.org.uk> |
| --- |
| fs/ecryptfs/miscdev.c | 25 +++++++++++++------------ |
| 1 file changed, 13 insertions(+), 12 deletions(-) |
| |
| --- a/fs/ecryptfs/miscdev.c |
| +++ b/fs/ecryptfs/miscdev.c |
| @@ -195,31 +195,32 @@ int ecryptfs_send_miscdev(char *data, si |
| struct ecryptfs_msg_ctx *msg_ctx, u8 msg_type, |
| u16 msg_flags, struct ecryptfs_daemon *daemon) |
| { |
| - int rc = 0; |
| + struct ecryptfs_message *msg; |
| |
| - mutex_lock(&msg_ctx->mux); |
| - msg_ctx->msg = kmalloc((sizeof(*msg_ctx->msg) + data_size), |
| - GFP_KERNEL); |
| - if (!msg_ctx->msg) { |
| - rc = -ENOMEM; |
| + msg = kmalloc((sizeof(*msg) + data_size), GFP_KERNEL); |
| + if (!msg) { |
| printk(KERN_ERR "%s: Out of memory whilst attempting " |
| "to kmalloc(%zd, GFP_KERNEL)\n", __func__, |
| - (sizeof(*msg_ctx->msg) + data_size)); |
| - goto out_unlock; |
| + (sizeof(*msg) + data_size)); |
| + return -ENOMEM; |
| } |
| + |
| + mutex_lock(&msg_ctx->mux); |
| + msg_ctx->msg = msg; |
| msg_ctx->msg->index = msg_ctx->index; |
| msg_ctx->msg->data_len = data_size; |
| msg_ctx->type = msg_type; |
| memcpy(msg_ctx->msg->data, data, data_size); |
| msg_ctx->msg_size = (sizeof(*msg_ctx->msg) + data_size); |
| - mutex_lock(&daemon->mux); |
| list_add_tail(&msg_ctx->daemon_out_list, &daemon->msg_ctx_out_queue); |
| + mutex_unlock(&msg_ctx->mux); |
| + |
| + mutex_lock(&daemon->mux); |
| daemon->num_queued_msg_ctx++; |
| wake_up_interruptible(&daemon->wait); |
| mutex_unlock(&daemon->mux); |
| -out_unlock: |
| - mutex_unlock(&msg_ctx->mux); |
| - return rc; |
| + |
| + return 0; |
| } |
| |
| /** |