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eCryptfs: Fix lockdep warning in miscdev operations 

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>
This commit is contained in:
Tyler Hicks 2012-06-11 10:21:34 -07:00
parent 9fe79d7600
commit 60d65f1f07
1 changed files with 13 additions and 12 deletions
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25
fs/ecryptfs/miscdev.c
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@ -191,31 +191,32 @@ int ecryptfs_send_miscdev(char *data, size_t data_size,
struct ecryptfs_msg_ctx *msg_ctx, u8 msg_type, struct ecryptfs_msg_ctx *msg_ctx, u8 msg_type,
u16 msg_flags, struct ecryptfs_daemon *daemon) u16 msg_flags, struct ecryptfs_daemon *daemon)
{ {
int rc = 0; struct ecryptfs_message *msg;
mutex_lock(&msg_ctx->mux); msg = kmalloc((sizeof(*msg) + data_size), GFP_KERNEL);
msg_ctx->msg = kmalloc((sizeof(*msg_ctx->msg) + data_size), if (!msg) {
GFP_KERNEL);
if (!msg_ctx->msg) {
rc = -ENOMEM;
printk(KERN_ERR "%s: Out of memory whilst attempting " printk(KERN_ERR "%s: Out of memory whilst attempting "
"to kmalloc(%zd, GFP_KERNEL)\n", __func__, "to kmalloc(%zd, GFP_KERNEL)\n", __func__,
(sizeof(*msg_ctx->msg) + data_size)); (sizeof(*msg) + data_size));
goto out_unlock; return -ENOMEM;
} }
mutex_lock(&msg_ctx->mux);
msg_ctx->msg = msg;
msg_ctx->msg->index = msg_ctx->index; msg_ctx->msg->index = msg_ctx->index;
msg_ctx->msg->data_len = data_size; msg_ctx->msg->data_len = data_size;
msg_ctx->type = msg_type; msg_ctx->type = msg_type;
memcpy(msg_ctx->msg->data, data, data_size); memcpy(msg_ctx->msg->data, data, data_size);
msg_ctx->msg_size = (sizeof(*msg_ctx->msg) + 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); 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++; daemon->num_queued_msg_ctx++;
wake_up_interruptible(&daemon->wait); wake_up_interruptible(&daemon->wait);
mutex_unlock(&daemon->mux); mutex_unlock(&daemon->mux);
out_unlock:
mutex_unlock(&msg_ctx->mux); return 0;
return rc;
} }
/* /*