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Jiri Kosina 17486960d7 Bluetooth: avoid deadlock between hci_dev->lock and socket lock 
Commit eab2404ba7 ("Bluetooth: Add BT_PHY socket option") added a
dependency between socket lock and hci_dev->lock that could lead to
deadlock.

It turns out that hci_conn_get_phy() is not in any way relying on hdev
being immutable during the runtime of this function, neither does it even
look at any of the members of hdev, and as such there is no need to hold
that lock.

This fixes the lockdep splat below:

 ======================================================
 WARNING: possible circular locking dependency detected
 5.12.0-rc1-00026-g73d464503354 #10 Not tainted
 ------------------------------------------------------
 bluetoothd/1118 is trying to acquire lock:
 ffff8f078383c078 (&hdev->lock){+.+.}-{3:3}, at: hci_conn_get_phy+0x1c/0x150 [bluetooth]

 but task is already holding lock:
 ffff8f07e831d920 (sk_lock-AF_BLUETOOTH-BTPROTO_L2CAP){+.+.}-{0:0}, at: l2cap_sock_getsockopt+0x8b/0x610

 which lock already depends on the new lock.

 the existing dependency chain (in reverse order) is:

 -> #3 (sk_lock-AF_BLUETOOTH-BTPROTO_L2CAP){+.+.}-{0:0}:
        lock_sock_nested+0x72/0xa0
        l2cap_sock_ready_cb+0x18/0x70 [bluetooth]
        l2cap_config_rsp+0x27a/0x520 [bluetooth]
        l2cap_sig_channel+0x658/0x1330 [bluetooth]
        l2cap_recv_frame+0x1ba/0x310 [bluetooth]
        hci_rx_work+0x1cc/0x640 [bluetooth]
        process_one_work+0x244/0x5f0
        worker_thread+0x3c/0x380
        kthread+0x13e/0x160
        ret_from_fork+0x22/0x30

 -> #2 (&chan->lock#2/1){+.+.}-{3:3}:
        __mutex_lock+0xa3/0xa10
        l2cap_chan_connect+0x33a/0x940 [bluetooth]
        l2cap_sock_connect+0x141/0x2a0 [bluetooth]
        __sys_connect+0x9b/0xc0
        __x64_sys_connect+0x16/0x20
        do_syscall_64+0x33/0x80
        entry_SYSCALL_64_after_hwframe+0x44/0xae

 -> #1 (&conn->chan_lock){+.+.}-{3:3}:
        __mutex_lock+0xa3/0xa10
        l2cap_chan_connect+0x322/0x940 [bluetooth]
        l2cap_sock_connect+0x141/0x2a0 [bluetooth]
        __sys_connect+0x9b/0xc0
        __x64_sys_connect+0x16/0x20
        do_syscall_64+0x33/0x80
        entry_SYSCALL_64_after_hwframe+0x44/0xae

 -> #0 (&hdev->lock){+.+.}-{3:3}:
        __lock_acquire+0x147a/0x1a50
        lock_acquire+0x277/0x3d0
        __mutex_lock+0xa3/0xa10
        hci_conn_get_phy+0x1c/0x150 [bluetooth]
        l2cap_sock_getsockopt+0x5a9/0x610 [bluetooth]
        __sys_getsockopt+0xcc/0x200
        __x64_sys_getsockopt+0x20/0x30
        do_syscall_64+0x33/0x80
        entry_SYSCALL_64_after_hwframe+0x44/0xae

 other info that might help us debug this:

 Chain exists of:
   &hdev->lock --> &chan->lock#2/1 --> sk_lock-AF_BLUETOOTH-BTPROTO_L2CAP

  Possible unsafe locking scenario:

        CPU0                    CPU1
        ----                    ----
   lock(sk_lock-AF_BLUETOOTH-BTPROTO_L2CAP);
                                lock(&chan->lock#2/1);
                                lock(sk_lock-AF_BLUETOOTH-BTPROTO_L2CAP);
   lock(&hdev->lock);

  *** DEADLOCK ***

 1 lock held by bluetoothd/1118:
  #0: ffff8f07e831d920 (sk_lock-AF_BLUETOOTH-BTPROTO_L2CAP){+.+.}-{0:0}, at: l2cap_sock_getsockopt+0x8b/0x610 [bluetooth]

 stack backtrace:
 CPU: 3 PID: 1118 Comm: bluetoothd Not tainted 5.12.0-rc1-00026-g73d464503354 #10
 Hardware name: LENOVO 20K5S22R00/20K5S22R00, BIOS R0IET38W (1.16 ) 05/31/2017
 Call Trace:
  dump_stack+0x7f/0xa1
  check_noncircular+0x105/0x120
  ? __lock_acquire+0x147a/0x1a50
  __lock_acquire+0x147a/0x1a50
  lock_acquire+0x277/0x3d0
  ? hci_conn_get_phy+0x1c/0x150 [bluetooth]
  ? __lock_acquire+0x2e1/0x1a50
  ? lock_is_held_type+0xb4/0x120
  ? hci_conn_get_phy+0x1c/0x150 [bluetooth]
  __mutex_lock+0xa3/0xa10
  ? hci_conn_get_phy+0x1c/0x150 [bluetooth]
  ? lock_acquire+0x277/0x3d0
  ? mark_held_locks+0x49/0x70
  ? mark_held_locks+0x49/0x70
  ? hci_conn_get_phy+0x1c/0x150 [bluetooth]
  hci_conn_get_phy+0x1c/0x150 [bluetooth]
  l2cap_sock_getsockopt+0x5a9/0x610 [bluetooth]
  __sys_getsockopt+0xcc/0x200
  __x64_sys_getsockopt+0x20/0x30
  do_syscall_64+0x33/0x80
  entry_SYSCALL_64_after_hwframe+0x44/0xae
 RIP: 0033:0x7fb73df33eee
 Code: 48 8b 0d 85 0f 0c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 49 89 ca b8 37 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 52 0f 0c 00 f7 d8 64 89 01 48
 RSP: 002b:00007fffcfbbbf08 EFLAGS: 00000203 ORIG_RAX: 0000000000000037
 RAX: ffffffffffffffda RBX: 0000000000000019 RCX: 00007fb73df33eee
 RDX: 000000000000000e RSI: 0000000000000112 RDI: 0000000000000018
 RBP: 0000000000000000 R08: 00007fffcfbbbf44 R09: 0000000000000000
 R10: 00007fffcfbbbf3c R11: 0000000000000203 R12: 0000000000000000
 R13: 0000000000000018 R14: 0000000000000000 R15: 0000556fcefc70d0

Fixes: eab2404ba7 ("Bluetooth: Add BT_PHY socket option")
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
 		2021-03-16 15:29:25 +01:00
Documentation Bluetooth: btbcm: Rewrite bindings in YAML and add reset 2021-03-08 10:25:49 +01:00
LICENSES LICENSES: Add the CC-BY-4.0 license 2020-12-08 10:33:27 -07:00
arch The performance event updates for v5.12 are: 2021-02-21 12:49:32 -08:00
block for-5.12/block-2021-02-17 2021-02-21 11:02:48 -08:00
certs .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
crypto X.509: Fix crash caused by NULL pointer 2021-01-20 11:33:51 -08:00
drivers Bluetooth: hci_qca: Add device_may_wakeup support 2021-03-11 11:48:49 +01:00
fs These changes fix MM (soft-)dirty bit management in the procfs code & clean up the API. 2021-02-21 12:19:56 -08:00
include Bluetooth: L2CAP: Fix not checking for maximum number of DCID 2021-03-15 21:08:33 +01:00
init Scheduler updates for v5.12: 2021-02-21 12:35:04 -08:00
ipc Merge branch 'akpm' (patches from Andrew) 2020-12-15 12:53:37 -08:00
kernel The performance event updates for v5.12 are: 2021-02-21 12:49:32 -08:00
lib Scheduler updates for v5.12: 2021-02-21 12:35:04 -08:00
mm These changes fix MM (soft-)dirty bit management in the procfs code & clean up the API. 2021-02-21 12:19:56 -08:00
net Bluetooth: avoid deadlock between hci_dev->lock and socket lock 2021-03-16 15:29:25 +01:00
samples samples: bpf: Remove unneeded semicolon 2021-02-02 21:37:59 -08:00
scripts These are the v5.12 updates for the locking subsystem: 2021-02-21 12:12:01 -08:00
security cap: fix conversions on getxattr 2021-01-28 10:22:48 +01:00
sound Merge branches 'acpi-misc', 'acpi-cppc', 'acpi-docs', 'acpi-config' and 'acpi-apei' 2021-02-15 17:04:40 +01:00
tools Scheduler updates for v5.12: 2021-02-21 12:35:04 -08:00
usr arch: ia64: Remove rest of perfmon support 2021-01-22 12:12:20 +05:30
virt KVM/arm64 fixes for 5.11, take #2 2021-01-25 18:52:01 -05:00
.clang-format clang-format: Update with the latest for_each macro list 2021-01-29 15:00:23 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: docs: ignore sphinx_*/ directories 2020-09-10 10:44:31 -06:00
.mailmap MAINTAINERS: update Andrey Ryabinin's email address 2021-02-09 17:26:44 -08:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: dccp: move Gerrit Renker to CREDITS 2021-01-14 10:53:49 -08:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS These are the v5.12 updates for the locking subsystem: 2021-02-21 12:12:01 -08:00
Makefile Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next 2021-02-20 17:45:32 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.