diff mbox series

[v2,1/2] Bluetooth: ISO: Fix circular locking dependency warning

Message ID 20240305140939.5090-2-iulia.tanasescu@nxp.com (mailing list archive)
State Superseded
Headers show
Series Bluetooth: ISO: iso_listen_bis fixes | expand

Checks

Context Check Description
tedd_an/pre-ci_am success Success
tedd_an/CheckPatch success CheckPatch PASS
tedd_an/GitLint success Gitlint PASS
tedd_an/SubjectPrefix success Gitlint PASS
tedd_an/BuildKernel success BuildKernel PASS
tedd_an/CheckAllWarning success CheckAllWarning PASS
tedd_an/CheckSparse success CheckSparse PASS
tedd_an/CheckSmatch success CheckSparse PASS
tedd_an/BuildKernel32 success BuildKernel32 PASS
tedd_an/TestRunnerSetup success TestRunnerSetup PASS
tedd_an/TestRunner_l2cap-tester success TestRunner PASS
tedd_an/TestRunner_iso-tester fail TestRunner_iso-tester: Total: 117, Passed: 115 (98.3%), Failed: 2, Not Run: 0
tedd_an/TestRunner_bnep-tester success TestRunner PASS
tedd_an/TestRunner_mgmt-tester fail TestRunner_mgmt-tester: Total: 492, Passed: 489 (99.4%), Failed: 1, Not Run: 2
tedd_an/TestRunner_rfcomm-tester success TestRunner PASS
tedd_an/TestRunner_sco-tester success TestRunner PASS
tedd_an/TestRunner_ioctl-tester success TestRunner PASS
tedd_an/TestRunner_mesh-tester success TestRunner PASS
tedd_an/TestRunner_smp-tester success TestRunner PASS
tedd_an/TestRunner_userchan-tester success TestRunner PASS
tedd_an/IncrementalBuild success Incremental Build PASS

Commit Message

Iulia Tanasescu March 5, 2024, 2:09 p.m. UTC 
This fixes the circular locking dependency warning caused
by iso_listen_bis acquiring the hdev lock while the socket
has been locked in the caller function.

======================================================
WARNING: possible circular locking dependency detected
6.8.0-rc5+ #1 Not tainted
------------------------------------------------------
iso-tester/2950 is trying to acquire lock:
ffff88817a048080 (&hdev->lock){+.+.}-{3:3}, at: iso_sock_listen+0x305/0x8d0

               but task is already holding lock:
ffff888197c39278 (sk_lock-AF_BLUETOOTH-BTPROTO_ISO){+.+.}-{0:0},
               at: iso_sock_listen+0x91/0x8d0

               which lock already depends on the new lock.

               the existing dependency chain (in reverse order) is:

 -> #1 (sk_lock-AF_BLUETOOTH-BTPROTO_ISO){+.+.}-{0:0}:
        lock_sock_nested+0x3b/0xb0
        iso_connect_cis+0x185/0x540
        iso_sock_connect+0x445/0x7e0
        __sys_connect_file+0xd5/0x100
        __sys_connect+0x11e/0x150
        __x64_sys_connect+0x42/0x60
        do_syscall_64+0x8d/0x150
        entry_SYSCALL_64_after_hwframe+0x6e/0x76

-> #0 (&hdev->lock){+.+.}-{3:3}:
        __lock_acquire+0x208f/0x3720
        lock_acquire+0x16d/0x3f0
        __mutex_lock+0x155/0x1310
        mutex_lock_nested+0x1b/0x30
        iso_sock_listen+0x305/0x8d0
        __sys_listen+0x106/0x190
        __x64_sys_listen+0x30/0x40
        do_syscall_64+0x8d/0x150
        entry_SYSCALL_64_after_hwframe+0x6e/0x76

        other info that might help us debug this:

Possible unsafe locking scenario:

        CPU0                    CPU1
        ----                    ----
   lock(sk_lock-AF_BLUETOOTH-BTPROTO_ISO);
                                lock(&hdev->lock);
                                lock(sk_lock-AF_BLUETOOTH-BTPROTO_ISO);
   lock(&hdev->lock);

                *** DEADLOCK ***

1 lock held by iso-tester/2950:
0: ffff888197c39278 (sk_lock-AF_BLUETOOTH-BTPROTO_ISO){+.+.}-{0:0},
                at: iso_sock_listen+0x91/0x8d0

Signed-off-by: Iulia Tanasescu <iulia.tanasescu@nxp.com>
---
 net/bluetooth/iso.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

Comments

bluez.test.bot@gmail.com March 5, 2024, 2:32 p.m. UTC | #1 
This is automated email and please do not reply to this email!

Dear submitter,

Thank you for submitting the patches to the linux bluetooth mailing list.
This is a CI test results with your patch series:
PW Link:https://patchwork.kernel.org/project/bluetooth/list/?series=832552

---Test result---

Test Summary:
CheckPatch                    PASS      1.29 seconds
GitLint                       PASS      0.62 seconds
SubjectPrefix                 PASS      0.24 seconds
BuildKernel                   PASS      28.06 seconds
CheckAllWarning               PASS      30.78 seconds
CheckSparse                   PASS      36.42 seconds
CheckSmatch                   PASS      99.56 seconds
BuildKernel32                 PASS      27.63 seconds
TestRunnerSetup               PASS      504.40 seconds
TestRunner_l2cap-tester       PASS      20.25 seconds
TestRunner_iso-tester         FAIL      37.26 seconds
TestRunner_bnep-tester        PASS      4.87 seconds
TestRunner_mgmt-tester        FAIL      110.92 seconds
TestRunner_rfcomm-tester      PASS      7.43 seconds
TestRunner_sco-tester         PASS      17.06 seconds
TestRunner_ioctl-tester       PASS      7.97 seconds
TestRunner_mesh-tester        PASS      5.97 seconds
TestRunner_smp-tester         PASS      7.04 seconds
TestRunner_userchan-tester    PASS      5.22 seconds
IncrementalBuild              PASS      31.97 seconds

Details
##############################
Test: TestRunner_iso-tester - FAIL
Desc: Run iso-tester with test-runner
Output:
Total: 117, Passed: 115 (98.3%), Failed: 2, Not Run: 0

Failed Test Cases
ISO Connect Suspend - Success                        Failed       4.186 seconds
ISO Connect2 Suspend - Success                       Failed       4.211 seconds
##############################
Test: TestRunner_mgmt-tester - FAIL
Desc: Run mgmt-tester with test-runner
Output:
Total: 492, Passed: 489 (99.4%), Failed: 1, Not Run: 2

Failed Test Cases
LL Privacy - Add Device 7 (AL is full)               Failed       0.198 seconds


---
Regards,
Linux Bluetooth
Pauli Virtanen March 6, 2024, 4:11 p.m. UTC | #2 
Hi,

ti, 2024-03-05 kello 16:09 +0200, Iulia Tanasescu kirjoitti:
> This fixes the circular locking dependency warning caused
> by iso_listen_bis acquiring the hdev lock while the socket
> has been locked in the caller function.

I think the commit message and the comment should explain why there is
no deadlock, and that the lockdep warning is a false positive.

E.g. fuzzer calling connect() and listen() at the same time seems it
would be dangerous here?

> 
> ======================================================
> WARNING: possible circular locking dependency detected
> 6.8.0-rc5+ #1 Not tainted
> ------------------------------------------------------
> iso-tester/2950 is trying to acquire lock:
> ffff88817a048080 (&hdev->lock){+.+.}-{3:3}, at: iso_sock_listen+0x305/0x8d0
> 
>                but task is already holding lock:
> ffff888197c39278 (sk_lock-AF_BLUETOOTH-BTPROTO_ISO){+.+.}-{0:0},
>                at: iso_sock_listen+0x91/0x8d0
> 
>                which lock already depends on the new lock.
> 
>                the existing dependency chain (in reverse order) is:
> 
>  -> #1 (sk_lock-AF_BLUETOOTH-BTPROTO_ISO){+.+.}-{0:0}:
>         lock_sock_nested+0x3b/0xb0
>         iso_connect_cis+0x185/0x540
>         iso_sock_connect+0x445/0x7e0
>         __sys_connect_file+0xd5/0x100
>         __sys_connect+0x11e/0x150
>         __x64_sys_connect+0x42/0x60
>         do_syscall_64+0x8d/0x150
>         entry_SYSCALL_64_after_hwframe+0x6e/0x76
> 
> -> #0 (&hdev->lock){+.+.}-{3:3}:
>         __lock_acquire+0x208f/0x3720
>         lock_acquire+0x16d/0x3f0
>         __mutex_lock+0x155/0x1310
>         mutex_lock_nested+0x1b/0x30
>         iso_sock_listen+0x305/0x8d0
>         __sys_listen+0x106/0x190
>         __x64_sys_listen+0x30/0x40
>         do_syscall_64+0x8d/0x150
>         entry_SYSCALL_64_after_hwframe+0x6e/0x76
> 
>         other info that might help us debug this:
> 
> Possible unsafe locking scenario:
> 
>         CPU0                    CPU1
>         ----                    ----
>    lock(sk_lock-AF_BLUETOOTH-BTPROTO_ISO);
>                                 lock(&hdev->lock);
>                                 lock(sk_lock-AF_BLUETOOTH-BTPROTO_ISO);
>    lock(&hdev->lock);
> 
>                 *** DEADLOCK ***
> 
> 1 lock held by iso-tester/2950:
> 0: ffff888197c39278 (sk_lock-AF_BLUETOOTH-BTPROTO_ISO){+.+.}-{0:0},
>                 at: iso_sock_listen+0x91/0x8d0
> 
> Signed-off-by: Iulia Tanasescu <iulia.tanasescu@nxp.com>
> ---
>  net/bluetooth/iso.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/net/bluetooth/iso.c b/net/bluetooth/iso.c
> index 8af75d37b14c..5ca7bb0806b0 100644
> --- a/net/bluetooth/iso.c
> +++ b/net/bluetooth/iso.c
> @@ -1095,7 +1095,10 @@ static int iso_listen_bis(struct sock *sk)
>  	if (!hdev)
>  		return -EHOSTUNREACH;
>  
> -	hci_dev_lock(hdev);
> +	/* To avoid circular locking dependency warnings,
> +	 * use nested lock for hdev.
> +	 */
> +	mutex_lock_nested(&hdev->lock, SINGLE_DEPTH_NESTING);
>  
>  	/* Fail if user set invalid QoS */
>  	if (iso_pi(sk)->qos_user_set && !check_bcast_qos(&iso_pi(sk)->qos)) {
diff mbox series

Patch

diff --git a/net/bluetooth/iso.c b/net/bluetooth/iso.c
index 8af75d37b14c..5ca7bb0806b0 100644
--- a/net/bluetooth/iso.c
+++ b/net/bluetooth/iso.c
@@ -1095,7 +1095,10 @@  static int iso_listen_bis(struct sock *sk)
 	if (!hdev)
 		return -EHOSTUNREACH;
 
-	hci_dev_lock(hdev);
+	/* To avoid circular locking dependency warnings,
+	 * use nested lock for hdev.
+	 */
+	mutex_lock_nested(&hdev->lock, SINGLE_DEPTH_NESTING);
 
 	/* Fail if user set invalid QoS */
 	if (iso_pi(sk)->qos_user_set && !check_bcast_qos(&iso_pi(sk)->qos)) {