[PATCH v2 0/2] Bluetooth: iso: Fix circular lock warnings

[PATCH v2 0/2] Bluetooth: iso: Fix circular lock warnings

[Iulia Tanasescu]

This patch fixes the circular locking dependency warnings in iso.c,
caused by A->B/B->A type lock ordering with sk and hdev.

The first commit fixes the warning caused by iso_listen_bis, by
releasing sk lock before entering the function and acquiring hdev
lock.

The second commit fixes the warning caused by iso_conn_big_sync.
This reworks iso_sock_recvmsg, since it contains multiple function
calls that need sk lock to be released: The socket needs to be kept
alive with sock_hold before being released. To avoid multiple
hold/release/lock/put calls, the socket is grabbed and locked at the
beginning of the switch, and it is released and ungrabbed at the end,
with release/lock calls when necessary in the switch.

Iulia Tanasescu (2):
  Bluetooth: iso: Fix circular lock in iso_listen_bis
  Bluetooth: iso: Fix circular lock in iso_conn_big_sync

 net/bluetooth/iso.c | 48 ++++++++++++++++++++++++++++++++++++---------
 1 file changed, 39 insertions(+), 9 deletions(-)


base-commit: 269f7b219173ffbb01121243c55cef8a5503593b
-- 
2.43.0

[PATCH v2 1/2] Bluetooth: iso: Fix circular lock in iso_listen_bis

[Iulia Tanasescu]

This fixes the circular locking dependency warning below, by
releasing the socket lock before enterning iso_listen_bis, to
avoid any potential deadlock with hdev lock.

[   75.307983] ======================================================
[   75.307984] WARNING: possible circular locking dependency detected
[   75.307985] 6.12.0-rc6+ #22 Not tainted
[   75.307987] ------------------------------------------------------
[   75.307987] kworker/u81:2/2623 is trying to acquire lock:
[   75.307988] ffff8fde1769da58 (sk_lock-AF_BLUETOOTH-BTPROTO_ISO)
               at: iso_connect_cfm+0x253/0x840 [bluetooth]
[   75.308021]
               but task is already holding lock:
[   75.308022] ffff8fdd61a10078 (&hdev->lock)
               at: hci_le_per_adv_report_evt+0x47/0x2f0 [bluetooth]
[   75.308053]
               which lock already depends on the new lock.

[   75.308054]
               the existing dependency chain (in reverse order) is:
[   75.308055]
               -> #1 (&hdev->lock){+.+.}-{3:3}:
[   75.308057]        __mutex_lock+0xad/0xc50
[   75.308061]        mutex_lock_nested+0x1b/0x30
[   75.308063]        iso_sock_listen+0x143/0x5c0 [bluetooth]
[   75.308085]        __sys_listen_socket+0x49/0x60
[   75.308088]        __x64_sys_listen+0x4c/0x90
[   75.308090]        x64_sys_call+0x2517/0x25f0
[   75.308092]        do_syscall_64+0x87/0x150
[   75.308095]        entry_SYSCALL_64_after_hwframe+0x76/0x7e
[   75.308098]
               -> #0 (sk_lock-AF_BLUETOOTH-BTPROTO_ISO){+.+.}-{0:0}:
[   75.308100]        __lock_acquire+0x155e/0x25f0
[   75.308103]        lock_acquire+0xc9/0x300
[   75.308105]        lock_sock_nested+0x32/0x90
[   75.308107]        iso_connect_cfm+0x253/0x840 [bluetooth]
[   75.308128]        hci_connect_cfm+0x6c/0x190 [bluetooth]
[   75.308155]        hci_le_per_adv_report_evt+0x27b/0x2f0 [bluetooth]
[   75.308180]        hci_le_meta_evt+0xe7/0x200 [bluetooth]
[   75.308206]        hci_event_packet+0x21f/0x5c0 [bluetooth]
[   75.308230]        hci_rx_work+0x3ae/0xb10 [bluetooth]
[   75.308254]        process_one_work+0x212/0x740
[   75.308256]        worker_thread+0x1bd/0x3a0
[   75.308258]        kthread+0xe4/0x120
[   75.308259]        ret_from_fork+0x44/0x70
[   75.308261]        ret_from_fork_asm+0x1a/0x30
[   75.308263]
               other info that might help us debug this:

[   75.308264]  Possible unsafe locking scenario:

[   75.308264]        CPU0                CPU1
[   75.308265]        ----                ----
[   75.308265]   lock(&hdev->lock);
[   75.308267]                            lock(sk_lock-
                                                AF_BLUETOOTH-BTPROTO_ISO);
[   75.308268]                            lock(&hdev->lock);
[   75.308269]   lock(sk_lock-AF_BLUETOOTH-BTPROTO_ISO);
[   75.308270]
                *** DEADLOCK ***

[   75.308271] 4 locks held by kworker/u81:2/2623:
[   75.308272]  #0: ffff8fdd66e52148 ((wq_completion)hci0#2){+.+.}-{0:0},
                at: process_one_work+0x443/0x740
[   75.308276]  #1: ffffafb488b7fe48 ((work_completion)(&hdev->rx_work)),
                at: process_one_work+0x1ce/0x740
[   75.308280]  #2: ffff8fdd61a10078 (&hdev->lock){+.+.}-{3:3}
                at: hci_le_per_adv_report_evt+0x47/0x2f0 [bluetooth]
[   75.308304]  #3: ffffffffb6ba4900 (rcu_read_lock){....}-{1:2},
                at: hci_connect_cfm+0x29/0x190 [bluetooth]

Fixes: 02171da6e86a ("Bluetooth: ISO: Add hcon for listening bis sk")
Signed-off-by: Iulia Tanasescu <iulia.tanasescu@nxp.com>
---
 net/bluetooth/iso.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/net/bluetooth/iso.c b/net/bluetooth/iso.c
index 5ca381a3b04b..ed559c82d353 100644
--- a/net/bluetooth/iso.c
+++ b/net/bluetooth/iso.c
@@ -1129,6 +1129,7 @@ static int iso_listen_bis(struct sock *sk)
 		return -EHOSTUNREACH;
 
 	hci_dev_lock(hdev);
+	lock_sock(sk);
 
 	/* Fail if user set invalid QoS */
 	if (iso_pi(sk)->qos_user_set && !check_bcast_qos(&iso_pi(sk)->qos)) {
@@ -1159,6 +1160,7 @@ static int iso_listen_bis(struct sock *sk)
 	}
 
 unlock:
+	release_sock(sk);
 	hci_dev_unlock(hdev);
 	hci_dev_put(hdev);
 	return err;
@@ -1187,6 +1189,7 @@ static int iso_sock_listen(struct socket *sock, int backlog)
 
 	BT_DBG("sk %p backlog %d", sk, backlog);
 
+	sock_hold(sk);
 	lock_sock(sk);
 
 	if (sk->sk_state != BT_BOUND) {
@@ -1199,10 +1202,16 @@ static int iso_sock_listen(struct socket *sock, int backlog)
 		goto done;
 	}
 
-	if (!bacmp(&iso_pi(sk)->dst, BDADDR_ANY))
+	if (!bacmp(&iso_pi(sk)->dst, BDADDR_ANY)) {
 		err = iso_listen_cis(sk);
-	else
+	} else {
+		/* Drop sock lock to avoid potential
+		 * deadlock with the hdev lock.
+		 */
+		release_sock(sk);
 		err = iso_listen_bis(sk);
+		lock_sock(sk);
+	}
 
 	if (err)
 		goto done;
@@ -1214,6 +1223,7 @@ static int iso_sock_listen(struct socket *sock, int backlog)
 
 done:
 	release_sock(sk);
+	sock_put(sk);
 	return err;
 }
 
-- 
2.43.0

[PATCH v2 2/2] Bluetooth: iso: Fix circular lock in iso_conn_big_sync

[Iulia Tanasescu]

This fixes the circular locking dependency warning below, by reworking
iso_sock_recvmsg, to ensure that the socket lock is always released
before calling a function that locks hdev.

[  561.670344] ======================================================
[  561.670346] WARNING: possible circular locking dependency detected
[  561.670349] 6.12.0-rc6+ #26 Not tainted
[  561.670351] ------------------------------------------------------
[  561.670353] iso-tester/3289 is trying to acquire lock:
[  561.670355] ffff88811f600078 (&hdev->lock){+.+.}-{3:3},
               at: iso_conn_big_sync+0x73/0x260 [bluetooth]
[  561.670405]
               but task is already holding lock:
[  561.670407] ffff88815af58258 (sk_lock-AF_BLUETOOTH){+.+.}-{0:0},
               at: iso_sock_recvmsg+0xbf/0x500 [bluetooth]
[  561.670450]
               which lock already depends on the new lock.

[  561.670452]
               the existing dependency chain (in reverse order) is:
[  561.670453]
               -> #2 (sk_lock-AF_BLUETOOTH){+.+.}-{0:0}:
[  561.670458]        lock_acquire+0x7c/0xc0
[  561.670463]        lock_sock_nested+0x3b/0xf0
[  561.670467]        bt_accept_dequeue+0x1a5/0x4d0 [bluetooth]
[  561.670510]        iso_sock_accept+0x271/0x830 [bluetooth]
[  561.670547]        do_accept+0x3dd/0x610
[  561.670550]        __sys_accept4+0xd8/0x170
[  561.670553]        __x64_sys_accept+0x74/0xc0
[  561.670556]        x64_sys_call+0x17d6/0x25f0
[  561.670559]        do_syscall_64+0x87/0x150
[  561.670563]        entry_SYSCALL_64_after_hwframe+0x76/0x7e
[  561.670567]
               -> #1 (sk_lock-AF_BLUETOOTH-BTPROTO_ISO){+.+.}-{0:0}:
[  561.670571]        lock_acquire+0x7c/0xc0
[  561.670574]        lock_sock_nested+0x3b/0xf0
[  561.670577]        iso_sock_listen+0x2de/0xf30 [bluetooth]
[  561.670617]        __sys_listen_socket+0xef/0x130
[  561.670620]        __x64_sys_listen+0xe1/0x190
[  561.670623]        x64_sys_call+0x2517/0x25f0
[  561.670626]        do_syscall_64+0x87/0x150
[  561.670629]        entry_SYSCALL_64_after_hwframe+0x76/0x7e
[  561.670632]
               -> #0 (&hdev->lock){+.+.}-{3:3}:
[  561.670636]        __lock_acquire+0x32ad/0x6ab0
[  561.670639]        lock_acquire.part.0+0x118/0x360
[  561.670642]        lock_acquire+0x7c/0xc0
[  561.670644]        __mutex_lock+0x18d/0x12f0
[  561.670647]        mutex_lock_nested+0x1b/0x30
[  561.670651]        iso_conn_big_sync+0x73/0x260 [bluetooth]
[  561.670687]        iso_sock_recvmsg+0x3e9/0x500 [bluetooth]
[  561.670722]        sock_recvmsg+0x1d5/0x240
[  561.670725]        sock_read_iter+0x27d/0x470
[  561.670727]        vfs_read+0x9a0/0xd30
[  561.670731]        ksys_read+0x1a8/0x250
[  561.670733]        __x64_sys_read+0x72/0xc0
[  561.670736]        x64_sys_call+0x1b12/0x25f0
[  561.670738]        do_syscall_64+0x87/0x150
[  561.670741]        entry_SYSCALL_64_after_hwframe+0x76/0x7e
[  561.670744]
               other info that might help us debug this:

[  561.670745] Chain exists of:
&hdev->lock --> sk_lock-AF_BLUETOOTH-BTPROTO_ISO --> sk_lock-AF_BLUETOOTH

[  561.670751]  Possible unsafe locking scenario:

[  561.670753]        CPU0                    CPU1
[  561.670754]        ----                    ----
[  561.670756]   lock(sk_lock-AF_BLUETOOTH);
[  561.670758]                                lock(sk_lock
                                              AF_BLUETOOTH-BTPROTO_ISO);
[  561.670761]                                lock(sk_lock-AF_BLUETOOTH);
[  561.670764]   lock(&hdev->lock);
[  561.670767]
                *** DEADLOCK ***

Fixes: 07a9342b94a9 ("Bluetooth: ISO: Send BIG Create Sync via hci_sync")
Signed-off-by: Iulia Tanasescu <iulia.tanasescu@nxp.com>
---
 net/bluetooth/iso.c | 34 +++++++++++++++++++++++++++-------
 1 file changed, 27 insertions(+), 7 deletions(-)

diff --git a/net/bluetooth/iso.c b/net/bluetooth/iso.c
index ed559c82d353..44acddf58a0c 100644
--- a/net/bluetooth/iso.c
+++ b/net/bluetooth/iso.c
@@ -1447,6 +1447,7 @@ static void iso_conn_big_sync(struct sock *sk)
 	 * change.
 	 */
 	hci_dev_lock(hdev);
+	lock_sock(sk);
 
 	if (!test_and_set_bit(BT_SK_BIG_SYNC, &iso_pi(sk)->flags)) {
 		err = hci_le_big_create_sync(hdev, iso_pi(sk)->conn->hcon,
@@ -1459,6 +1460,7 @@ static void iso_conn_big_sync(struct sock *sk)
 				   err);
 	}
 
+	release_sock(sk);
 	hci_dev_unlock(hdev);
 }
 
@@ -1467,39 +1469,57 @@ static int iso_sock_recvmsg(struct socket *sock, struct msghdr *msg,
 {
 	struct sock *sk = sock->sk;
 	struct iso_pinfo *pi = iso_pi(sk);
+	bool early_ret = false;
+	int err = 0;
 
 	BT_DBG("sk %p", sk);
 
 	if (test_and_clear_bit(BT_SK_DEFER_SETUP, &bt_sk(sk)->flags)) {
+		sock_hold(sk);
 		lock_sock(sk);
+
 		switch (sk->sk_state) {
 		case BT_CONNECT2:
 			if (test_bit(BT_SK_PA_SYNC, &pi->flags)) {
+				release_sock(sk);
 				iso_conn_big_sync(sk);
+				lock_sock(sk);
+
 				sk->sk_state = BT_LISTEN;
 			} else {
 				iso_conn_defer_accept(pi->conn->hcon);
 				sk->sk_state = BT_CONFIG;
 			}
-			release_sock(sk);
-			return 0;
+
+			early_ret = true;
+			break;
 		case BT_CONNECTED:
 			if (test_bit(BT_SK_PA_SYNC, &iso_pi(sk)->flags)) {
+				release_sock(sk);
 				iso_conn_big_sync(sk);
+				lock_sock(sk);
+
 				sk->sk_state = BT_LISTEN;
-				release_sock(sk);
-				return 0;
+				early_ret = true;
 			}
 
-			release_sock(sk);
 			break;
 		case BT_CONNECT:
 			release_sock(sk);
-			return iso_connect_cis(sk);
+			err = iso_connect_cis(sk);
+			lock_sock(sk);
+
+			early_ret = true;
+			break;
 		default:
-			release_sock(sk);
 			break;
 		}
+
+		release_sock(sk);
+		sock_put(sk);
+
+		if (early_ret)
+			return err;
 	}
 
 	return bt_sock_recvmsg(sock, msg, len, flags);
-- 
2.43.0

RE: Bluetooth: iso: Fix circular lock warnings

[bluez.test.bot]

[-- Attachment #1: Type: text/plain, Size: 1680 bytes --]

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=915843

---Test result---

Test Summary:
CheckPatch                    PENDING   0.28 seconds
GitLint                       PENDING   0.21 seconds
SubjectPrefix                 PASS      0.23 seconds
BuildKernel                   PASS      25.78 seconds
CheckAllWarning               PASS      27.60 seconds
CheckSparse                   PASS      31.26 seconds
BuildKernel32                 PASS      25.38 seconds
TestRunnerSetup               PASS      439.26 seconds
TestRunner_l2cap-tester       PASS      20.54 seconds
TestRunner_iso-tester         PASS      27.79 seconds
TestRunner_bnep-tester        PASS      4.91 seconds
TestRunner_mgmt-tester        PASS      120.37 seconds
TestRunner_rfcomm-tester      PASS      7.56 seconds
TestRunner_sco-tester         PASS      9.29 seconds
TestRunner_ioctl-tester       PASS      8.06 seconds
TestRunner_mesh-tester        PASS      6.95 seconds
TestRunner_smp-tester         PASS      7.01 seconds
TestRunner_userchan-tester    PASS      4.98 seconds
IncrementalBuild              PENDING   0.90 seconds

Details
##############################
Test: CheckPatch - PENDING
Desc: Run checkpatch.pl script
Output:

##############################
Test: GitLint - PENDING
Desc: Run gitlint
Output:

##############################
Test: IncrementalBuild - PENDING
Desc: Incremental build with the patches in the series
Output:



---
Regards,
Linux Bluetooth

Re: [PATCH v2 0/2] Bluetooth: iso: Fix circular lock warnings

[patchwork-bot+bluetooth]

Hello:

This series was applied to bluetooth/bluetooth-next.git (master)
by Luiz Augusto von Dentz <luiz.von.dentz@intel.com>:

On Mon,  9 Dec 2024 11:42:16 +0200 you wrote:
> This patch fixes the circular locking dependency warnings in iso.c,
> caused by A->B/B->A type lock ordering with sk and hdev.
> 
> The first commit fixes the warning caused by iso_listen_bis, by
> releasing sk lock before entering the function and acquiring hdev
> lock.
> 
> [...]

Here is the summary with links:
  - [v2,1/2] Bluetooth: iso: Fix circular lock in iso_listen_bis
    https://git.kernel.org/bluetooth/bluetooth-next/c/c9f33b7cbdb3
  - [v2,2/2] Bluetooth: iso: Fix circular lock in iso_conn_big_sync
    https://git.kernel.org/bluetooth/bluetooth-next/c/ea4f8778d364

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html