Bluetooth: L2CAP: accept zero as a special value for MTU auto-selection

Commit Message

Fedor Pchelkin Jan. 28, 2025, 9:08 p.m. UTC

One of the possible ways to enable the input MTU auto-selection for L2CAP
connections is supposed to be through passing a special "0" value for it
as a socket option. Commit [1] added one of those into avdtp. However, it
simply wouldn't work because the kernel still treats the specified value
as invalid and denies the setting attempt. Recorded BlueZ logs include the
following: 

  bluetoothd[496]: profiles/audio/avdtp.c:l2cap_connect() setsockopt(L2CAP_OPTIONS): Invalid argument (22)

[1]: https://github.com/bluez/bluez/commit/ae5be371a9f53fed33d2b34748a95a5498fd4b77

Found by Linux Verification Center (linuxtesting.org).

Fixes: 4b6e228e297b ("Bluetooth: Auto tune if input MTU is set to 0")
Cc: [e-mail]
Signed-off-by: Fedor Pchelkin <[e-mail]>
---
 net/bluetooth/l2cap_sock.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

[e-mail] Jan. 28, 2025, 9:34 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=928934

---Test result---

Test Summary:
CheckPatch                    PENDING   0.36 seconds
GitLint                       PENDING   0.31 seconds
SubjectPrefix                 PASS      0.05 seconds
BuildKernel                   PASS      24.56 seconds
CheckAllWarning               PASS      27.01 seconds
CheckSparse                   PASS      30.93 seconds
BuildKernel32                 PASS      24.07 seconds
TestRunnerSetup               PASS      426.95 seconds
TestRunner_l2cap-tester       PASS      20.24 seconds
TestRunner_iso-tester         PASS      29.57 seconds
TestRunner_bnep-tester        PASS      4.81 seconds
TestRunner_mgmt-tester        FAIL      119.22 seconds
TestRunner_rfcomm-tester      PASS      7.49 seconds
TestRunner_sco-tester         PASS      9.37 seconds
TestRunner_ioctl-tester       PASS      8.12 seconds
TestRunner_mesh-tester        PASS      6.03 seconds
TestRunner_smp-tester         PASS      6.87 seconds
TestRunner_userchan-tester    PASS      5.00 seconds
IncrementalBuild              PENDING   0.51 seconds

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

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

##############################
Test: TestRunner_mgmt-tester - FAIL
Desc: Run mgmt-tester with test-runner
Output:
Total: 490, Passed: 482 (98.4%), Failed: 4, Not Run: 4

Failed Test Cases
LL Privacy - Add Device 3 (AL is full)               Failed       0.199 seconds
LL Privacy - Set Flags 1 (Add to RL)                 Failed       0.147 seconds
LL Privacy - Set Flags 3 (2 Devices to RL)           Failed       0.187 seconds
LL Privacy - Start Discovery 1 (Disable RL)          Failed       0.157 seconds
##############################
Test: IncrementalBuild - PENDING
Desc: Incremental build with the patches in the series
Output:



---
Regards,
Linux Bluetooth

[e-mail] Jan. 29, 2025, 8:20 p.m. UTC | #2

Hello:

This patch was applied to bluetooth/bluetooth-next.git (master)
by Luiz Augusto von Dentz <[e-mail]>:

On Wed, 29 Jan 2025 00:08:14 +0300 you wrote:
> One of the possible ways to enable the input MTU auto-selection for L2CAP
> connections is supposed to be through passing a special "0" value for it
> as a socket option. Commit [1] added one of those into avdtp. However, it
> simply wouldn't work because the kernel still treats the specified value
> as invalid and denies the setting attempt. Recorded BlueZ logs include the
> following:
> 
> [...]

Here is the summary with links:
  - Bluetooth: L2CAP: accept zero as a special value for MTU auto-selection
    https://git.kernel.org/bluetooth/bluetooth-next/c/257a2b95631f

You are awesome, thank you!

Patch

diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c
index 49f97d4138ea..46ea0bee2259 100644
--- a/net/bluetooth/l2cap_sock.c
+++ b/net/bluetooth/l2cap_sock.c
@@ -710,12 +710,12 @@  static bool l2cap_valid_mtu(struct l2cap_chan *chan, u16 mtu)
 {
 	switch (chan->scid) {
 	case L2CAP_CID_ATT:
-		if (mtu < L2CAP_LE_MIN_MTU)
+		if (mtu && mtu < L2CAP_LE_MIN_MTU)
 			return false;
 		break;
 
 	default:
-		if (mtu < L2CAP_DEFAULT_MIN_MTU)
+		if (mtu && mtu < L2CAP_DEFAULT_MIN_MTU)
 			return false;
 	}