netdev - [PATCH 2/2] Bluetooth: Do not set cur_adv_instance in adv param MGMT request

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Message-Id: <20210405162905.2.Iaac4fb40841e46f9ab815bffee439c91e44f0639@changeid>
Date:   Mon,  5 Apr 2021 16:33:05 -0700
From:   Daniel Winkler <danielwinkler@...gle.com>
To:     marcel@...tmann.org, linux-bluetooth@...r.kernel.org
Cc:     chromeos-bluetooth-upstreaming@...omium.org,
        Daniel Winkler <danielwinkler@...gle.com>,
        Miao-chen Chou <mcchou@...omium.org>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Johan Hedberg <johan.hedberg@...il.com>,
        Luiz Augusto von Dentz <luiz.dentz@...il.com>,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Subject: [PATCH 2/2] Bluetooth: Do not set cur_adv_instance in adv param MGMT request

We set hdev->cur_adv_instance in the adv param MGMT request to allow the
callback to the hci param request to set the tx power to the correct
instance. Now that the callbacks use the advertising handle from the hci
request (as they should), this workaround is no longer necessary.

Furthermore, this change resolves a race condition that is more
prevalent when using the extended advertising MGMT calls - if
hdev->cur_adv_instance is set in the params request, then when the data
request is called, we believe our new instance is already active. This
treats it as an update and immediately schedules the instance with the
controller, which has a potential race with the software rotation adv
update. By not setting hdev->cur_adv_instance too early, the new
instance is queued as it should be, to be used when the rotation comes
around again.

This change is tested on harrison peak to confirm that it resolves the
race condition on registration, and that there is no regression in
single- and multi-advertising automated tests.

Reviewed-by: Miao-chen Chou <mcchou@...omium.org>
Signed-off-by: Daniel Winkler <danielwinkler@...gle.com>
---

 net/bluetooth/mgmt.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/net/bluetooth/mgmt.c b/net/bluetooth/mgmt.c
index 09e099c419f251..59f8016c486626 100644
--- a/net/bluetooth/mgmt.c
+++ b/net/bluetooth/mgmt.c
@@ -7979,7 +7979,6 @@ static int add_ext_adv_params(struct sock *sk, struct hci_dev *hdev,
 		goto unlock;
 	}

-	hdev->cur_adv_instance = cp->instance;
 	/* Submit request for advertising params if ext adv available */
 	if (ext_adv_capable(hdev)) {
 		hci_req_init(&req, hdev);
-- 
2.31.0.208.g409f899ff0-goog