linux-kernel - [PATCH 2/5] drivers/thunderbolt: don't resume switches without uid set

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Message-ID: <20220302220709.3138846-2-mario.limonciello@amd.com>
Date:   Wed, 2 Mar 2022 16:07:06 -0600
From:   Mario Limonciello <mario.limonciello@....com>
To:     Mika Westerberg <mika.westerberg@...ux.intel.com>
CC:     "open list:THUNDERBOLT DRIVER" <linux-usb@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <Sanju.Mehta@....com>,
        Mario Limonciello <mario.limonciello@....com>
Subject: [PATCH 2/5] drivers/thunderbolt: don't resume switches without uid set

Switches might not have a uid set if the DROM read failed during
initialization previously.

Normally upon resume the uid is re-read to confirm it's the same
device connected.
* If the DROM read failed during init but then succeeded during
  resume it could either be a new device or faulty device
* If the DROM read failed during init and also failed during resume
  it might be a different device plugged in all together.

Detect this situation and prevent re-using the same configuration in
these cirucmstances.

Signed-off-by: Mario Limonciello <mario.limonciello@....com>
---
 drivers/thunderbolt/switch.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/thunderbolt/switch.c b/drivers/thunderbolt/switch.c
index b5fb3e76ed09..294518af4ee4 100644
--- a/drivers/thunderbolt/switch.c
+++ b/drivers/thunderbolt/switch.c
@@ -2980,6 +2980,10 @@ int tb_switch_resume(struct tb_switch *sw)
 			return err;
 		}

+		/* We don't have any way to confirm this was the same device */
+		if (!sw->uid)
+			return -ENODEV;
+
 		if (tb_switch_is_usb4(sw))
 			err = usb4_switch_read_uid(sw, &uid);
 		else
-- 
2.34.1