From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E61ED29A2; Mon, 4 Aug 2025 00:27:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754267236; cv=none; b=d6y38skrlN6VCX1DFNfhoqXuweu9ROag32ByUVoGtT+btYMRchrxaCQWj5JkTlDkEh02avPrF78vjgRYVmjkMsKRgJRFJJdk+CwN/zmwtdzb5ZC37a1DUdtvfSTB8AgZ/BumTksmVSTwVwgBsyh66iaEXq7EAn4wNuwG7F7qVlQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754267236; c=relaxed/simple; bh=bfLHrI+KHBL420kB9LvWPzH5vg3kP5L2x0mod4WtyLQ=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=Bl8HqAKMpXsYgjlyEFhdDWRhiaJd6iZ70dom7PjKf1TtJKfluU9UwMBJlPb0D25dNfBIJ4P+ma6oCsCJVOBpTwukmB31oznW60qI7glEtEbuZP/Z2BI1/Pe3t/PNAMAtPOOEMkxSWalPl3eXzYV0zdL6dq/KpdlxA5av+Kl92o0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=vCz1pFdK; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="vCz1pFdK" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 595CBC4CEEB; Mon, 4 Aug 2025 00:27:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1754267235; bh=bfLHrI+KHBL420kB9LvWPzH5vg3kP5L2x0mod4WtyLQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=vCz1pFdKep/vbP6kNZC4csa2RpxO1qUhal+fqT2nUH7aNloimtXucmSQWCGSgBHvV 640qb9rLhASbiWJo2ni/MUw+FyPMSg3b1G66jgqA9RwMavyYtuxXso9W/rpVeHHoMv rKHTG0HWdM+WF3rMy4qo6uD+Ba2zVGb7Id3DhlUNV8J1UupPzve/WpJNxfGlQo0k/U /641xP96c5Sk4TLAeE/NJyGDyn2daHFG3sQhLSt/yGGVviKFJxBRkuJPsbCu8fs0Hv XK8OS5ry4GKpaMwvRNHYTVpvE7i2CDOSDuQDfhXi14Figrnls+JMqUvB+eLIVXVRld Lx8+mb5L9C2cg== From: Sasha Levin To: patches@lists.linux.dev, stable@vger.kernel.org Cc: Radhey Shyam Pandey , Thinh Nguyen , Greg Kroah-Hartman , Sasha Levin , michal.simek@amd.com, linux-usb@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: [PATCH AUTOSEL 6.16 74/85] usb: dwc3: xilinx: add shutdown callback Date: Sun, 3 Aug 2025 20:23:23 -0400 Message-Id: <20250804002335.3613254-74-sashal@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250804002335.3613254-1-sashal@kernel.org> References: <20250804002335.3613254-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 6.16 Content-Transfer-Encoding: 8bit From: Radhey Shyam Pandey [ Upstream commit 70627bf82e36e61c40c3315e1206e4ea4c02e668 ] Adds a shutdown callback to ensure that the XHCI stack is properly shutdown in reboot/shutdown path. In kexec flow, kernel_restart_prepare() performs actions necessary to prepare the system for a restart and invokes device_shutdown. To ensure proper shutdown attach the dwc3 shutdown implementation which mirrors the remove method. $ kexec -e xhci-hcd xhci-hcd.0.auto: remove, state 1 usb usb1: USB disconnect, device number 1 usb 1-1: USB disconnect, device number 6 xhci-hcd xhci-hcd.0.auto: USB bus 1 deregistered kexec_core: Starting new kernel Signed-off-by: Radhey Shyam Pandey Acked-by: Thinh Nguyen Link: https://lore.kernel.org/r/1748977771-714153-1-git-send-email-radhey.shyam.pandey@amd.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- LLM Generated explanations, may be completely bogus: **Backport Status: YES** This commit should be backported to stable kernel trees. Here's my detailed analysis: ## Analysis of the Commit ### 1. **Bug Fix Nature** This commit fixes a real bug where the USB XHCI stack is not properly shut down during kexec operations. The commit message explicitly shows the issue - when `kexec -e` is executed, the XHCI controller is removed but without a proper shutdown sequence, which can lead to: - Memory corruption if the controller continues DMA operations - System instability during kexec transitions - Potential crashes after kexec ### 2. **Simple and Contained Fix** The code change is minimal and low-risk: ```diff + .shutdown = dwc3_xlnx_remove, ``` It simply reuses the existing `dwc3_xlnx_remove` function as the shutdown callback. This is a common pattern in kernel drivers. ### 3. **Follows Established Pattern** My analysis shows this follows an established pattern in the dwc3 driver family: - `dwc3-of-simple.c` uses its remove function for shutdown - `dwc3-rtk.c` has a dedicated shutdown function that calls similar cleanup - The recent Tegra XUSB commit (3a3be3a1ebf0) added a shutdown callback for similar reasons (preventing SMMU-related crashes) ### 4. **Clear Side Effects** The `dwc3_xlnx_remove` function performs standard cleanup: - Depopulates child devices (`of_platform_depopulate`) - Disables and unprepares clocks - Manages runtime PM state These are all safe operations for shutdown context. ### 5. **Meets Stable Criteria** - **Fixes a real bug**: Prevents potential system instability during kexec - **Small change**: Single line addition - **Low risk**: Reuses existing, tested code path - **No new features**: Pure bug fix - **Clear benefit**: Improves system reliability during reboot/kexec operations ### 6. **Similar Issues in Other Drivers** The pattern of missing shutdown callbacks causing issues during kexec/reboot is well-documented in the kernel, particularly for devices that perform DMA operations. The fix ensures proper hardware shutdown sequence during system reboot/shutdown, preventing the USB controller from accessing memory after the system has started transitioning to a new kernel or shutting down. This is especially important for systems using kexec for fast reboots or crash dump collection. drivers/usb/dwc3/dwc3-xilinx.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/usb/dwc3/dwc3-xilinx.c b/drivers/usb/dwc3/dwc3-xilinx.c index 4ca7f6240d07..09c3c5c226ab 100644 --- a/drivers/usb/dwc3/dwc3-xilinx.c +++ b/drivers/usb/dwc3/dwc3-xilinx.c @@ -422,6 +422,7 @@ static const struct dev_pm_ops dwc3_xlnx_dev_pm_ops = { static struct platform_driver dwc3_xlnx_driver = { .probe = dwc3_xlnx_probe, .remove = dwc3_xlnx_remove, + .shutdown = dwc3_xlnx_remove, .driver = { .name = "dwc3-xilinx", .of_match_table = dwc3_xlnx_of_match, -- 2.39.5