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 6C95C15A8; Mon, 4 Aug 2025 00:42:59 +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=1754268179; cv=none; b=JW6MJR8UquCXli+vFjpO5lbgOu99j78h/9Xr1jYpW+jlOaOR12J+J9hg8U6ikGEYhoVu4smw1Qc5xplvAtC1WCvhRdbk7CXMlnurv87QJmcU3SRIJksKNSvf7PPJwpRgdcrYIpPl3dhbP70piyRlFBuOTkhi6Y3o8JKwx5o9vP8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754268179; c=relaxed/simple; bh=Ocw9mSuJmrBghlUl0i7EmtkvcRwW95PrxHa/ffOmmnw=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=em0tsEM+VokcUAcN2lhFLts6WvZys7gqDpgcyd1rIO6x6PZOyYQidJOqkVMxfzodV1eoQbZB8HN6ulSggatG+NPmhRFJa+gy6KvIkJu6Qq+8nqv3G68D7Evd0uY3uckUhBpZTahLEJ+wvZJEfbAtnmPoWfWxPVftuQg9YKpMQGg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=B1JPy556; 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="B1JPy556" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 13D81C4CEEB; Mon, 4 Aug 2025 00:42:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1754268179; bh=Ocw9mSuJmrBghlUl0i7EmtkvcRwW95PrxHa/ffOmmnw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=B1JPy556GXDZpG+78NzMXJjbAxQlBYPgQTtmrSGuRYJZgaHsCFoYpVGeJ8ogcCMnl go+mR49TBaR4OUCXTVCbfX1FPOzio163pZfFR5PPkDvMIDnleK5OcWygyXYk9J9JuO QFdOJvRfaSWNsSGBi8Lt/nTK5YNzpF7/O1w5Bjq4WgK3zsbrUQ0XwN8lHa03mSAzP/ WURy2kI4Nm5H5hDoT2x7RebMF6EHlJ177wEy47VZy6ZXHjBFOsjs8VZyy+4saTzzHa 8o7Ec++oHUExmpfyP6HE4XWTlOHPQ4Cw3R9vdo6zLoyzEJTV9Y3w6d8e6N1ogaW4h2 W0VJFWImkFnhA== From: Sasha Levin To: patches@lists.linux.dev, stable@vger.kernel.org Cc: "Rafael J. Wysocki" , Ulf Hansson , Sasha Levin , rafael@kernel.org, linux-pm@vger.kernel.org Subject: [PATCH AUTOSEL 5.4 14/28] PM: runtime: Clear power.needs_force_resume in pm_runtime_reinit() Date: Sun, 3 Aug 2025 20:42:13 -0400 Message-Id: <20250804004227.3630243-14-sashal@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250804004227.3630243-1-sashal@kernel.org> References: <20250804004227.3630243-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 5.4.296 Content-Transfer-Encoding: 8bit From: "Rafael J. Wysocki" [ Upstream commit 89d9cec3b1e9c49bae9375a2db6dc49bc7468af0 ] Clear power.needs_force_resume in pm_runtime_reinit() in case it has been set by pm_runtime_force_suspend() invoked from a driver remove callback. Suggested-by: Ulf Hansson Signed-off-by: Rafael J. Wysocki Reviewed-by: Ulf Hansson Link: https://patch.msgid.link/9495163.CDJkKcVGEf@rjwysocki.net Signed-off-by: Sasha Levin --- LLM Generated explanations, may be completely bogus: **Backport Status: YES** This commit is a clear bugfix that should be backported to stable kernel trees for the following reasons: 1. **It fixes a real bug**: The commit addresses a specific issue where `power.needs_force_resume` flag is not cleared in `pm_runtime_reinit()` when a device is removed. If a driver calls `pm_runtime_force_suspend()` from its remove callback (which sets `needs_force_resume = 1`), this flag remains set even after the device is removed and potentially re-probed. 2. **The fix is minimal and contained**: The change adds just 5 lines of code (including comments) to clear a single flag. The modification is: ```c dev->power.needs_force_resume = false; ``` This is a very low-risk change that only affects the specific condition being fixed. 3. **It prevents state leakage**: Looking at the code flow: - `pm_runtime_force_suspend()` sets `dev->power.needs_force_resume = 1` (line in runtime.c) - When a driver is removed, `pm_runtime_remove()` calls `pm_runtime_reinit()` - Without this fix, if the device is re-probed, it would still have `needs_force_resume = 1` from the previous instance - This could lead to incorrect PM runtime behavior where `pm_runtime_force_resume()` would incorrectly think it needs to resume a device that was never suspended in the current probe cycle 4. **Related to previous stable fixes**: The git history shows a previous commit `c745253e2a69` ("PM: runtime: Fix unpaired parent child_count for force_resume") was already marked for stable (4.16+), indicating that issues with the `needs_force_resume` flag have been problematic enough to warrant stable backports. 5. **Clear bug scenario**: The commit message describes a specific scenario where this happens - when `pm_runtime_force_suspend()` is called from a driver remove callback. This is a legitimate use case where drivers want to ensure devices are suspended before removal. 6. **No architectural changes**: This is purely a bugfix that clears a flag that should have been cleared during reinitialization. It doesn't introduce new features or change any APIs. The fix ensures proper PM runtime state management across device removal and re-probing cycles, which is important for system stability and correct power management behavior. drivers/base/power/runtime.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c index 7fa231076ad5..7d362b38f2e8 100644 --- a/drivers/base/power/runtime.c +++ b/drivers/base/power/runtime.c @@ -1698,6 +1698,11 @@ void pm_runtime_reinit(struct device *dev) pm_runtime_put(dev->parent); } } + /* + * Clear power.needs_force_resume in case it has been set by + * pm_runtime_force_suspend() invoked from a driver remove callback. + */ + dev->power.needs_force_resume = false; } /** -- 2.39.5