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 9D26E1F95E for ; Tue, 23 Apr 2024 20:36:21 +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=1713904581; cv=none; b=ZcQnjaKxHpuJ/hcYPiKzCTwQUH/ybnQgMAVz0r1Fsl8IAJIrYB4w+bAcjAc3YborVxH8c2gPAOOPbcI5Z5HNWUawJCFFUDAbFneELV5/JbCecHJ2sFuidozpQ/pJ7porVYYMtBSHxLTb9ovEmv9rUkVqSZm6n/y23NyQpYbfV8Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713904581; c=relaxed/simple; bh=y8E9yAVYPm115SXNsPNii4IEfKzRkCHVvUcPHD3W8uU=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=isjAgTXVQj444LcLl+tjFWqaQXsxpATc2iDSyWT48iI2fz7UwBTdgNKRiSTBuJH0eamKzWQfg7EGGC2TLf4ZZRiMNkmvon9On0wcgwksgSHUuzF7yLlWaJV+NHn3OIxxLe/Ou+3NohULHtU+UBdQsIYRupBBWdIB6iYc3JjeUC8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=AccLvEu4; 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="AccLvEu4" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D3645C116B1; Tue, 23 Apr 2024 20:36:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1713904581; bh=y8E9yAVYPm115SXNsPNii4IEfKzRkCHVvUcPHD3W8uU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=AccLvEu4WiDQtkXwjOz4JW4lN/AQXEPgwWxncr9M9gfQEPXel4+ejt9bfL5nzMhgM UzyXHcWIq3FbVwU+4d0tKYs3/0mcIwCzENtV+mKKQQUK784gbymN6Trl3n8Yi+YsZz KRvZprDs27CN1OdRhidSypXjFYQ0ebaVg7PSbh6IhNPbXJWBuIQe5f6nAQKpxUTkQ/ 3ijuqW9WQuMA7dxv+npCGHDdW8Q0SE5DTuYBXcW+DITYjvQGY3UzTXHE8qXxOm4vUE yuxTlOR3ZoyGEjmWEj/udQXHhQFRdoL9+Mw4OvefAay1lX0W1RXlLQGPR9tM6NTH0/ GuYJlZi1xy1mA== From: Bjorn Helgaas To: stable@vger.kernel.org Cc: Johan Hovold , Bjorn Helgaas Subject: [PATCH 6.6.y] PCI/ASPM: Fix deadlock when enabling ASPM Date: Tue, 23 Apr 2024 15:36:11 -0500 Message-Id: <20240423203611.463084-1-helgaas@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <2024021328-stylus-ooze-f752@gregkh> References: <2024021328-stylus-ooze-f752@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Johan Hovold commit 1e560864159d002b453da42bd2c13a1805515a20 upstream. A last minute revert in 6.7-final introduced a potential deadlock when enabling ASPM during probe of Qualcomm PCIe controllers as reported by lockdep: ============================================ WARNING: possible recursive locking detected 6.7.0 #40 Not tainted -------------------------------------------- kworker/u16:5/90 is trying to acquire lock: ffffacfa78ced000 (pci_bus_sem){++++}-{3:3}, at: pcie_aspm_pm_state_change+0x58/0xdc but task is already holding lock: ffffacfa78ced000 (pci_bus_sem){++++}-{3:3}, at: pci_walk_bus+0x34/0xbc other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(pci_bus_sem); lock(pci_bus_sem); *** DEADLOCK *** Call trace: print_deadlock_bug+0x25c/0x348 __lock_acquire+0x10a4/0x2064 lock_acquire+0x1e8/0x318 down_read+0x60/0x184 pcie_aspm_pm_state_change+0x58/0xdc pci_set_full_power_state+0xa8/0x114 pci_set_power_state+0xc4/0x120 qcom_pcie_enable_aspm+0x1c/0x3c [pcie_qcom] pci_walk_bus+0x64/0xbc qcom_pcie_host_post_init_2_7_0+0x28/0x34 [pcie_qcom] The deadlock can easily be reproduced on machines like the Lenovo ThinkPad X13s by adding a delay to increase the race window during asynchronous probe where another thread can take a write lock. Add a new pci_set_power_state_locked() and associated helper functions that can be called with the PCI bus semaphore held to avoid taking the read lock twice. Link: https://lore.kernel.org/r/ZZu0qx2cmn7IwTyQ@hovoldconsulting.com Link: https://lore.kernel.org/r/20240130100243.11011-1-johan+linaro@kernel.org Fixes: f93e71aea6c6 ("Revert "PCI/ASPM: Remove pcie_aspm_pm_state_change()"") Signed-off-by: Johan Hovold [bhelgaas: backported to v6.6.y, which contains 8cc22ba3f77c ("Revert "PCI/ASPM: Remove pcie_aspm_pm_state_change()""), a backport of f93e71aea6c6. This omits the drivers/pci/controller/dwc/pcie-qcom.c hunk that updates qcom_pcie_enable_aspm(), which was added by 9f4f3dfad8cf ("PCI: qcom: Enable ASPM for platforms supporting 1.9.0 ops"), which is not present in v6.6.28.] Signed-off-by: Bjorn Helgaas --- drivers/pci/bus.c | 49 +++++++++++++++++--------- drivers/pci/pci.c | 78 +++++++++++++++++++++++++++-------------- drivers/pci/pci.h | 4 +-- drivers/pci/pcie/aspm.c | 13 ++++--- include/linux/pci.h | 5 +++ 5 files changed, 100 insertions(+), 49 deletions(-) diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c index 9c2137dae429..826b5016a101 100644 --- a/drivers/pci/bus.c +++ b/drivers/pci/bus.c @@ -386,21 +386,8 @@ void pci_bus_add_devices(const struct pci_bus *bus) } EXPORT_SYMBOL(pci_bus_add_devices); -/** pci_walk_bus - walk devices on/under bus, calling callback. - * @top bus whose devices should be walked - * @cb callback to be called for each device found - * @userdata arbitrary pointer to be passed to callback. - * - * Walk the given bus, including any bridged devices - * on buses under this bus. Call the provided callback - * on each device found. - * - * We check the return of @cb each time. If it returns anything - * other than 0, we break out. - * - */ -void pci_walk_bus(struct pci_bus *top, int (*cb)(struct pci_dev *, void *), - void *userdata) +static void __pci_walk_bus(struct pci_bus *top, int (*cb)(struct pci_dev *, void *), + void *userdata, bool locked) { struct pci_dev *dev; struct pci_bus *bus; @@ -408,7 +395,8 @@ void pci_walk_bus(struct pci_bus *top, int (*cb)(struct pci_dev *, void *), int retval; bus = top; - down_read(&pci_bus_sem); + if (!locked) + down_read(&pci_bus_sem); next = top->devices.next; for (;;) { if (next == &bus->devices) { @@ -431,10 +419,37 @@ void pci_walk_bus(struct pci_bus *top, int (*cb)(struct pci_dev *, void *), if (retval) break; } - up_read(&pci_bus_sem); + if (!locked) + up_read(&pci_bus_sem); +} + +/** + * pci_walk_bus - walk devices on/under bus, calling callback. + * @top: bus whose devices should be walked + * @cb: callback to be called for each device found + * @userdata: arbitrary pointer to be passed to callback + * + * Walk the given bus, including any bridged devices + * on buses under this bus. Call the provided callback + * on each device found. + * + * We check the return of @cb each time. If it returns anything + * other than 0, we break out. + */ +void pci_walk_bus(struct pci_bus *top, int (*cb)(struct pci_dev *, void *), void *userdata) +{ + __pci_walk_bus(top, cb, userdata, false); } EXPORT_SYMBOL_GPL(pci_walk_bus); +void pci_walk_bus_locked(struct pci_bus *top, int (*cb)(struct pci_dev *, void *), void *userdata) +{ + lockdep_assert_held(&pci_bus_sem); + + __pci_walk_bus(top, cb, userdata, true); +} +EXPORT_SYMBOL_GPL(pci_walk_bus_locked); + struct pci_bus *pci_bus_get(struct pci_bus *bus) { if (bus) diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 06fc6f532d6c..dddd30deea32 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -1291,6 +1291,7 @@ int pci_power_up(struct pci_dev *dev) /** * pci_set_full_power_state - Put a PCI device into D0 and update its state * @dev: PCI device to power up + * @locked: whether pci_bus_sem is held * * Call pci_power_up() to put @dev into D0, read from its PCI_PM_CTRL register * to confirm the state change, restore its BARs if they might be lost and @@ -1300,7 +1301,7 @@ int pci_power_up(struct pci_dev *dev) * to D0, it is more efficient to use pci_power_up() directly instead of this * function. */ -static int pci_set_full_power_state(struct pci_dev *dev) +static int pci_set_full_power_state(struct pci_dev *dev, bool locked) { u16 pmcsr; int ret; @@ -1336,7 +1337,7 @@ static int pci_set_full_power_state(struct pci_dev *dev) } if (dev->bus->self) - pcie_aspm_pm_state_change(dev->bus->self); + pcie_aspm_pm_state_change(dev->bus->self, locked); return 0; } @@ -1365,10 +1366,22 @@ void pci_bus_set_current_state(struct pci_bus *bus, pci_power_t state) pci_walk_bus(bus, __pci_dev_set_current_state, &state); } +static void __pci_bus_set_current_state(struct pci_bus *bus, pci_power_t state, bool locked) +{ + if (!bus) + return; + + if (locked) + pci_walk_bus_locked(bus, __pci_dev_set_current_state, &state); + else + pci_walk_bus(bus, __pci_dev_set_current_state, &state); +} + /** * pci_set_low_power_state - Put a PCI device into a low-power state. * @dev: PCI device to handle. * @state: PCI power state (D1, D2, D3hot) to put the device into. + * @locked: whether pci_bus_sem is held * * Use the device's PCI_PM_CTRL register to put it into a low-power state. * @@ -1379,7 +1392,7 @@ void pci_bus_set_current_state(struct pci_bus *bus, pci_power_t state) * 0 if device already is in the requested state. * 0 if device's power state has been successfully changed. */ -static int pci_set_low_power_state(struct pci_dev *dev, pci_power_t state) +static int pci_set_low_power_state(struct pci_dev *dev, pci_power_t state, bool locked) { u16 pmcsr; @@ -1433,29 +1446,12 @@ static int pci_set_low_power_state(struct pci_dev *dev, pci_power_t state) pci_power_name(state)); if (dev->bus->self) - pcie_aspm_pm_state_change(dev->bus->self); + pcie_aspm_pm_state_change(dev->bus->self, locked); return 0; } -/** - * pci_set_power_state - Set the power state of a PCI device - * @dev: PCI device to handle. - * @state: PCI power state (D0, D1, D2, D3hot) to put the device into. - * - * Transition a device to a new power state, using the platform firmware and/or - * the device's PCI PM registers. - * - * RETURN VALUE: - * -EINVAL if the requested state is invalid. - * -EIO if device does not support PCI PM or its PM capabilities register has a - * wrong version, or device doesn't support the requested state. - * 0 if the transition is to D1 or D2 but D1 and D2 are not supported. - * 0 if device already is in the requested state. - * 0 if the transition is to D3 but D3 is not supported. - * 0 if device's power state has been successfully changed. - */ -int pci_set_power_state(struct pci_dev *dev, pci_power_t state) +static int __pci_set_power_state(struct pci_dev *dev, pci_power_t state, bool locked) { int error; @@ -1479,7 +1475,7 @@ int pci_set_power_state(struct pci_dev *dev, pci_power_t state) return 0; if (state == PCI_D0) - return pci_set_full_power_state(dev); + return pci_set_full_power_state(dev, locked); /* * This device is quirked not to be put into D3, so don't put it in @@ -1493,16 +1489,16 @@ int pci_set_power_state(struct pci_dev *dev, pci_power_t state) * To put the device in D3cold, put it into D3hot in the native * way, then put it into D3cold using platform ops. */ - error = pci_set_low_power_state(dev, PCI_D3hot); + error = pci_set_low_power_state(dev, PCI_D3hot, locked); if (pci_platform_power_transition(dev, PCI_D3cold)) return error; /* Powering off a bridge may power off the whole hierarchy */ if (dev->current_state == PCI_D3cold) - pci_bus_set_current_state(dev->subordinate, PCI_D3cold); + __pci_bus_set_current_state(dev->subordinate, PCI_D3cold, locked); } else { - error = pci_set_low_power_state(dev, state); + error = pci_set_low_power_state(dev, state, locked); if (pci_platform_power_transition(dev, state)) return error; @@ -1510,8 +1506,38 @@ int pci_set_power_state(struct pci_dev *dev, pci_power_t state) return 0; } + +/** + * pci_set_power_state - Set the power state of a PCI device + * @dev: PCI device to handle. + * @state: PCI power state (D0, D1, D2, D3hot) to put the device into. + * + * Transition a device to a new power state, using the platform firmware and/or + * the device's PCI PM registers. + * + * RETURN VALUE: + * -EINVAL if the requested state is invalid. + * -EIO if device does not support PCI PM or its PM capabilities register has a + * wrong version, or device doesn't support the requested state. + * 0 if the transition is to D1 or D2 but D1 and D2 are not supported. + * 0 if device already is in the requested state. + * 0 if the transition is to D3 but D3 is not supported. + * 0 if device's power state has been successfully changed. + */ +int pci_set_power_state(struct pci_dev *dev, pci_power_t state) +{ + return __pci_set_power_state(dev, state, false); +} EXPORT_SYMBOL(pci_set_power_state); +int pci_set_power_state_locked(struct pci_dev *dev, pci_power_t state) +{ + lockdep_assert_held(&pci_bus_sem); + + return __pci_set_power_state(dev, state, true); +} +EXPORT_SYMBOL(pci_set_power_state_locked); + #define PCI_EXP_SAVE_REGS 7 static struct pci_cap_saved_state *_pci_find_saved_cap(struct pci_dev *pci_dev, diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h index 1b4f94182972..2cc032e8cbb9 100644 --- a/drivers/pci/pci.h +++ b/drivers/pci/pci.h @@ -561,12 +561,12 @@ int pcie_retrain_link(struct pci_dev *pdev, bool use_lt); #ifdef CONFIG_PCIEASPM void pcie_aspm_init_link_state(struct pci_dev *pdev); void pcie_aspm_exit_link_state(struct pci_dev *pdev); -void pcie_aspm_pm_state_change(struct pci_dev *pdev); +void pcie_aspm_pm_state_change(struct pci_dev *pdev, bool locked); void pcie_aspm_powersave_config_link(struct pci_dev *pdev); #else static inline void pcie_aspm_init_link_state(struct pci_dev *pdev) { } static inline void pcie_aspm_exit_link_state(struct pci_dev *pdev) { } -static inline void pcie_aspm_pm_state_change(struct pci_dev *pdev) { } +static inline void pcie_aspm_pm_state_change(struct pci_dev *pdev, bool locked) { } static inline void pcie_aspm_powersave_config_link(struct pci_dev *pdev) { } #endif diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c index 7e3b342215e5..cde1a5a63943 100644 --- a/drivers/pci/pcie/aspm.c +++ b/drivers/pci/pcie/aspm.c @@ -1001,8 +1001,11 @@ void pcie_aspm_exit_link_state(struct pci_dev *pdev) up_read(&pci_bus_sem); } -/* @pdev: the root port or switch downstream port */ -void pcie_aspm_pm_state_change(struct pci_dev *pdev) +/* + * @pdev: the root port or switch downstream port + * @locked: whether pci_bus_sem is held + */ +void pcie_aspm_pm_state_change(struct pci_dev *pdev, bool locked) { struct pcie_link_state *link = pdev->link_state; @@ -1012,12 +1015,14 @@ void pcie_aspm_pm_state_change(struct pci_dev *pdev) * Devices changed PM state, we should recheck if latency * meets all functions' requirement */ - down_read(&pci_bus_sem); + if (!locked) + down_read(&pci_bus_sem); mutex_lock(&aspm_lock); pcie_update_aspm_capable(link->root); pcie_config_aspm_path(link); mutex_unlock(&aspm_lock); - up_read(&pci_bus_sem); + if (!locked) + up_read(&pci_bus_sem); } void pcie_aspm_powersave_config_link(struct pci_dev *pdev) diff --git a/include/linux/pci.h b/include/linux/pci.h index b548d5646a86..ee89a69817aa 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -1391,6 +1391,7 @@ int pci_load_and_free_saved_state(struct pci_dev *dev, struct pci_saved_state **state); int pci_platform_power_transition(struct pci_dev *dev, pci_power_t state); int pci_set_power_state(struct pci_dev *dev, pci_power_t state); +int pci_set_power_state_locked(struct pci_dev *dev, pci_power_t state); pci_power_t pci_choose_state(struct pci_dev *dev, pm_message_t state); bool pci_pme_capable(struct pci_dev *dev, pci_power_t state); void pci_pme_active(struct pci_dev *dev, bool enable); @@ -1594,6 +1595,8 @@ int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max, void pci_walk_bus(struct pci_bus *top, int (*cb)(struct pci_dev *, void *), void *userdata); +void pci_walk_bus_locked(struct pci_bus *top, int (*cb)(struct pci_dev *, void *), + void *userdata); int pci_cfg_space_size(struct pci_dev *dev); unsigned char pci_bus_max_busnr(struct pci_bus *bus); void pci_setup_bridge(struct pci_bus *bus); @@ -1990,6 +1993,8 @@ static inline int pci_save_state(struct pci_dev *dev) { return 0; } static inline void pci_restore_state(struct pci_dev *dev) { } static inline int pci_set_power_state(struct pci_dev *dev, pci_power_t state) { return 0; } +static inline int pci_set_power_state_locked(struct pci_dev *dev, pci_power_t state) +{ return 0; } static inline int pci_wake_from_d3(struct pci_dev *dev, bool enable) { return 0; } static inline pci_power_t pci_choose_state(struct pci_dev *dev, -- 2.34.1