From patchwork Fri May 31 01:04:24 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dan Williams X-Patchwork-Id: 13681016 X-Patchwork-Delegate: bhelgaas@google.com Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.9]) (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 E4B525C89; Fri, 31 May 2024 01:04:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.9 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717117466; cv=none; b=g8zEjIj8xSgdNOjD30Vzizr1RYGP28cjxkiXJOtpTeY4Nv39M7phjSg/5fmRRmSXMqg6T6PMDD98xEvCI2oLzrCk7HkAVaxn8I+aO2nIgUW6VRij7n1HPFoWbRIkoNn6DAxpquR3IoZ3rNx/TS8UIjBx8bWfW5CsJCPbKGnCgp8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717117466; c=relaxed/simple; bh=+LdGt45zsVS7JdFsVl1ozP8KsH9eR/q0DhdaeOHz2DU=; h=Subject:From:To:Cc:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=FsBvvRBs4VTpA6oO8FYa5pZPwlvUnNyjX7x+1SYNtn3x/akviHt0vmET/v8gK1Nm1hvx/UHAlFkO9iTWGR7jMKsr/YHzdcVBBvff9Ra+ALmExJg13UwbutkFFbLEWN3TpKgsMkeE7eTXQoXUuck6kMu4DzD///EMNZqh4l3ARIY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=T5TsMOT/; arc=none smtp.client-ip=192.198.163.9 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="T5TsMOT/" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1717117465; x=1748653465; h=subject:from:to:cc:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=+LdGt45zsVS7JdFsVl1ozP8KsH9eR/q0DhdaeOHz2DU=; b=T5TsMOT/pHD3Wx/Emnh0Zta+X3QcKM6rk/h8oV+MdHMjwHzUgFoRpMlO iUnLJMvzAIHyFSzp3+M2bsO5lZ48wN91Yraok7C5XOzgwMpNEvtep3qYJ Lirjf572gM4yLYHH0uMjW1zNfTyaMu7TFooo/berlwfXuZW+jAajjnp0A MfblRBZw8Ewkz2xt9qhagLC7zCMiwgH7n+B5nBEpjJeldQmWK1l23Zj9U GSKoykLaq4RiqIFWPn+IyqvZBPfh+NJ8/V2115hkKZhv21R9SpQau7qkL LeD0rIsfaSYAXexUNSsmxv/HZOcIBMe+3CDp6mmIPOPFIWAE1UGsnq0sN Q==; X-CSE-ConnectionGUID: qnwNw1f4SuKutl1jh3Biyw== X-CSE-MsgGUID: hUWHyUzeQwCUX/m949/hVQ== X-IronPort-AV: E=McAfee;i="6600,9927,11088"; a="24308759" X-IronPort-AV: E=Sophos;i="6.08,202,1712646000"; d="scan'208";a="24308759" Received: from orviesa007.jf.intel.com ([10.64.159.147]) by fmvoesa103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 May 2024 18:04:24 -0700 X-CSE-ConnectionGUID: vHfGvFrBT8KZkuWYRpOVow== X-CSE-MsgGUID: malWm3zjSGC8uDcUI7wIJg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.08,202,1712646000"; d="scan'208";a="36624081" Received: from spittala-mobl3.amr.corp.intel.com (HELO dwillia2-xfh.jf.intel.com) ([10.209.84.244]) by orviesa007-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 May 2024 18:04:25 -0700 Subject: [PATCH v2 1/3] PCI: Revert the cfg_access_lock lockdep mechanism From: Dan Williams To: bhelgaas@google.com Cc: Imre Deak , Jani Saarinen , Dave Jiang , linux-pci@vger.kernel.org, linux-cxl@vger.kernel.org Date: Thu, 30 May 2024 18:04:24 -0700 Message-ID: <171711746402.1628941.14575335981264103013.stgit@dwillia2-xfh.jf.intel.com> In-Reply-To: <171711745834.1628941.5259278474013108507.stgit@dwillia2-xfh.jf.intel.com> References: <171711745834.1628941.5259278474013108507.stgit@dwillia2-xfh.jf.intel.com> User-Agent: StGit/0.18-3-g996c Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 While the experiment did reveal that there are additional places that are missing the lock during secondary bus reset, one of the places that needs to take cfg_access_lock (pci_bus_lock()) is not prepared for lockdep annotation. Specifically, pci_bus_lock() takes pci_dev_lock() recursively and is currently dependent on the fact that the device_lock() is marked lockdep_set_novalidate_class(&dev->mutex). Otherwise, without that annotation, pci_bus_lock() would need to use something like a new pci_dev_lock_nested() helper, a scheme to track a PCI device's depth in the topology, and a hope that the depth of a PCI tree never exceeds the max value for a lockdep subclass. The alternative to ripping out the lockdep coverage would be to deploy a dynamic lock key for every PCI device. Unfortunately, there is evidence that increasing the number of keys that lockdep needs to track to be per-PCI-device is prohibitively expensive for something like the cfg_access_lock. The main motivation for adding the annotation in the first place was to catch unlocked secondary bus resets, not necessarily catch lock ordering problems between cfg_access_lock and other locks. Solve that narrower problem with follow-on patches, and just due to targeted revert for now. Fixes: 7e89efc6e9e4 ("PCI: Lock upstream bridge for pci_reset_function()") Reported-by: Imre Deak Closes: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_134186v1/shard-dg2-1/igt@device_reset@unbind-reset-rebind.html Cc: Jani Saarinen Cc: Dave Jiang Cc: Bjorn Helgaas Signed-off-by: Dan Williams Reviewed-by: Dave Jiang Tested-by: Kalle Valo Tested-by: Leon Romanovsky --- drivers/pci/access.c | 4 ---- drivers/pci/pci.c | 1 - drivers/pci/probe.c | 3 --- include/linux/lockdep.h | 5 ----- include/linux/pci.h | 2 -- 5 files changed, 15 deletions(-) diff --git a/drivers/pci/access.c b/drivers/pci/access.c index 30f031de9cfe..b123da16b63b 100644 --- a/drivers/pci/access.c +++ b/drivers/pci/access.c @@ -289,8 +289,6 @@ void pci_cfg_access_lock(struct pci_dev *dev) { might_sleep(); - lock_map_acquire(&dev->cfg_access_lock); - raw_spin_lock_irq(&pci_lock); if (dev->block_cfg_access) pci_wait_cfg(dev); @@ -345,8 +343,6 @@ void pci_cfg_access_unlock(struct pci_dev *dev) raw_spin_unlock_irqrestore(&pci_lock, flags); wake_up_all(&pci_cfg_wait); - - lock_map_release(&dev->cfg_access_lock); } EXPORT_SYMBOL_GPL(pci_cfg_access_unlock); diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 59e0949fb079..35fb1f17a589 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -4883,7 +4883,6 @@ void __weak pcibios_reset_secondary_bus(struct pci_dev *dev) */ int pci_bridge_secondary_bus_reset(struct pci_dev *dev) { - lock_map_assert_held(&dev->cfg_access_lock); pcibios_reset_secondary_bus(dev); return pci_bridge_wait_for_secondary_bus(dev, "bus reset"); diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 8e696e547565..5fbabb4e3425 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -2546,9 +2546,6 @@ void pci_device_add(struct pci_dev *dev, struct pci_bus *bus) dev->dev.dma_mask = &dev->dma_mask; dev->dev.dma_parms = &dev->dma_parms; dev->dev.coherent_dma_mask = 0xffffffffull; - lockdep_register_key(&dev->cfg_access_key); - lockdep_init_map(&dev->cfg_access_lock, dev_name(&dev->dev), - &dev->cfg_access_key, 0); dma_set_max_seg_size(&dev->dev, 65536); dma_set_seg_boundary(&dev->dev, 0xffffffff); diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h index 5e51b0de4c4b..08b0d1d9d78b 100644 --- a/include/linux/lockdep.h +++ b/include/linux/lockdep.h @@ -297,9 +297,6 @@ extern void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie); .wait_type_inner = _wait_type, \ .lock_type = LD_LOCK_WAIT_OVERRIDE, } -#define lock_map_assert_held(l) \ - lockdep_assert(lock_is_held(l) != LOCK_STATE_NOT_HELD) - #else /* !CONFIG_LOCKDEP */ static inline void lockdep_init_task(struct task_struct *task) @@ -391,8 +388,6 @@ extern int lockdep_is_held(const void *); #define DEFINE_WAIT_OVERRIDE_MAP(_name, _wait_type) \ struct lockdep_map __maybe_unused _name = {} -#define lock_map_assert_held(l) do { (void)(l); } while (0) - #endif /* !LOCKDEP */ #ifdef CONFIG_PROVE_LOCKING diff --git a/include/linux/pci.h b/include/linux/pci.h index fb004fd4e889..cafc5ab1cbcb 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -413,8 +413,6 @@ struct pci_dev { struct resource driver_exclusive_resource; /* driver exclusive resource ranges */ bool match_driver; /* Skip attaching driver */ - struct lock_class_key cfg_access_key; - struct lockdep_map cfg_access_lock; unsigned int transparent:1; /* Subtractive decode bridge */ unsigned int io_window:1; /* Bridge has I/O window */