From 0f50a49e3008597abed0fff052d487f77db89093 Mon Sep 17 00:00:00 2001 From: Bjorn Helgaas Date: Fri, 15 Sep 2017 01:33:51 -0500 Subject: [PATCH] Revert "PCI: Avoid race while enabling upstream bridges" This reverts commit 40f11adc7cd9281227f0a6a627d966dd0a5f0cd9. Jens found that iwlwifi firmware loading failed on a Lenovo X1 Carbon, gen4: iwlwifi 0000:04:00.0: Direct firmware load for iwlwifi-8000C-34.ucode failed with error -2 iwlwifi 0000:04:00.0: Direct firmware load for iwlwifi-8000C-33.ucode failed with error -2 iwlwifi 0000:04:00.0: Direct firmware load for iwlwifi-8000C-32.ucode failed with error -2 iwlwifi 0000:04:00.0: loaded firmware version 31.532993.0 op_mode iwlmvm iwlwifi 0000:04:00.0: Detected Intel(R) Dual Band Wireless AC 8260, REV=0x208 ... iwlwifi 0000:04:00.0: Failed to load firmware chunk! iwlwifi 0000:04:00.0: Could not load the [0] uCode section iwlwifi 0000:04:00.0: Failed to start INIT ucode: -110 iwlwifi 0000:04:00.0: Failed to run INIT ucode: -110 He bisected it to 40f11adc7cd9 ("PCI: Avoid race while enabling upstream bridges"). Revert that commit to fix the regression. Link: http://lkml.kernel.org/r/4bcbcbc1-7c79-09f0-5071-bc2f53bf6574@kernel.dk Fixes: 40f11adc7cd9 ("PCI: Avoid race while enabling upstream bridges") Signed-off-by: Bjorn Helgaas CC: Srinath Mannam CC: Jens Axboe CC: Luca Coelho CC: Johannes Berg CC: Emmanuel Grumbach --- drivers/pci/pci.c | 13 ++----------- 1 file changed, 2 insertions(+), 11 deletions(-) diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index b0002daa50f3..6078dfc11b11 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -52,7 +52,6 @@ static void pci_pme_list_scan(struct work_struct *work); static LIST_HEAD(pci_pme_list); static DEFINE_MUTEX(pci_pme_list_mutex); static DECLARE_DELAYED_WORK(pci_pme_work, pci_pme_list_scan); -static DEFINE_MUTEX(pci_bridge_mutex); struct pci_pme_device { struct list_head list; @@ -1351,16 +1350,10 @@ static void pci_enable_bridge(struct pci_dev *dev) if (bridge) pci_enable_bridge(bridge); - /* - * Hold pci_bridge_mutex to prevent a race when enabling two - * devices below the bridge simultaneously. The race may cause a - * PCI_COMMAND_MEMORY update to be lost (see changelog). - */ - mutex_lock(&pci_bridge_mutex); if (pci_is_enabled(dev)) { if (!dev->is_busmaster) pci_set_master(dev); - goto end; + return; } retval = pci_enable_device(dev); @@ -1368,8 +1361,6 @@ static void pci_enable_bridge(struct pci_dev *dev) dev_err(&dev->dev, "Error enabling bridge (%d), continuing\n", retval); pci_set_master(dev); -end: - mutex_unlock(&pci_bridge_mutex); } static int pci_enable_device_flags(struct pci_dev *dev, unsigned long flags) @@ -1394,7 +1385,7 @@ static int pci_enable_device_flags(struct pci_dev *dev, unsigned long flags) return 0; /* already enabled */ bridge = pci_upstream_bridge(dev); - if (bridge && !pci_is_enabled(bridge)) + if (bridge) pci_enable_bridge(bridge); /* only skip sriov related */ -- 2.20.1