From: Sergey Miroshnichenko <s.miroshnichenko@yadro.com>
To: <linux-pci@vger.kernel.org>, <linuxppc-dev@lists.ozlabs.org>
Cc: Bjorn Helgaas <helgaas@kernel.org>, <linux@yadro.com>,
Sergey Miroshnichenko <s.miroshnichenko@yadro.com>
Subject: [PATCH RFC v4 02/21] PCI: Fix race condition in pci_enable/disable_device()
Date: Mon, 11 Mar 2019 16:31:03 +0300 [thread overview]
Message-ID: <20190311133122.11417-3-s.miroshnichenko@yadro.com> (raw)
In-Reply-To: <20190311133122.11417-1-s.miroshnichenko@yadro.com>
CPU0 CPU1
pci_enable_device_mem() pci_enable_device_mem()
pci_enable_bridge() pci_enable_bridge()
pci_is_enabled()
return false;
atomic_inc_return(enable_cnt)
Start actual enabling the bridge
... pci_is_enabled()
... return true;
... Start memory requests <-- FAIL
...
Set the PCI_COMMAND_MEMORY bit <-- Must wait for this
This patch protects the pci_enable/disable_device() and pci_enable_bridge()
with mutexes.
Signed-off-by: Sergey Miroshnichenko <s.miroshnichenko@yadro.com>
---
drivers/pci/pci.c | 26 ++++++++++++++++++++++----
drivers/pci/probe.c | 1 +
include/linux/pci.h | 1 +
3 files changed, 24 insertions(+), 4 deletions(-)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index f006068be209..895201d4c9e6 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1615,6 +1615,8 @@ static void pci_enable_bridge(struct pci_dev *dev)
struct pci_dev *bridge;
int retval;
+ mutex_lock(&dev->enable_mutex);
+
bridge = pci_upstream_bridge(dev);
if (bridge)
pci_enable_bridge(bridge);
@@ -1622,6 +1624,7 @@ static void pci_enable_bridge(struct pci_dev *dev)
if (pci_is_enabled(dev)) {
if (!dev->is_busmaster)
pci_set_master(dev);
+ mutex_unlock(&dev->enable_mutex);
return;
}
@@ -1630,11 +1633,14 @@ static void pci_enable_bridge(struct pci_dev *dev)
pci_err(dev, "Error enabling bridge (%d), continuing\n",
retval);
pci_set_master(dev);
+ mutex_unlock(&dev->enable_mutex);
}
static int pci_enable_device_flags(struct pci_dev *dev, unsigned long flags)
{
struct pci_dev *bridge;
+ /* Enable-locking of bridges is performed within the pci_enable_bridge() */
+ bool need_lock = !dev->subordinate;
int err;
int i, bars = 0;
@@ -1650,8 +1656,13 @@ static int pci_enable_device_flags(struct pci_dev *dev, unsigned long flags)
dev->current_state = (pmcsr & PCI_PM_CTRL_STATE_MASK);
}
- if (atomic_inc_return(&dev->enable_cnt) > 1)
+ if (need_lock)
+ mutex_lock(&dev->enable_mutex);
+ if (pci_is_enabled(dev)) {
+ if (need_lock)
+ mutex_unlock(&dev->enable_mutex);
return 0; /* already enabled */
+ }
bridge = pci_upstream_bridge(dev);
if (bridge)
@@ -1666,8 +1677,10 @@ static int pci_enable_device_flags(struct pci_dev *dev, unsigned long flags)
bars |= (1 << i);
err = do_pci_enable_device(dev, bars);
- if (err < 0)
- atomic_dec(&dev->enable_cnt);
+ if (err >= 0)
+ atomic_inc(&dev->enable_cnt);
+ if (need_lock)
+ mutex_unlock(&dev->enable_mutex);
return err;
}
@@ -1910,15 +1923,20 @@ void pci_disable_device(struct pci_dev *dev)
if (dr)
dr->enabled = 0;
+ mutex_lock(&dev->enable_mutex);
dev_WARN_ONCE(&dev->dev, atomic_read(&dev->enable_cnt) <= 0,
"disabling already-disabled device");
- if (atomic_dec_return(&dev->enable_cnt) != 0)
+ if (atomic_dec_return(&dev->enable_cnt) != 0) {
+ mutex_unlock(&dev->enable_mutex);
return;
+ }
do_pci_disable_device(dev);
dev->is_busmaster = 0;
+
+ mutex_unlock(&dev->enable_mutex);
}
EXPORT_SYMBOL(pci_disable_device);
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 2ec0df04e0dc..977a127ce791 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -2267,6 +2267,7 @@ struct pci_dev *pci_alloc_dev(struct pci_bus *bus)
INIT_LIST_HEAD(&dev->bus_list);
dev->dev.type = &pci_dev_type;
dev->bus = pci_bus_get(bus);
+ mutex_init(&dev->enable_mutex);
return dev;
}
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 77448215ef5b..cb2760a31fe2 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -419,6 +419,7 @@ struct pci_dev {
unsigned int no_vf_scan:1; /* Don't scan for VFs after IOV enablement */
pci_dev_flags_t dev_flags;
atomic_t enable_cnt; /* pci_enable_device has been called */
+ struct mutex enable_mutex;
u32 saved_config_space[16]; /* Config space saved at suspend time */
struct hlist_head saved_cap_space;
--
2.20.1
next prev parent reply other threads:[~2019-03-11 13:31 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-11 13:31 [PATCH RFC v4 00/21] PCI: Allow BAR movement during hotplug Sergey Miroshnichenko
2019-03-11 13:31 ` [PATCH RFC v4 01/21] PCI: Fix writing invalid BARs during pci_restore_state() Sergey Miroshnichenko
2019-03-26 14:02 ` Bjorn Helgaas
2019-03-11 13:31 ` Sergey Miroshnichenko [this message]
2019-03-26 19:00 ` [PATCH RFC v4 02/21] PCI: Fix race condition in pci_enable/disable_device() Bjorn Helgaas
2019-03-27 17:11 ` Sergey Miroshnichenko
2019-03-11 13:31 ` [PATCH RFC v4 03/21] PCI: Enable bridge's I/O and MEM access for hotplugged devices Sergey Miroshnichenko
2019-03-26 19:13 ` Bjorn Helgaas
2019-03-27 17:13 ` Sergey Miroshnichenko
2019-03-11 13:31 ` [PATCH RFC v4 04/21] PCI: Define PCI-specific version of the release_child_resources() Sergey Miroshnichenko
2019-03-11 13:31 ` [PATCH RFC v4 05/21] PCI: hotplug: Add a flag for the movable BARs feature Sergey Miroshnichenko
2019-03-26 19:24 ` Bjorn Helgaas
2019-03-27 17:16 ` Sergey Miroshnichenko
2019-03-11 13:31 ` [PATCH RFC v4 06/21] PCI: Pause the devices with movable BARs during rescan Sergey Miroshnichenko
2019-03-11 13:31 ` [PATCH RFC v4 07/21] PCI: Wake up bridges during rescan when movable BARs enabled Sergey Miroshnichenko
2019-03-26 19:28 ` Bjorn Helgaas
2019-03-11 13:31 ` [PATCH RFC v4 08/21] nvme-pci: Handle movable BARs Sergey Miroshnichenko
2019-03-26 20:20 ` Bjorn Helgaas
2019-03-27 17:30 ` Sergey Miroshnichenko
2019-03-11 13:31 ` [PATCH RFC v4 09/21] PCI: Mark immovable BARs with PCI_FIXED Sergey Miroshnichenko
2019-03-26 20:28 ` Bjorn Helgaas
2019-03-27 17:03 ` David Laight
2019-03-27 17:39 ` Sergey Miroshnichenko
2019-03-11 13:31 ` [PATCH RFC v4 10/21] PCI: Fix assigning of fixed prefetchable resources Sergey Miroshnichenko
2019-03-26 20:37 ` Bjorn Helgaas
2019-03-11 13:31 ` [PATCH RFC v4 11/21] PCI: Release and reassign the root bridge resources during rescan Sergey Miroshnichenko
2019-03-26 20:41 ` Bjorn Helgaas
2019-03-27 17:40 ` Sergey Miroshnichenko
2019-03-11 13:31 ` [PATCH RFC v4 12/21] PCI: Don't allow hotplugged devices to steal resources Sergey Miroshnichenko
2019-03-26 20:55 ` Bjorn Helgaas
2019-03-27 18:02 ` Sergey Miroshnichenko
2019-03-11 13:31 ` [PATCH RFC v4 13/21] PCI: Include fixed BARs into the bus size calculating Sergey Miroshnichenko
2019-03-11 13:31 ` [PATCH RFC v4 14/21] PCI: Don't reserve memory for hotplug when enabled movable BARs Sergey Miroshnichenko
2019-03-26 20:57 ` Bjorn Helgaas
2019-03-11 13:31 ` [PATCH RFC v4 15/21] PCI: Allow the failed resources to be reassigned later Sergey Miroshnichenko
2019-03-26 20:58 ` Bjorn Helgaas
2019-03-11 13:31 ` [PATCH RFC v4 16/21] PCI: Calculate fixed areas of bridge windows based on fixed BARs Sergey Miroshnichenko
2019-03-11 13:31 ` [PATCH RFC v4 17/21] PCI: Calculate boundaries for bridge windows Sergey Miroshnichenko
2019-03-26 21:01 ` Bjorn Helgaas
2019-03-11 13:31 ` [PATCH RFC v4 18/21] PCI: Make sure bridge windows include their fixed BARs Sergey Miroshnichenko
2019-03-11 13:31 ` [PATCH RFC v4 19/21] PCI: Prioritize fixed BAR assigning over the movable ones Sergey Miroshnichenko
2019-03-11 13:31 ` [PATCH RFC v4 20/21] PCI: pciehp: Add support for the movable BARs feature Sergey Miroshnichenko
2019-03-26 21:11 ` Bjorn Helgaas
2019-03-11 13:31 ` [PATCH RFC v4 21/21] powerpc/pci: Fix crash with enabled movable BARs Sergey Miroshnichenko
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