From: Sergey Miroshnichenko <s.miroshnichenko@yadro.com>
To: <linux-pci@vger.kernel.org>
Cc: <linux@yadro.com>, Sergey Miroshnichenko <s.miroshnichenko@yadro.com>
Subject: [PATCH RFC v2 15/21] PCI: Fix race condition in pci_enable/disable_device()
Date: Fri, 11 Jan 2019 18:37:01 +0300 [thread overview]
Message-ID: <20190111153707.10140-16-s.miroshnichenko@yadro.com> (raw)
In-Reply-To: <20190111153707.10140-1-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 71e056771e67..a5266f31b612 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1595,6 +1595,8 @@ 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);
@@ -1602,6 +1604,7 @@ 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;
}
@@ -1610,11 +1613,14 @@ 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;
@@ -1630,8 +1636,13 @@ 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)
@@ -1646,8 +1657,10 @@ 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;
}
@@ -1890,15 +1903,20 @@ 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 34c769b25055..4726049a19ad 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -2197,6 +2197,7 @@ 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 161a9b8a854e..311d51d0a59a 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -417,6 +417,7 @@ 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:[~2019-01-11 15:43 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-11 15:36 [PATCH RFC v2 00/21] PCI: Allow BAR movement during hotplug Sergey Miroshnichenko
2019-01-11 15:36 ` [PATCH RFC v2 01/21] PCI: Fix writing invalid BARs during pci_restore_state() Sergey Miroshnichenko
2019-01-11 15:36 ` [PATCH RFC v2 02/21] PCI: Define PCI-specific version of the release_child_resources() Sergey Miroshnichenko
2019-01-11 15:36 ` [PATCH RFC v2 03/21] PCI: hotplug: Add a flag for the movable BARs feature Sergey Miroshnichenko
2019-01-11 15:36 ` [PATCH RFC v2 04/21] PCI: Pause the devices with movable BARs during rescan Sergey Miroshnichenko
2019-01-11 15:36 ` [PATCH RFC v2 05/21] PCI: Release and reassign the root bridge resources " Sergey Miroshnichenko
2019-01-11 15:36 ` [PATCH RFC v2 06/21] PCI: Don't allow hotplugged devices to steal resources Sergey Miroshnichenko
2019-01-11 15:36 ` [PATCH RFC v2 07/21] PCI: Mark immovable BARs with PCI_FIXED Sergey Miroshnichenko
2019-01-11 15:36 ` [PATCH RFC v2 08/21] PCI: Include fixed BARs into the bus size calculating Sergey Miroshnichenko
2019-01-11 15:36 ` [PATCH RFC v2 09/21] PCI: Don't reserve memory for hotplug when enabled movable BARs Sergey Miroshnichenko
2019-01-11 15:36 ` [PATCH RFC v2 10/21] PCI: Allow the failed resources to be reassigned later Sergey Miroshnichenko
2019-01-11 15:36 ` [PATCH RFC v2 11/21] PCI: Calculate fixed areas of bridge windows based on fixed BARs Sergey Miroshnichenko
2019-01-11 15:36 ` [PATCH RFC v2 12/21] PCI: Calculate boundaries for bridge windows Sergey Miroshnichenko
2019-01-11 15:36 ` [PATCH RFC v2 13/21] PCI: Make sure bridge windows include their fixed BARs Sergey Miroshnichenko
2019-01-11 15:37 ` [PATCH RFC v2 14/21] PCI: Prioritize fixed BAR assigning over the movable ones Sergey Miroshnichenko
2019-01-11 15:37 ` Sergey Miroshnichenko [this message]
2019-01-11 15:37 ` [PATCH RFC v2 16/21] PCI: Enable bridge's I/O and MEM access for hotplugged devices Sergey Miroshnichenko
2019-01-11 15:37 ` [PATCH RFC v2 17/21] PCI: pciehp: Add support for the movable BARs feature Sergey Miroshnichenko
2019-01-11 15:37 ` [PATCH RFC v2 18/21] nvme-pci: Handle movable BARs Sergey Miroshnichenko
2019-01-11 15:37 ` [PATCH RFC v2 19/21] powerpc/pci: Fix crash with enabled " Sergey Miroshnichenko
2019-01-11 15:37 ` [PATCH RFC v2 20/21] PCI: Wake up bridges during rescan when movable BARs enabled Sergey Miroshnichenko
2019-01-11 15:37 ` [PATCH RFC v2 21/21] x86: enable movable BARs Sergey Miroshnichenko
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