From: Sergei Miroshnichenko <s.miroshnichenko@yadro.com>
To: <linux-pci@vger.kernel.org>
Cc: "Bjorn Helgaas" <helgaas@kernel.org>,
"Lukas Wunner" <lukas@wunner.de>, "Stefan Roese" <sr@denx.de>,
"Andy Lavr" <andy.lavr@gmail.com>,
"Christian König" <christian.koenig@amd.com>,
"David Laight" <David.Laight@ACULAB.COM>,
"Rajat Jain" <rajatja@google.com>,
linux@yadro.com,
"Sergei Miroshnichenko" <s.miroshnichenko@yadro.com>,
"Srinath Mannam" <srinath.mannam@broadcom.com>,
"Marta Rybczynska" <mrybczyn@kalray.eu>
Subject: [PATCH v9 01/26] PCI: Fix race condition in pci_enable/disable_device()
Date: Fri, 18 Dec 2020 20:39:46 +0300 [thread overview]
Message-ID: <20201218174011.340514-2-s.miroshnichenko@yadro.com> (raw)
In-Reply-To: <20201218174011.340514-1-s.miroshnichenko@yadro.com>
This is a yet another approach to fix an old [1-2] concurrency issue, when:
- two or more devices are being hot-added into a bridge which was
initially empty;
- a bridge with two or more devices is being hot-added;
- the BIOS/bootloader/firmware doesn't pre-enable bridges during boot;
The problem is that a bridge is reported as enabled before the MEM/IO bits
are actually written to the PCI_COMMAND register, so another driver thread
starts memory requests through the not-yet-enabled bridge:
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
Protect the pci_enable_bridge(), similarly to the previous solution from
commit 40f11adc7cd9 ("PCI: Avoid race while enabling upstream bridges"),
but adding per-device mutexes.
To prevent false positives from the lockdep, use a lock_nested() with a
"depth" of a bridge within the PCI topology.
CC: Srinath Mannam <srinath.mannam@broadcom.com>
CC: Marta Rybczynska <mrybczyn@kalray.eu>
Signed-off-by: Sergei Miroshnichenko <s.miroshnichenko@yadro.com>
[1] https://lore.kernel.org/linux-pci/1501858648-22228-1-git-send-email-srinath.mannam@broadcom.com/T/#u
[RFC PATCH v3] pci: Concurrency issue during pci enable bridge
[2] https://lore.kernel.org/linux-pci/744877924.5841545.1521630049567.JavaMail.zimbra@kalray.eu/T/#u
[RFC PATCH] nvme: avoid race-conditions when enabling devices
---
drivers/pci/pci.c | 16 ++++++++++++++++
drivers/pci/probe.c | 1 +
include/linux/pci.h | 1 +
3 files changed, 18 insertions(+)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index b9fecc25d213..076b908127fe 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1844,11 +1844,25 @@ int pci_reenable_device(struct pci_dev *dev)
}
EXPORT_SYMBOL(pci_reenable_device);
+#ifdef CONFIG_PROVE_LOCKING
+static int pci_bridge_depth(struct pci_dev *dev)
+{
+ struct pci_dev *bridge = pci_upstream_bridge(dev);
+
+ if (!bridge)
+ return 0;
+
+ return 1 + pci_bridge_depth(bridge);
+}
+#endif /* CONFIG_PROVE_LOCKING */
+
static void pci_enable_bridge(struct pci_dev *dev)
{
struct pci_dev *bridge;
int retval;
+ mutex_lock_nested(&dev->enable_mutex, pci_bridge_depth(dev));
+
bridge = pci_upstream_bridge(dev);
if (bridge)
pci_enable_bridge(bridge);
@@ -1856,6 +1870,7 @@ 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;
}
@@ -1864,6 +1879,7 @@ 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)
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 953f15abc850..2f9631287719 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -2240,6 +2240,7 @@ 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 b32126d26997..81d54889bd51 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -455,6 +455,7 @@ struct pci_dev {
unsigned int no_command_memory:1; /* No PCI_COMMAND_MEMORY */
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;
--
2.24.1
next prev parent reply other threads:[~2020-12-18 17:42 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-18 17:39 [PATCH v9 00/26] PCI: Allow BAR movement during boot and hotplug Sergei Miroshnichenko
2020-12-18 17:39 ` Sergei Miroshnichenko [this message]
2020-12-28 15:37 ` [PATCH v9 01/26] PCI: Fix race condition in pci_enable/disable_device() Sergei Miroshnichenko
2020-12-18 17:39 ` [PATCH v9 02/26] PCI: Ensure a bridge has I/O and MEM access for hot-added devices Sergei Miroshnichenko
2020-12-18 17:39 ` [PATCH v9 03/26] PCI: hotplug: Initial support of the movable BARs feature Sergei Miroshnichenko
2020-12-18 17:39 ` [PATCH v9 04/26] PCI: Add version of release_child_resources() aware of fixed BARs Sergei Miroshnichenko
2020-12-18 17:39 ` [PATCH v9 05/26] PCI: hotplug: Fix reassigning the released BARs Sergei Miroshnichenko
2020-12-18 17:39 ` [PATCH v9 06/26] PCI: hotplug: Recalculate every bridge window during rescan Sergei Miroshnichenko
2020-12-18 17:39 ` [PATCH v9 07/26] PCI: hotplug: Don't allow hot-added devices to steal resources Sergei Miroshnichenko
2020-12-18 17:39 ` [PATCH v9 08/26] PCI: Reassign BARs if BIOS/bootloader had assigned not all of them Sergei Miroshnichenko
2020-12-18 17:39 ` [PATCH v9 09/26] PCI: Movable BARs: Make just a single attempt to assign bridge resources Sergei Miroshnichenko
2020-12-18 17:39 ` [PATCH v9 10/26] PCI: hotplug: Calculate fixed parts of bridge windows Sergei Miroshnichenko
2020-12-18 17:39 ` [PATCH v9 11/26] PCI: Include fixed BARs into the bus size calculating Sergei Miroshnichenko
2020-12-18 17:39 ` [PATCH v9 12/26] PCI: Make sure bridge windows include their fixed BARs Sergei Miroshnichenko
2020-12-18 17:39 ` [PATCH v9 13/26] PCI: hotplug: Add support of fixed BARs to pci_assign_resource() Sergei Miroshnichenko
2020-12-18 17:39 ` [PATCH v9 14/26] PCI: hotplug: Sort fixed BARs before assignment Sergei Miroshnichenko
2020-12-18 17:40 ` [PATCH v9 15/26] x86/PCI/ACPI: Fix up PCIBIOS_MIN_MEM if value computed from e820 is invalid Sergei Miroshnichenko
2020-12-18 17:40 ` [PATCH v9 16/26] PCI: hotplug: Configure MPS after manual bus rescan Sergei Miroshnichenko
2020-12-18 17:40 ` [PATCH v9 17/26] PCI: hotplug: Don't disable the released bridge windows immediately Sergei Miroshnichenko
2020-12-18 17:40 ` [PATCH v9 18/26] PCI: pciehp: Trigger a domain rescan on hp events when enabled movable BARs Sergei Miroshnichenko
2020-12-18 17:40 ` [PATCH v9 19/26] PCI: Don't claim fixed BARs Sergei Miroshnichenko
2020-12-18 17:40 ` [PATCH v9 20/26] PCI: hotplug: Retry bus assignment without reserved space Sergei Miroshnichenko
2020-12-18 17:40 ` [PATCH v9 21/26] PCI: Rescan the bus to resize a BAR Sergei Miroshnichenko
2020-12-18 17:40 ` [PATCH v9 22/26] PCI: hotplug: Enable the movable BARs feature by default Sergei Miroshnichenko
2020-12-18 17:40 ` [PATCH v9 23/26] PCI/portdrv: Declare support of movable BARs Sergei Miroshnichenko
2020-12-18 17:40 ` [PATCH v9 24/26] nvme-pci: Handle " Sergei Miroshnichenko
2020-12-18 17:40 ` [PATCH v9 25/26] PCI: Add a message for updating BARs Sergei Miroshnichenko
2020-12-18 17:40 ` [PATCH v9 26/26] resource: increase max nesting level for /proc/iomem Sergei Miroshnichenko
2021-01-28 14:53 ` [PATCH v9 00/26] PCI: Allow BAR movement during boot and hotplug Bjorn Helgaas
2021-01-28 20:39 ` Lukas Wunner
2021-02-01 12:55 ` Mika Westerberg
2021-02-03 20:17 ` Sergei Miroshnichenko
2021-02-04 10:49 ` mika.westerberg
2021-02-10 19:40 ` Sergei Miroshnichenko
2021-02-10 21:46 ` Lukas Wunner
2021-02-11 11:39 ` mika.westerberg
2021-02-11 17:45 ` Sergei Miroshnichenko
2021-02-12 12:52 ` mika.westerberg
2021-02-12 20:54 ` Sergei Miroshnichenko
2021-02-15 14:56 ` mika.westerberg
2021-02-03 20:01 ` Sergei Miroshnichenko
2021-02-04 9:34 ` David Laight
2021-02-03 19:59 ` Sergei Miroshnichenko
2021-02-04 8:26 ` Hinko Kocevar
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