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>,
Srinath Mannam <srinath.mannam@broadcom.com>,
Marta Rybczynska <mrybczyn@kalray.eu>
Subject: [PATCH v5 01/23] PCI: Fix race condition in pci_enable/disable_device()
Date: Fri, 16 Aug 2019 19:50:39 +0300 [thread overview]
Message-ID: <20190816165101.911-2-s.miroshnichenko@yadro.com> (raw)
In-Reply-To: <20190816165101.911-1-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;
- during boot, if BIOS/bootloader/firmware doesn't pre-enable bridges.
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/disable_device() and pci_enable_bridge(), which is
similar to the previous solution from commit 40f11adc7cd9 ("PCI: Avoid race
while enabling upstream bridges"), but adding a per-device mutexes and
preventing the dev->enable_cnt from from incrementing early.
CC: Srinath Mannam <srinath.mannam@broadcom.com>
CC: Marta Rybczynska <mrybczyn@kalray.eu>
Signed-off-by: Sergey 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 | 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 1b27b5af3d55..e7f8c354e644 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1645,6 +1645,8 @@ 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);
@@ -1652,6 +1654,7 @@ 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;
}
@@ -1660,11 +1663,14 @@ 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;
@@ -1680,8 +1686,13 @@ 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)
@@ -1696,8 +1707,10 @@ 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;
}
@@ -1941,15 +1954,20 @@ 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 a3c7338fad86..2e58ece820e8 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -2427,6 +2427,7 @@ 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 9e700d9f9f28..d3a72159722d 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -425,6 +425,7 @@ 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;
--
2.21.0
next prev parent reply other threads:[~2019-08-16 16:51 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-16 16:50 [PATCH v5 00/23] PCI: Allow BAR movement during hotplug Sergey Miroshnichenko
2019-08-16 16:50 ` Sergey Miroshnichenko [this message]
2019-08-22 12:37 ` [PATCH v5 01/23] PCI: Fix race condition in pci_enable/disable_device() Marta Rybczynska
2019-09-27 21:59 ` Bjorn Helgaas
2019-09-30 8:53 ` Sergey Miroshnichenko
2019-08-16 16:50 ` [PATCH v5 02/23] PCI: Enable bridge's I/O and MEM access for hotplugged devices Sergey Miroshnichenko
2019-09-27 22:01 ` Bjorn Helgaas
2019-08-16 16:50 ` [PATCH v5 03/23] PCI: hotplug: Add a flag for the movable BARs feature Sergey Miroshnichenko
2019-09-27 22:02 ` Bjorn Helgaas
2019-09-30 8:44 ` David Laight
2019-09-30 16:17 ` Sergey Miroshnichenko
2019-09-30 12:59 ` Sergey Miroshnichenko
2019-10-15 22:14 ` Bjorn Helgaas
2019-10-16 15:50 ` Sergey Miroshnichenko
2019-10-16 17:29 ` Bjorn Helgaas
2019-08-16 16:50 ` [PATCH v5 04/23] PCI: Define PCI-specific version of the release_child_resources() Sergey Miroshnichenko
2019-08-16 16:50 ` [PATCH v5 05/23] PCI: hotplug: movable BARs: Fix reassigning the released bridge windows Sergey Miroshnichenko
2019-08-16 16:50 ` [PATCH v5 06/23] PCI: hotplug: movable BARs: Recalculate all bridge windows during rescan Sergey Miroshnichenko
2019-08-16 16:50 ` [PATCH v5 07/23] PCI: hotplug: movable BARs: Don't allow added devices to steal resources Sergey Miroshnichenko
2019-08-16 16:50 ` [PATCH v5 08/23] PCI: Include fixed and immovable BARs into the bus size calculating Sergey Miroshnichenko
2019-08-16 16:50 ` [PATCH v5 09/23] PCI: Prohibit assigning BARs and bridge windows to non-direct parents Sergey Miroshnichenko
2019-08-16 16:50 ` [PATCH v5 10/23] PCI: hotplug: movable BARs: Try to assign unassigned resources only once Sergey Miroshnichenko
2019-08-16 16:50 ` [PATCH v5 11/23] PCI: hotplug: movable BARs: Calculate immovable parts of bridge windows Sergey Miroshnichenko
2019-08-16 16:50 ` [PATCH v5 12/23] PCI: hotplug: movable BARs: Compute limits for relocated " Sergey Miroshnichenko
2019-08-16 16:50 ` [PATCH v5 13/23] PCI: Make sure bridge windows include their fixed BARs Sergey Miroshnichenko
2019-08-16 16:50 ` [PATCH v5 14/23] PCI: Fix assigning the fixed prefetchable resources Sergey Miroshnichenko
2019-08-16 16:50 ` [PATCH v5 15/23] PCI: hotplug: movable BARs: Assign fixed and immovable BARs before others Sergey Miroshnichenko
2019-08-16 16:50 ` [PATCH v5 16/23] PCI: hotplug: movable BARs: Don't reserve IO/mem bus space Sergey Miroshnichenko
2019-09-04 5:42 ` Oliver O'Halloran
2019-09-04 11:22 ` Sergey Miroshnichenko
2019-08-16 16:50 ` [PATCH v5 17/23] powerpc/pci: Fix crash with enabled movable BARs Sergey Miroshnichenko
2019-08-16 16:50 ` [PATCH v5 18/23] powerpc/pci: Handle BAR movement Sergey Miroshnichenko
2019-09-04 5:37 ` Oliver O'Halloran
2019-09-06 16:24 ` Sergey Miroshnichenko
2019-09-09 14:02 ` Oliver O'Halloran
2019-08-16 16:50 ` [PATCH v5 19/23] PCI: hotplug: Configure MPS for hot-added bridges during bus rescan Sergey Miroshnichenko
2019-08-16 16:50 ` [PATCH v5 20/23] PCI: hotplug: movable BARs: Enable the feature by default Sergey Miroshnichenko
2019-08-16 16:50 ` [PATCH v5 21/23] nvme-pci: Handle movable BARs Sergey Miroshnichenko
2019-08-16 16:51 ` [PATCH v5 22/23] PCI/portdrv: Declare support of " Sergey Miroshnichenko
2019-08-16 16:51 ` [PATCH v5 23/23] PCI: pciehp: movable BARs: Trigger a domain rescan on hp events Sergey Miroshnichenko
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190816165101.911-2-s.miroshnichenko@yadro.com \
--to=s.miroshnichenko@yadro.com \
--cc=helgaas@kernel.org \
--cc=linux-pci@vger.kernel.org \
--cc=linux@yadro.com \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=mrybczyn@kalray.eu \
--cc=srinath.mannam@broadcom.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).