From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Bjorn Helgaas <helgaas@kernel.org>, linux-pci@vger.kernel.org
Cc: Hari Vyas <hari.vyas@broadcom.com>,
Ray Jui <ray.jui@broadcom.com>,
Srinath Mannam <srinath.mannam@broadcom.com>,
Guenter Roeck <linux@roeck-us.net>, Jens Axboe <axboe@kernel.dk>,
Lukas Wunner <lukas@wunner.de>,
Konstantin Khlebnikov <khlebnikov@yandex-team.ru>,
Marta Rybczynska <mrybczyn@kalray.eu>,
Pierre-Yves Kerbrat <pkerbrat@kalray.eu>,
linux-kernel@vger.kernel.org,
Benjamin Herrenschmidt <benh@kernel.crashing.org>
Subject: [RFC PATCH 6/6] pci: Protect is_busmaster using the state lock
Date: Fri, 17 Aug 2018 14:49:02 +1000 [thread overview]
Message-ID: <20180817044902.31420-7-benh@kernel.crashing.org> (raw)
In-Reply-To: <20180817044902.31420-1-benh@kernel.crashing.org>
This wraps pci_set_master() and pci_clear_master() with the pci_dev
state lock. The clearing of is_busmaster in pci_disable_device()
is already covered.
This also adds a comment explaining why is_busmaster must not be
checked in pci_set_master() due to how the power management code
uses it.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
drivers/pci/pci.c | 9 +++++++++
include/linux/pci.h | 2 +-
2 files changed, 10 insertions(+), 1 deletion(-)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 68152de2b5a0..13d988d5b2a3 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -4052,11 +4052,18 @@ void __weak pcibios_set_master(struct pci_dev *dev)
*
* Enables bus-mastering on the device and calls pcibios_set_master()
* to do the needed arch specific settings.
+ *
+ * Note: This must not check dev->is_busmaster because the power management
+ * code will call this in order to restore the config space to the
+ * state of is_busmaster, thus is_busmaster might be set but the
+ * config space bit cleared.
*/
void pci_set_master(struct pci_dev *dev)
{
+ pci_dev_state_lock(dev);
__pci_set_master(dev, true);
pcibios_set_master(dev);
+ pci_dev_state_unlock(dev);
}
EXPORT_SYMBOL(pci_set_master);
@@ -4066,7 +4073,9 @@ EXPORT_SYMBOL(pci_set_master);
*/
void pci_clear_master(struct pci_dev *dev)
{
+ pci_dev_state_lock(dev);
__pci_set_master(dev, false);
+ pci_dev_state_unlock(dev);
}
EXPORT_SYMBOL(pci_clear_master);
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 0d4fc22df190..a5bac5b21454 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -375,7 +375,6 @@ struct pci_dev {
unsigned int multifunction:1; /* Multi-function device */
unsigned int is_added:1;
- unsigned int is_busmaster:1; /* Is busmaster */
unsigned int no_msi:1; /* May not use MSI */
unsigned int no_64bit_msi:1; /* May only use 32-bit MSIs */
unsigned int block_cfg_access:1; /* Config space access blocked */
@@ -450,6 +449,7 @@ struct pci_dev {
struct mutex state_lock; /* Protect local state bits */
/* --- Fields below this line are protected by the state_lock mutex */
+ unsigned int is_busmaster:1; /* Is busmaster */
};
static inline void pci_dev_state_lock(struct pci_dev *dev)
--
2.17.1
next prev parent reply other threads:[~2018-08-17 5:24 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-17 4:48 [RFC PATCH 0/6] pci: Rework is_added race fix and address bridge enable races Benjamin Herrenschmidt
2018-08-17 4:48 ` [RFC PATCH 1/6] Revert "PCI: Fix is_added/is_busmaster race condition" Benjamin Herrenschmidt
2018-08-17 4:57 ` Benjamin Herrenschmidt
2018-08-17 15:44 ` Bjorn Helgaas
2018-08-18 3:24 ` Benjamin Herrenschmidt
2018-08-19 2:24 ` Bjorn Helgaas
2018-08-20 2:10 ` Benjamin Herrenschmidt
2018-08-20 6:25 ` Hari Vyas
2018-08-20 11:09 ` Benjamin Herrenschmidt
2018-08-20 11:43 ` Hari Vyas
2018-08-20 7:17 ` Lukas Wunner
2018-08-20 11:12 ` Benjamin Herrenschmidt
2018-08-17 4:48 ` [RFC PATCH 2/6] pci: Set pci_dev->is_added before calling device_add Benjamin Herrenschmidt
2018-08-17 4:57 ` Benjamin Herrenschmidt
2018-08-17 16:25 ` Bjorn Helgaas
2018-08-17 18:15 ` Lukas Wunner
2018-08-18 3:41 ` Benjamin Herrenschmidt
2018-08-18 3:28 ` Benjamin Herrenschmidt
2018-08-17 4:48 ` [RFC PATCH 3/6] pci: Remove priv_flags and use dev->error_state for "disconnected" status Benjamin Herrenschmidt
2018-08-17 5:13 ` [RFC PATCH v2 " Benjamin Herrenschmidt
2018-08-17 4:49 ` [RFC PATCH 4/6] pci: Add a mutex to pci_dev to protect device state Benjamin Herrenschmidt
2018-08-17 4:49 ` [RFC PATCH 5/6] pci: Protect the enable/disable state of pci_dev using the state mutex Benjamin Herrenschmidt
2018-08-17 8:09 ` Marta Rybczynska
2018-08-17 8:30 ` Benjamin Herrenschmidt
2018-08-17 9:00 ` Hari Vyas
2018-08-17 9:39 ` Benjamin Herrenschmidt
2018-08-17 10:10 ` Hari Vyas
2018-08-17 10:24 ` Benjamin Herrenschmidt
2018-08-17 4:49 ` Benjamin Herrenschmidt [this message]
2018-08-17 5:03 ` [RFC PATCH 0/6] pci: Rework is_added race fix and address bridge enable races Benjamin Herrenschmidt
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