[cip-dev] [RFC PATCH 4.19.y-cip 25/50] PCI: endpoint: Protect concurrent access to pci_epf_ops with mutex

Lad Prabhakar
2020-10-12T14:20:47Z

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From: Kishon Vijay Abraham I <kishon@ti.com>

commit 07301c982643a432212840a4b648b5d3f5a061fa upstream.

Protect concurrent access to pci_epf_ops with a mutex.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
---
drivers/pci/endpoint/pci-epf-core.c | 11 ++++++++++-
include/linux/pci-epf.h | 3 +++
2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/endpoint/pci-epf-core.c b/drivers/pci/endpoint/pci-epf-core.c
index 93f28c65ace0..6e0648991b5c 100644
--- a/drivers/pci/endpoint/pci-epf-core.c
+++ b/drivers/pci/endpoint/pci-epf-core.c
@@ -35,7 +35,9 @@ void pci_epf_unbind(struct pci_epf *epf)
return;
}

+ mutex_lock(&epf->lock);
epf->driver->ops->unbind(epf);
+ mutex_unlock(&epf->lock);
module_put(epf->driver->owner);
}
EXPORT_SYMBOL_GPL(pci_epf_unbind);
@@ -49,6 +51,8 @@ EXPORT_SYMBOL_GPL(pci_epf_unbind);
*/
int pci_epf_bind(struct pci_epf *epf)
{
+ int ret;
+
if (!epf->driver) {
dev_WARN(&epf->dev, "epf device not bound to driver\n");
return -EINVAL;
@@ -57,7 +61,11 @@ int pci_epf_bind(struct pci_epf *epf)
if (!try_module_get(epf->driver->owner))
return -EAGAIN;

- return epf->driver->ops->bind(epf);
+ mutex_lock(&epf->lock);
+ ret = epf->driver->ops->bind(epf);
+ mutex_unlock(&epf->lock);
+
+ return ret;
}
EXPORT_SYMBOL_GPL(pci_epf_bind);

@@ -252,6 +260,7 @@ struct pci_epf *pci_epf_create(const char *name)
device_initialize(dev);
dev->bus = &pci_epf_bus_type;
dev->type = &pci_epf_type;
+ mutex_init(&epf->lock);

ret = dev_set_name(dev, "%s", name);
if (ret) {
diff --git a/include/linux/pci-epf.h b/include/linux/pci-epf.h
index 4993f7f6439b..bcdf4f07bde7 100644
--- a/include/linux/pci-epf.h
+++ b/include/linux/pci-epf.h
@@ -110,6 +110,7 @@ struct pci_epf_bar {
* @driver: the EPF driver to which this EPF device is bound
* @list: to add pci_epf as a list of PCI endpoint functions to pci_epc
* @nb: notifier block to notify EPF of any EPC events (like linkup)
+ * @lock: mutex to protect pci_epf_ops
*/
struct pci_epf {
struct device dev;
@@ -124,6 +125,8 @@ struct pci_epf {
struct pci_epf_driver *driver;
struct list_head list;
struct notifier_block nb;
+ /* mutex to protect against concurrent access of pci_epf_ops */
+ struct mutex lock;
};

#define to_pci_epf(epf_dev) container_of((epf_dev), struct pci_epf, dev)
--
2.17.1

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