[PATCH v5 2/5] cdx: Introduce lock to protect controller ops

From: Abhijit Gangurde
Date: Fri Sep 22 2023 - 06:19:51 EST


Add a mutex lock to prevent race between controller ops initiated by
the bus subsystem and the controller registration/unregistration.

Signed-off-by: Abhijit Gangurde <abhijit.gangurde@xxxxxxx>
---
Changes in v5:
- None

Changes in v4:
- None

Changes in v3:
- None

Changes in v2:
- New patch in the series
- Introduce new lock

drivers/cdx/cdx.c | 12 ++++++++++++
1 file changed, 12 insertions(+)

diff --git a/drivers/cdx/cdx.c b/drivers/cdx/cdx.c
index 600482694161..cbfe9a2f3646 100644
--- a/drivers/cdx/cdx.c
+++ b/drivers/cdx/cdx.c
@@ -72,6 +72,8 @@

/* IDA for CDX controllers registered with the CDX bus */
static DEFINE_IDA(cdx_controller_ida);
+/* Lock to protect controller ops */
+static DEFINE_MUTEX(cdx_controller_lock);

static char *compat_node_name = "xlnx,versal-net-cdx";

@@ -396,6 +398,8 @@ static ssize_t rescan_store(const struct bus_type *bus,
if (!val)
return -EINVAL;

+ mutex_lock(&cdx_controller_lock);
+
/* Unregister all the devices on the bus */
cdx_unregister_devices(&cdx_bus_type);

@@ -415,6 +419,8 @@ static ssize_t rescan_store(const struct bus_type *bus,
put_device(&pd->dev);
}

+ mutex_unlock(&cdx_controller_lock);
+
return count;
}
static BUS_ATTR_WO(rescan);
@@ -538,11 +544,13 @@ int cdx_register_controller(struct cdx_controller *cdx)
return ret;
}

+ mutex_lock(&cdx_controller_lock);
cdx->id = ret;

/* Scan all the devices */
cdx->ops->scan(cdx);
cdx->controller_registered = true;
+ mutex_unlock(&cdx_controller_lock);

return 0;
}
@@ -553,9 +561,13 @@ void cdx_unregister_controller(struct cdx_controller *cdx)
if (cdx->id >= MAX_CDX_CONTROLLERS)
return;

+ mutex_lock(&cdx_controller_lock);
+
cdx->controller_registered = false;
device_for_each_child(cdx->dev, NULL, cdx_unregister_device);
ida_free(&cdx_controller_ida, cdx->id);
+
+ mutex_unlock(&cdx_controller_lock);
}
EXPORT_SYMBOL_GPL(cdx_unregister_controller);

--
2.25.1