[<prev] [next>] [thread-next>] [day] [month] [year] [list]
Message-ID: <20231027152928.184012-1-marpagan@redhat.com>
Date: Fri, 27 Oct 2023 17:29:27 +0200
From: Marco Pagani <marpagan@...hat.com>
To: Moritz Fischer <mdf@...nel.org>, Wu Hao <hao.wu@...el.com>,
Xu Yilun <yilun.xu@...el.com>, Tom Rix <trix@...hat.com>,
Alan Tull <atull@...nsource.altera.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Marco Pagani <marpagan@...hat.com>, linux-fpga@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [RFC PATCH] fpga: remove module reference counting from core components
Remove unnecessary module reference counting from the core components
of the subsystem. Low-level driver modules cannot be removed before
core modules since they use their exported symbols.
For more context, refer to this thread:
https://lore.kernel.org/linux-fpga/ZS6hhlvjUcqyv8zL@yilunxu-OptiPlex-7050
Other changes:
In __fpga_bridge_get(): do a (missing ?) get_device() and bind the
image to the bridge only after the mutex has been acquired.
In __fpga_mgr_get(): do a get_device(). Currently, get_device() is
called when allocating an image in fpga_image_info_alloc().
However, since there are still two (of_)fpga_mgr_get() functions
exposed by the core, I think they should behave as expected.
In fpga_region_get() / fpga_region_put(): call get_device() before
acquiring the mutex and put_device() after having released the mutex
to avoid races.
Fixes: 654ba4cc0f3e ("fpga manager: ensure lifetime with of_fpga_mgr_get")
Signed-off-by: Marco Pagani <marpagan@...hat.com>
---
drivers/fpga/fpga-bridge.c | 24 +++++++-----------------
drivers/fpga/fpga-mgr.c | 8 +-------
drivers/fpga/fpga-region.c | 14 ++++----------
3 files changed, 12 insertions(+), 34 deletions(-)
diff --git a/drivers/fpga/fpga-bridge.c b/drivers/fpga/fpga-bridge.c
index a024be2b84e2..3bcc9c9849c5 100644
--- a/drivers/fpga/fpga-bridge.c
+++ b/drivers/fpga/fpga-bridge.c
@@ -58,30 +58,21 @@ EXPORT_SYMBOL_GPL(fpga_bridge_disable);
static struct fpga_bridge *__fpga_bridge_get(struct device *dev,
struct fpga_image_info *info)
{
- struct fpga_bridge *bridge;
- int ret = -ENODEV;
-
- bridge = to_fpga_bridge(dev);
+ struct fpga_bridge *bridge = to_fpga_bridge(dev);
- bridge->info = info;
+ get_device(dev);
if (!mutex_trylock(&bridge->mutex)) {
- ret = -EBUSY;
- goto err_dev;
+ dev_dbg(dev, "%s: FPGA Bridge already in use\n", __func__);
+ put_device(dev);
+ return ERR_PTR(-EBUSY);
}
- if (!try_module_get(dev->parent->driver->owner))
- goto err_ll_mod;
+ bridge->info = info;
dev_dbg(&bridge->dev, "get\n");
return bridge;
-
-err_ll_mod:
- mutex_unlock(&bridge->mutex);
-err_dev:
- put_device(dev);
- return ERR_PTR(ret);
}
/**
@@ -93,7 +84,7 @@ static struct fpga_bridge *__fpga_bridge_get(struct device *dev,
* Return:
* * fpga_bridge struct pointer if successful.
* * -EBUSY if someone already has a reference to the bridge.
- * * -ENODEV if @np is not an FPGA Bridge or can't take parent driver refcount.
+ * * -ENODEV if @np is not an FPGA Bridge.
*/
struct fpga_bridge *of_fpga_bridge_get(struct device_node *np,
struct fpga_image_info *info)
@@ -146,7 +137,6 @@ void fpga_bridge_put(struct fpga_bridge *bridge)
dev_dbg(&bridge->dev, "put\n");
bridge->info = NULL;
- module_put(bridge->dev.parent->driver->owner);
mutex_unlock(&bridge->mutex);
put_device(&bridge->dev);
}
diff --git a/drivers/fpga/fpga-mgr.c b/drivers/fpga/fpga-mgr.c
index 06651389c592..6c355eafd18f 100644
--- a/drivers/fpga/fpga-mgr.c
+++ b/drivers/fpga/fpga-mgr.c
@@ -670,14 +670,9 @@ static struct fpga_manager *__fpga_mgr_get(struct device *dev)
mgr = to_fpga_manager(dev);
- if (!try_module_get(dev->parent->driver->owner))
- goto err_dev;
+ get_device(&mgr->dev);
return mgr;
-
-err_dev:
- put_device(dev);
- return ERR_PTR(-ENODEV);
}
static int fpga_mgr_dev_match(struct device *dev, const void *data)
@@ -727,7 +722,6 @@ EXPORT_SYMBOL_GPL(of_fpga_mgr_get);
*/
void fpga_mgr_put(struct fpga_manager *mgr)
{
- module_put(mgr->dev.parent->driver->owner);
put_device(&mgr->dev);
}
EXPORT_SYMBOL_GPL(fpga_mgr_put);
diff --git a/drivers/fpga/fpga-region.c b/drivers/fpga/fpga-region.c
index b364a929425c..c299956cafdc 100644
--- a/drivers/fpga/fpga-region.c
+++ b/drivers/fpga/fpga-region.c
@@ -41,22 +41,17 @@ EXPORT_SYMBOL_GPL(fpga_region_class_find);
* Return:
* * fpga_region struct if successful.
* * -EBUSY if someone already has a reference to the region.
- * * -ENODEV if can't take parent driver module refcount.
*/
static struct fpga_region *fpga_region_get(struct fpga_region *region)
{
struct device *dev = ®ion->dev;
+ get_device(dev);
+
if (!mutex_trylock(®ion->mutex)) {
dev_dbg(dev, "%s: FPGA Region already in use\n", __func__);
- return ERR_PTR(-EBUSY);
- }
-
- get_device(dev);
- if (!try_module_get(dev->parent->driver->owner)) {
put_device(dev);
- mutex_unlock(®ion->mutex);
- return ERR_PTR(-ENODEV);
+ return ERR_PTR(-EBUSY);
}
dev_dbg(dev, "get\n");
@@ -75,9 +70,8 @@ static void fpga_region_put(struct fpga_region *region)
dev_dbg(dev, "put\n");
- module_put(dev->parent->driver->owner);
- put_device(dev);
mutex_unlock(®ion->mutex);
+ put_device(dev);
}
/**
--
2.41.0
Powered by blists - more mailing lists