[PATCH v6 03/10] PCI: Warn users about complicated devres nature

Philipp Stanner
2024-04-08T08:44:38Z

The PCI region-request functions become managed functions when
pcim_enable_device() has been called previously instead of
pci_enable_device().

This has already caused bugs by confusing users, who came to believe
that all pci functions, such as pci_iomap_range(), suddenly are managed
that way.

This is not the case.

Add comments to the relevant functions' docstrings that warn users about
this behavior.

Signed-off-by: Philipp Stanner <pstanner@redhat.com>
---
drivers/pci/iomap.c | 18 ++++++++++++++
drivers/pci/pci.c | 60 ++++++++++++++++++++++++++++++++++++++++++++-
2 files changed, 77 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/iomap.c b/drivers/pci/iomap.c
index c9725428e387..ea3b9842132a 100644
--- a/drivers/pci/iomap.c
+++ b/drivers/pci/iomap.c
@@ -23,6 +23,11 @@
*
* @maxlen specifies the maximum length to map. If you want to get access to
* the complete BAR from offset to the end, pass %0 here.
+ *
+ * NOTE:
+ * This function is never managed, even if you initialized with
+ * pcim_enable_device().
+ * If you need automatic cleanup, use pcim_iomap_range().
* */
void __iomem *pci_iomap_range(struct pci_dev *dev,
int bar,
@@ -63,6 +68,10 @@ EXPORT_SYMBOL(pci_iomap_range);
*
* @maxlen specifies the maximum length to map. If you want to get access to
* the complete BAR from offset to the end, pass %0 here.
+ *
+ * NOTE:
+ * This function is never managed, even if you initialized with
+ * pcim_enable_device().
* */
void __iomem *pci_iomap_wc_range(struct pci_dev *dev,
int bar,
@@ -106,6 +115,11 @@ EXPORT_SYMBOL_GPL(pci_iomap_wc_range);
*
* @maxlen specifies the maximum length to map. If you want to get access to
* the complete BAR without checking for its length first, pass %0 here.
+ *
+ * NOTE:
+ * This function is never managed, even if you initialized with
+ * pcim_enable_device().
+ * If you need automatic cleanup, use pcim_iomap().
* */
void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned long maxlen)
{
@@ -127,6 +141,10 @@ EXPORT_SYMBOL(pci_iomap);
*
* @maxlen specifies the maximum length to map. If you want to get access to
* the complete BAR without checking for its length first, pass %0 here.
+ *
+ * NOTE:
+ * This function is never managed, even if you initialized with
+ * pcim_enable_device().
* */
void __iomem *pci_iomap_wc(struct pci_dev *dev, int bar, unsigned long maxlen)
{
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index b5d21d8207d6..9d9d09534efe 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -3903,6 +3903,8 @@ EXPORT_SYMBOL(pci_release_region);
* @res_name: Name to be associated with resource.
* @exclusive: whether the region access is exclusive or not
*
+ * Returns: 0 on success, negative error code on failure.
+ *
* Mark the PCI region associated with PCI device @pdev BAR @bar as
* being reserved by owner @res_name. Do not access any
* address inside the PCI regions unless this call returns
@@ -3914,6 +3916,13 @@ EXPORT_SYMBOL(pci_release_region);
*
* Returns 0 on success, or %EBUSY on error. A warning
* message is also printed on failure.
+ *
+ * NOTE:
+ * This is a "hybrid" function: Its normally unmanaged, but becomes managed
+ * when pcim_enable_device() has been called in advance.
+ * This hybrid feature is DEPRECATED! If you need to implement a new pci
+ * function that does automatic cleanup, write a new pcim_* function that uses
+ * devres directly.
*/
static int __pci_request_region(struct pci_dev *pdev, int bar,
const char *res_name, int exclusive)
@@ -3962,6 +3971,8 @@ static int __pci_request_region(struct pci_dev *pdev, int bar,
* @bar: BAR to be reserved
* @res_name: Name to be associated with resource
*
+ * Returns: 0 on success, negative error code on failure.
+ *
* Mark the PCI region associated with PCI device @pdev BAR @bar as
* being reserved by owner @res_name. Do not access any
* address inside the PCI regions unless this call returns
@@ -3969,6 +3980,12 @@ static int __pci_request_region(struct pci_dev *pdev, int bar,
*
* Returns 0 on success, or %EBUSY on error. A warning
* message is also printed on failure.
+ *
+ * NOTE:
+ * This is a "hybrid" function: Its normally unmanaged, but becomes managed
+ * when pcim_enable_device() has been called in advance.
+ * This hybrid feature is DEPRECATED! If you want managed cleanup, use the
+ * pcim_* functions instead.
*/
int pci_request_region(struct pci_dev *pdev, int bar, const char *res_name)
{
@@ -3994,6 +4011,13 @@ void pci_release_selected_regions(struct pci_dev *pdev, int bars)
}
EXPORT_SYMBOL(pci_release_selected_regions);

+/*
+ * NOTE:
+ * This is a "hybrid" function: Its normally unmanaged, but becomes managed
+ * when pcim_enable_device() has been called in advance.
+ * This hybrid feature is DEPRECATED! If you want managed cleanup, use the
+ * pcim_* functions instead.
+ */
static int __pci_request_selected_regions(struct pci_dev *pdev, int bars,
const char *res_name, int excl)
{
@@ -4019,6 +4043,14 @@ static int __pci_request_selected_regions(struct pci_dev *pdev, int bars,
* @pdev: PCI device whose resources are to be reserved
* @bars: Bitmask of BARs to be requested
* @res_name: Name to be associated with resource
+ *
+ * Returns: 0 on success, negative error code on failure.
+ *
+ * NOTE:
+ * This is a "hybrid" function: Its normally unmanaged, but becomes managed
+ * when pcim_enable_device() has been called in advance.
+ * This hybrid feature is DEPRECATED! If you want managed cleanup, use the
+ * pcim_* functions instead.
*/
int pci_request_selected_regions(struct pci_dev *pdev, int bars,
const char *res_name)
@@ -4027,6 +4059,20 @@ int pci_request_selected_regions(struct pci_dev *pdev, int bars,
}
EXPORT_SYMBOL(pci_request_selected_regions);

+/**
+ * pci_request_selected_regions_exclusive - Request regions exclusively
+ * @pdev: PCI device to request regions from
+ * @bars: bit mask of bars to request
+ * @res_name: name to be associated with the requests
+ *
+ * Returns: 0 on success, negative error code on failure.
+ *
+ * NOTE:
+ * This is a "hybrid" function: Its normally unmanaged, but becomes managed
+ * when pcim_enable_device() has been called in advance.
+ * This hybrid feature is DEPRECATED! If you want managed cleanup, use the
+ * pcim_* functions instead.
+ */
int pci_request_selected_regions_exclusive(struct pci_dev *pdev, int bars,
const char *res_name)
{
@@ -4044,7 +4090,6 @@ EXPORT_SYMBOL(pci_request_selected_regions_exclusive);
* successful call to pci_request_regions(). Call this function only
* after all use of the PCI regions has ceased.
*/
-
void pci_release_regions(struct pci_dev *pdev)
{
pci_release_selected_regions(pdev, (1 << PCI_STD_NUM_BARS) - 1);
@@ -4076,6 +4121,8 @@ EXPORT_SYMBOL(pci_request_regions);
* @pdev: PCI device whose resources are to be reserved
* @res_name: Name to be associated with resource.
*
+ * Returns: 0 on success, negative error code on failure.
+ *
* Mark all PCI regions associated with PCI device @pdev as being reserved
* by owner @res_name. Do not access any address inside the PCI regions
* unless this call returns successfully.
@@ -4085,6 +4132,12 @@ EXPORT_SYMBOL(pci_request_regions);
*
* Returns 0 on success, or %EBUSY on error. A warning message is also
* printed on failure.
+ *
+ * NOTE:
+ * This is a "hybrid" function: Its normally unmanaged, but becomes managed
+ * when pcim_enable_device() has been called in advance.
+ * This hybrid feature is DEPRECATED! If you want managed cleanup, use the
+ * pcim_* functions instead.
*/
int pci_request_regions_exclusive(struct pci_dev *pdev, const char *res_name)
{
@@ -4416,6 +4469,11 @@ void pci_disable_parity(struct pci_dev *dev)
* @enable: boolean: whether to enable or disable PCI INTx
*
* Enables/disables PCI INTx for device @pdev
+ *
+ * NOTE:
+ * This is a "hybrid" function: Its normally unmanaged, but becomes managed
+ * when pcim_enable_device() has been called in advance.
+ * This hybrid feature is DEPRECATED!
*/
void pci_intx(struct pci_dev *pdev, int enable)
{
--
2.44.0