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From: Philipp Stanner <pstanner@redhat.com>
To: Jonathan Corbet <corbet@lwn.net>,
	Hans de Goede <hdegoede@redhat.com>,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	Maxime Ripard <mripard@kernel.org>,
	Thomas Zimmermann <tzimmermann@suse.de>,
	David Airlie <airlied@gmail.com>,
	Daniel Vetter <daniel@ffwll.ch>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Philipp Stanner <pstanner@redhat.com>,
	Sam Ravnborg <sam@ravnborg.org>,
	dakr@redhat.com
Cc: linux-doc@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	dri-devel@lists.freedesktop.org,
	linux-pci@vger.kernel.org
Subject: [PATCH 04/10] pci: devres: make devres region requests consistent
Date: Mon, 15 Jan 2024 15:46:15 +0100
Message-ID: <20240115144655.32046-6-pstanner@redhat.com>
In-Reply-To: <20240115144655.32046-2-pstanner@redhat.com>
References: <20240115144655.32046-2-pstanner@redhat.com>
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Now that pure managed region request functions are available, the
implementation of the hybrid-functions which are only sometimes managed
can be made more consistent and readable by wrapping those
always-managed functions.

Implement a new pcim_ function for exclusively requested regions.
Have the pci_request / release functions call their pcim_ counterparts.
Remove the now surplus region_mask from the devres struct.

Signed-off-by: Philipp Stanner <pstanner@redhat.com>
---
 drivers/pci/devres.c | 49 ++++++++++++++++++++++---------------------
 drivers/pci/pci.c    | 50 +++++++++++++++-----------------------------
 drivers/pci/pci.h    |  6 ------
 include/linux/pci.h  |  1 +
 4 files changed, 43 insertions(+), 63 deletions(-)

diff --git a/drivers/pci/devres.c b/drivers/pci/devres.c
index e221919ebbe2..1e5cf950775d 100644
--- a/drivers/pci/devres.c
+++ b/drivers/pci/devres.c
@@ -22,18 +22,15 @@
  *    _sometimes_ managed (e.g. pci_request_region()).
  *    Consequently, in the new API, region requests performed by the pcim_
  *    functions are automatically cleaned up through the devres callback
- *    pcim_addr_resource_release(), while requests performed by
- *    pcim_enable_device() + pci_*region*() are automatically cleaned up
- *    through the for-loop in pcim_release().
+ *    pcim_addr_resource_release().
+ *    Users utilizing pcim_enable_device() + pci_*region*() are redirected in
+ *    pci.c to the managed functions here in this file. This isn't exactly
+ *    perfect, but the only alternative way would be to port ALL drivers using
+ *    said combination to pcim_ functions.
  *
- * TODO 1:
+ * TODO:
  * Remove the legacy table entirely once all calls to pcim_iomap_table() in
  * the kernel have been removed.
- *
- * TODO 2:
- * Port everyone calling pcim_enable_device() + pci_*region*() to using the
- * pcim_ functions. Then, remove all devres functionality from pci_*region*()
- * functions and remove the associated cleanups described above in point #2.
  */
 
 /*
@@ -407,21 +404,6 @@ static void pcim_release(struct device *gendev, void *res)
 {
 	struct pci_dev *dev = to_pci_dev(gendev);
 	struct pci_devres *this = res;
-	int i;
-
-	/*
-	 * This is legacy code.
-	 * All regions requested by a pcim_ function do get released through
-	 * pcim_addr_resource_release(). Thanks to the hybrid nature of the pci_
-	 * region-request functions, this for-loop has to release the regions
-	 * if they have been requested by such a function.
-	 *
-	 * TODO: Remove this once all users of pcim_enable_device() PLUS
-	 * pci-region-request-functions have been ported to pcim_ functions.
-	 */
-	for (i = 0; i < DEVICE_COUNT_RESOURCE; i++)
-		if (this->region_mask & (1 << i))
-			pci_release_region(dev, i);
 
 	if (this->mwi)
 		pci_clear_mwi(dev);
@@ -971,6 +953,25 @@ int pcim_request_region(struct pci_dev *pdev, int bar, const char *name)
 }
 EXPORT_SYMBOL(pcim_request_region);
 
+/**
+ * pcim_request_region_exclusive - Request a PCI BAR exclusively
+ * @pdev: PCI device to requestion region for
+ * @bar: Index of BAR to request
+ * @name: Name associated with the request
+ *
+ * Returns: 0 on success, a negative error code on failure.
+ *
+ * Request region specified by @bar exclusively.
+ *
+ * The region will automatically be released on driver detach. If desired,
+ * release manually only with pcim_release_region().
+ */
+int pcim_request_region_exclusive(struct pci_dev *pdev, int bar, const char *name)
+{
+	return _pcim_request_region(pdev, bar, name, IORESOURCE_EXCLUSIVE);
+}
+EXPORT_SYMBOL(pcim_request_region_exclusive);
+
 /**
  * pcim_release_region - Release a PCI BAR
  * @pdev: PCI device to operate on
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 7ca860acf351..66639dd754c7 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -3873,7 +3873,15 @@ EXPORT_SYMBOL_GPL(pci_common_swizzle);
  */
 void pci_release_region(struct pci_dev *pdev, int bar)
 {
-	struct pci_devres *dr;
+	/*
+	 * This is done for backwards compatibility, because the old pci-devres
+	 * API had a mode in which the function became managed if it had been
+	 * enabled with pcim_enable_device() instead of pci_enable_device().
+	 */
+	if (pci_is_managed(pdev)) {
+		pcim_release_region(pdev, bar);
+		return;
+	}
 
 	if (pci_resource_len(pdev, bar) == 0)
 		return;
@@ -3883,20 +3891,6 @@ void pci_release_region(struct pci_dev *pdev, int bar)
 	else if (pci_resource_flags(pdev, bar) & IORESOURCE_MEM)
 		release_mem_region(pci_resource_start(pdev, bar),
 				pci_resource_len(pdev, bar));
-
-	/*
-	 * This devres utility makes this function sometimes managed
-	 * (when pcim_enable_device() has been called before).
-	 * This is bad because it conflicts with the pcim_ functions being
-	 * exclusively responsible for managed pci. Its "sometimes yes, sometimes
-	 * no" nature can cause bugs.
-	 *
-	 * TODO: Remove this once all users that use pcim_enable_device() PLUS
-	 * a region request function have been ported to using pcim_ functions.
-	 */
-	dr = find_pci_dr(pdev);
-	if (dr)
-		dr->region_mask &= ~(1 << bar);
 }
 EXPORT_SYMBOL(pci_release_region);
 
@@ -3924,14 +3918,18 @@ EXPORT_SYMBOL(pci_release_region);
  * 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.
+ * This hybrid feature is DEPRECATED! If you want managed cleanup, use the
+ * pcim_* functions instead.
  */
 static int __pci_request_region(struct pci_dev *pdev, int bar,
 				const char *res_name, int exclusive)
 {
-	struct pci_devres *dr;
+	if (pci_is_managed(pdev)) {
+		if (exclusive == IORESOURCE_EXCLUSIVE)
+			return pcim_request_region_exclusive(pdev, bar, res_name);
+		else
+			return pcim_request_region(pdev, bar, res_name);
+	}
 
 	if (pci_resource_len(pdev, bar) == 0)
 		return 0;
@@ -3947,20 +3945,6 @@ static int __pci_request_region(struct pci_dev *pdev, int bar,
 			goto err_out;
 	}
 
-	/*
-	 * This devres utility makes this function sometimes managed
-	 * (when pcim_enable_device() has been called before).
-	 * This is bad because it conflicts with the pcim_ functions being
-	 * exclusively responsible for managed pci. Its "sometimes yes, sometimes
-	 * no" nature can cause bugs.
-	 *
-	 * TODO: Remove this once all users that use pcim_enable_device() PLUS
-	 * a region request function have been ported to using pcim_ functions.
-	 */
-	dr = find_pci_dr(pdev);
-	if (dr)
-		dr->region_mask |= 1 << bar;
-
 	return 0;
 
 err_out:
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 4d4bcc2d850f..7c2181677760 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -814,12 +814,6 @@ struct pci_devres {
 	unsigned int orig_intx:1;
 	unsigned int restore_intx:1;
 	unsigned int mwi:1;
-
-	/*
-	 * TODO: remove the region_mask once everyone calling
-	 * pcim_enable_device() + pci_*region*() is ported to pcim_ functions.
-	 */
-	u32 region_mask;
 };
 
 struct pci_devres *find_pci_dr(struct pci_dev *pdev);
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 3dcd8a5e10b5..641ee30f7d2d 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -2321,6 +2321,7 @@ int pcim_iomap_regions_request_all(struct pci_dev *pdev, int mask,
 				   const char *name);
 void pcim_iounmap_regions(struct pci_dev *pdev, int mask);
 int pcim_request_region(struct pci_dev *pdev, int bar, const char *res_name);
+int pcim_request_region_exclusive(struct pci_dev *pdev, int bar, const char *name);
 void pcim_release_region(struct pci_dev *pdev, int bar);
 void pcim_release_all_regions(struct pci_dev *pdev);
 int pcim_request_all_regions(struct pci_dev *pdev, const char *name);
-- 
2.43.0