[dpdk-dev] [PATCH v3 3/3] pci: Clarify interfaces for dynamic attach/detach of drivers

[Ben Walker <benjamin.walker@intel.com>]

There are now two functions - rte_eal_pci_attach_driver and
rte_eal_pci_detach_driver - that dynamically attempt to attach
and detach drivers from PCI devices. These only control
whether a registered PCI driver is loaded or not - they are
independent of whether the PCI device exists on the system.

Signed-off-by: Ben Walker <benjamin.walker@intel.com>
---

This patch was previously the fourth in the series, behind
another more controversial change. That change has been
removed and this patch was reordered to be independent
of those changes.

 lib/librte_eal/common/eal_common_dev.c  |   4 +-
 lib/librte_eal/common/eal_common_pci.c  | 109 +++++++++-----------------------
 lib/librte_eal/common/include/rte_pci.h |  22 ++++---
 3 files changed, 43 insertions(+), 92 deletions(-)

diff --git a/lib/librte_eal/common/eal_common_dev.c b/lib/librte_eal/common/eal_common_dev.c
index 4f3b493..1c6834e 100644
--- a/lib/librte_eal/common/eal_common_dev.c
+++ b/lib/librte_eal/common/eal_common_dev.c
@@ -114,7 +114,7 @@ int rte_eal_dev_attach(const char *name, const char *devargs)
 	}
 
 	if (eal_parse_pci_DomBDF(name, &addr) == 0) {
-		if (rte_eal_pci_probe_one(&addr) < 0)
+		if (rte_eal_pci_attach_driver(&addr) < 0)
 			goto err;
 
 	} else {
@@ -139,7 +139,7 @@ int rte_eal_dev_detach(const char *name)
 	}
 
 	if (eal_parse_pci_DomBDF(name, &addr) == 0) {
-		if (rte_eal_pci_detach(&addr) < 0)
+		if (rte_eal_pci_detach_driver(&addr) < 0)
 			goto err;
 	} else {
 		if (rte_eal_vdev_uninit(name))
diff --git a/lib/librte_eal/common/eal_common_pci.c b/lib/librte_eal/common/eal_common_pci.c
index 72547bd..00668b6 100644
--- a/lib/librte_eal/common/eal_common_pci.c
+++ b/lib/librte_eal/common/eal_common_pci.c
@@ -222,59 +222,36 @@ rte_eal_pci_probe_one_driver(struct rte_pci_driver *dr, struct rte_pci_device *d
 	return 1;
 }
 
-/*
- * If vendor/device ID match, call the remove() function of the
- * driver.
- */
 static int
-rte_eal_pci_detach_dev(struct rte_pci_driver *dr,
-		struct rte_pci_device *dev)
+rte_eal_pci_remove_driver(struct rte_pci_device *dev)
 {
-	const struct rte_pci_id *id_table;
+	struct rte_pci_driver *driver;
+	struct rte_pci_addr *loc;
 
-	if ((dr == NULL) || (dev == NULL))
-		return -EINVAL;
+	loc = &dev->addr;
+	driver = dev->driver;
 
-	for (id_table = dr->id_table; id_table->vendor_id != 0; id_table++) {
-
-		/* check if device's identifiers match the driver's ones */
-		if (id_table->vendor_id != dev->id.vendor_id &&
-				id_table->vendor_id != PCI_ANY_ID)
-			continue;
-		if (id_table->device_id != dev->id.device_id &&
-				id_table->device_id != PCI_ANY_ID)
-			continue;
-		if (id_table->subsystem_vendor_id != dev->id.subsystem_vendor_id &&
-				id_table->subsystem_vendor_id != PCI_ANY_ID)
-			continue;
-		if (id_table->subsystem_device_id != dev->id.subsystem_device_id &&
-				id_table->subsystem_device_id != PCI_ANY_ID)
-			continue;
-
-		struct rte_pci_addr *loc = &dev->addr;
+	if (driver == NULL)
+		return 0;
 
-		RTE_LOG(DEBUG, EAL, "PCI device "PCI_PRI_FMT" on NUMA socket %i\n",
-				loc->domain, loc->bus, loc->devid,
-				loc->function, dev->device.numa_node);
+	RTE_LOG(DEBUG, EAL, "PCI device "PCI_PRI_FMT" on NUMA socket %i\n",
+			loc->domain, loc->bus, loc->devid,
+			loc->function, dev->device.numa_node);
 
-		RTE_LOG(DEBUG, EAL, "  remove driver: %x:%x %s\n", dev->id.vendor_id,
-				dev->id.device_id, dr->driver.name);
+	RTE_LOG(DEBUG, EAL, "  remove driver: %x:%x %s\n", dev->id.vendor_id,
+			dev->id.device_id, driver->driver.name);
 
-		if (dr->remove && (dr->remove(dev) < 0))
-			return -1;	/* negative value is an error */
+	if (driver->remove && (driver->remove(dev) < 0))
+		return -1;	/* negative value is an error */
 
-		/* clear driver structure */
-		dev->driver = NULL;
+	/* clear driver structure */
+	dev->driver = NULL;
 
-		if (dr->drv_flags & RTE_PCI_DRV_NEED_MAPPING)
-			/* unmap resources for devices that use igb_uio */
-			rte_eal_pci_unmap_device(dev);
+	if (driver->drv_flags & RTE_PCI_DRV_NEED_MAPPING)
+		/* unmap resources for devices that use igb_uio */
+		rte_eal_pci_unmap_device(dev);
 
-		return 0;
-	}
-
-	/* return positive value if driver doesn't support this device */
-	return 1;
+	return 0;
 }
 
 /*
@@ -309,38 +286,11 @@ pci_probe_all_drivers(struct rte_pci_device *dev)
 }
 
 /*
- * If vendor/device ID match, call the remove() function of all
- * registered driver for the given device. Return -1 if initialization
- * failed, return 1 if no driver is found for this device.
- */
-static int
-pci_detach_all_drivers(struct rte_pci_device *dev)
-{
-	struct rte_pci_driver *dr = NULL;
-	int rc = 0;
-
-	if (dev == NULL)
-		return -1;
-
-	TAILQ_FOREACH(dr, &pci_driver_list, next) {
-		rc = rte_eal_pci_detach_dev(dr, dev);
-		if (rc < 0)
-			/* negative value is an error */
-			return -1;
-		if (rc > 0)
-			/* positive value means driver doesn't support it */
-			continue;
-		return 0;
-	}
-	return 1;
-}
-
-/*
  * Find the pci device specified by pci address, then invoke probe function of
  * the driver of the devive.
  */
 int
-rte_eal_pci_probe_one(const struct rte_pci_addr *addr)
+rte_eal_pci_attach_driver(const struct rte_pci_addr *addr)
 {
 	struct rte_pci_device *dev = NULL;
 	int ret = 0;
@@ -376,10 +326,9 @@ rte_eal_pci_probe_one(const struct rte_pci_addr *addr)
  * Detach device specified by its pci address.
  */
 int
-rte_eal_pci_detach(const struct rte_pci_addr *addr)
+rte_eal_pci_detach_driver(const struct rte_pci_addr *addr)
 {
 	struct rte_pci_device *dev = NULL;
-	int ret = 0;
 
 	if (addr == NULL)
 		return -1;
@@ -388,17 +337,17 @@ rte_eal_pci_detach(const struct rte_pci_addr *addr)
 		if (rte_eal_compare_pci_addr(&dev->addr, addr))
 			continue;
 
-		ret = pci_detach_all_drivers(dev);
-		if (ret < 0)
-			goto err_return;
+		if (dev->driver == NULL) {
+			/* The device at that address does not have a driver loaded */
+			return 0;
+		}
+
+		if (rte_eal_pci_remove_driver(dev) < 0)
+			return -1;
 
-		TAILQ_REMOVE(&pci_device_list, dev, next);
-		free(dev);
 		return 0;
 	}
-	return -1;
 
-err_return:
 	RTE_LOG(WARNING, EAL, "Requested device " PCI_PRI_FMT
 			" cannot be used\n", dev->addr.domain, dev->addr.bus,
 			dev->addr.devid, dev->addr.function);
diff --git a/lib/librte_eal/common/include/rte_pci.h b/lib/librte_eal/common/include/rte_pci.h
index 5640896..c285fd4 100644
--- a/lib/librte_eal/common/include/rte_pci.h
+++ b/lib/librte_eal/common/include/rte_pci.h
@@ -470,11 +470,14 @@ void *pci_map_resource(void *requested_addr, int fd, off_t offset,
 void pci_unmap_resource(void *requested_addr, size_t size);
 
 /**
- * Probe the single PCI device.
+ * Attempt to load the registered driver for the PCI device at addr.
  *
- * Scan the content of the PCI bus, and find the pci device specified by pci
- * address, then call the probe() function for registered driver that has a
- * matching entry in its id_table for discovered device.
+ * Find the pci device specified by addr, then call the probe() function
+ * for each registered driver that has a matching entry in its id_table until
+ * the correct driver is found.
+ *
+ * If the PCI address is known, this is considerably more efficient than
+ * calling rte_eal_pci_probe.
  *
  * @param addr
  *	The PCI Bus-Device-Function address to probe.
@@ -482,14 +485,13 @@ void pci_unmap_resource(void *requested_addr, size_t size);
  *   - 0 on success.
  *   - Negative on error.
  */
-int rte_eal_pci_probe_one(const struct rte_pci_addr *addr);
+int rte_eal_pci_attach_driver(const struct rte_pci_addr *addr);
 
 /**
- * Close the single PCI device.
+ * Unload the driver for the PCI device at addr.
  *
- * Scan the content of the PCI bus, and find the pci device specified by pci
- * address, then call the remove() function for registered driver that has a
- * matching entry in its id_table for discovered device.
+ * Find the pci device specified by addr, then call the remove() function
+ * for the currently loaded driver.
  *
  * @param addr
  *	The PCI Bus-Device-Function address to close.
@@ -497,7 +499,7 @@ int rte_eal_pci_probe_one(const struct rte_pci_addr *addr);
  *   - 0 on success.
  *   - Negative on error.
  */
-int rte_eal_pci_detach(const struct rte_pci_addr *addr);
+int rte_eal_pci_detach_driver(const struct rte_pci_addr *addr);
 
 /**
  * Dump the content of the PCI bus.
-- 
2.9.3