firewire: core: use xarray instead of idr to maintain client resource

In core function, the instances of some client resource structures are
maintained by IDR. As of kernel v6.0, IDR has been superseded by XArray
and deprecated.

This commit replaces the usage of IDR with XArray to maintain the
resource instances. The instance of XArray is allocated per client with
XA_FLAGS_ALLOC1 so that the index of allocated entry is greater than zero
and returns to user space client as handle of the resource.

Link: https://lore.kernel.org/r/20240812235210.28458-6-o-takashi@sakamocchi.jp
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>

Author: takaswie

drivers/firewire/core-cdev.c

@@ -14,7 +14,6 @@
 #include <linux/errno.h>
 #include <linux/firewire.h>
 #include <linux/firewire-cdev.h>
-#include <linux/idr.h>
 #include <linux/irqflags.h>
 #include <linux/jiffies.h>
 #include <linux/kernel.h>
@@ -54,7 +53,7 @@ struct client {
 
 	spinlock_t lock;
 	bool in_shutdown;
-	struct idr resource_idr;
+	struct xarray resource_xa;
 	struct list_head event_list;
 	wait_queue_head_t wait;
 	wait_queue_head_t tx_flush_wait;
@@ -297,7 +296,7 @@ static int fw_device_op_open(struct inode *inode, struct file *file)
 
 	client->device = device;
 	spin_lock_init(&client->lock);
-	idr_init(&client->resource_idr);
+	xa_init_flags(&client->resource_xa, XA_FLAGS_ALLOC1 | XA_FLAGS_LOCK_BH);
 	INIT_LIST_HEAD(&client->event_list);
 	init_waitqueue_head(&client->wait);
 	init_waitqueue_head(&client->tx_flush_wait);
@@ -407,7 +406,7 @@ static void queue_bus_reset_event(struct client *client)
 {
 	struct bus_reset_event *e;
 	struct client_resource *resource;
-	int id;
+	unsigned long index;
 
 	e = kzalloc(sizeof(*e), GFP_KERNEL);
 	if (e == NULL)
@@ -420,7 +419,7 @@ static void queue_bus_reset_event(struct client *client)
 
 	guard(spinlock_irq)(&client->lock);
 
-	idr_for_each_entry(&client->resource_idr, resource, id) {
+	xa_for_each(&client->resource_xa, index, resource) {
 		if (is_iso_resource(resource))
 			schedule_iso_resource(to_iso_resource(resource), 0);
 	}
@@ -501,49 +500,52 @@ static int ioctl_get_info(struct client *client, union ioctl_arg *arg)
 	return ret ? -EFAULT : 0;
 }
 
-static int add_client_resource(struct client *client,
-			       struct client_resource *resource, gfp_t gfp_mask)
+static int add_client_resource(struct client *client, struct client_resource *resource,
+			       gfp_t gfp_mask)
 {
-	bool preload = gfpflags_allow_blocking(gfp_mask);
 	int ret;
 
-	if (preload)
-		idr_preload(gfp_mask);
-
 	scoped_guard(spinlock_irqsave, &client->lock) {
-		if (client->in_shutdown)
+		u32 index;
+
+		if (client->in_shutdown) {
 			ret = -ECANCELED;
-		else
-			ret = idr_alloc(&client->resource_idr, resource, 0, 0, GFP_NOWAIT);
+		} else {
+			if (gfpflags_allow_blocking(gfp_mask)) {
+				ret = xa_alloc(&client->resource_xa, &index, resource, xa_limit_32b,
+					       GFP_NOWAIT);
+			} else {
+				ret = xa_alloc_bh(&client->resource_xa, &index, resource,
+						  xa_limit_32b, GFP_NOWAIT);
+			}
+		}
 		if (ret >= 0) {
-			resource->handle = ret;
+			resource->handle = index;
 			client_get(client);
 			if (is_iso_resource(resource))
 				schedule_iso_resource(to_iso_resource(resource), 0);
 		}
 	}
 
-	if (preload)
-		idr_preload_end();
-
 	return ret < 0 ? ret : 0;
 }
 
 static int release_client_resource(struct client *client, u32 handle,
 				   client_resource_release_fn_t release,
 				   struct client_resource **return_resource)
 {
+	unsigned long index = handle;
 	struct client_resource *resource;
 
 	scoped_guard(spinlock_irq, &client->lock) {
 		if (client->in_shutdown)
 			return -EINVAL;
 
-		resource = idr_find(&client->resource_idr, handle);
+		resource = xa_load(&client->resource_xa, index);
 		if (!resource || resource->release != release)
 			return -EINVAL;
 
-		idr_remove(&client->resource_idr, handle);
+		xa_erase(&client->resource_xa, handle);
 	}
 
 	if (return_resource)
@@ -566,9 +568,10 @@ static void complete_transaction(struct fw_card *card, int rcode, u32 request_ts
 {
 	struct outbound_transaction_event *e = data;
 	struct client *client = e->client;
+	unsigned long index = e->r.resource.handle;
 
 	scoped_guard(spinlock_irqsave, &client->lock) {
-		idr_remove(&client->resource_idr, e->r.resource.handle);
+		xa_erase(&client->resource_xa, index);
 		if (client->in_shutdown)
 			wake_up(&client->tx_flush_wait);
 	}
@@ -619,7 +622,7 @@ static void complete_transaction(struct fw_card *card, int rcode, u32 request_ts
 		break;
 	}
 
-	/* Drop the idr's reference */
+	// Drop the xarray's reference.
 	client_put(client);
 }
 
@@ -1317,6 +1320,7 @@ static void iso_resource_work(struct work_struct *work)
 	struct iso_resource *r =
 			container_of(work, struct iso_resource, work.work);
 	struct client *client = r->client;
+	unsigned long index = r->resource.handle;
 	int generation, channel, bandwidth, todo;
 	bool skip, free, success;
 
@@ -1351,7 +1355,7 @@ static void iso_resource_work(struct work_struct *work)
 			todo == ISO_RES_ALLOC_ONCE);
 	/*
 	 * Is this generation outdated already?  As long as this resource sticks
-	 * in the idr, it will be scheduled again for a newer generation or at
+	 * in the xarray, it will be scheduled again for a newer generation or at
 	 * shutdown.
 	 */
 	if (channel == -EAGAIN &&
@@ -1366,10 +1370,10 @@ static void iso_resource_work(struct work_struct *work)
 		if (r->todo == ISO_RES_ALLOC)
 			r->todo = ISO_RES_REALLOC;
 		// Allocation or reallocation failure?  Pull this resource out of the
-		// idr and prepare for deletion, unless the client is shutting down.
+		// xarray and prepare for deletion, unless the client is shutting down.
 		if (r->todo == ISO_RES_REALLOC && !success &&
 		    !client->in_shutdown &&
-		    idr_remove(&client->resource_idr, r->resource.handle)) {
+		    xa_erase(&client->resource_xa, index)) {
 			client_put(client);
 			free = true;
 		}
@@ -1839,11 +1843,11 @@ static int fw_device_op_mmap(struct file *file, struct vm_area_struct *vma)
 static bool has_outbound_transactions(struct client *client)
 {
 	struct client_resource *resource;
-	int id;
+	unsigned long index;
 
 	guard(spinlock_irq)(&client->lock);
 
-	idr_for_each_entry(&client->resource_idr, resource, id) {
+	xa_for_each(&client->resource_xa, index, resource) {
 		if (is_outbound_transaction_resource(resource))
 			return true;
 	}
@@ -1856,7 +1860,7 @@ static int fw_device_op_release(struct inode *inode, struct file *file)
 	struct client *client = file->private_data;
 	struct event *event, *next_event;
 	struct client_resource *resource;
-	int id;
+	unsigned long index;
 
 	scoped_guard(spinlock_irq, &client->device->card->lock)
 		list_del(&client->phy_receiver_link);
@@ -1870,17 +1874,17 @@ static int fw_device_op_release(struct inode *inode, struct file *file)
 	if (client->buffer.pages)
 		fw_iso_buffer_destroy(&client->buffer, client->device->card);
 
-	/* Freeze client->resource_idr and client->event_list */
+	// Freeze client->resource_xa and client->event_list.
 	scoped_guard(spinlock_irq, &client->lock)
 		client->in_shutdown = true;
 
 	wait_event(client->tx_flush_wait, !has_outbound_transactions(client));
 
-	idr_for_each_entry(&client->resource_idr, resource, id) {
+	xa_for_each(&client->resource_xa, index, resource) {
 		resource->release(client, resource);
 		client_put(client);
 	}
-	idr_destroy(&client->resource_idr);
+	xa_destroy(&client->resource_xa);
 
 	list_for_each_entry_safe(event, next_event, &client->event_list, link)
 		kfree(event);

drivers/firewire/core.h

@@ -7,7 +7,6 @@
 #include <linux/dma-mapping.h>
 #include <linux/fs.h>
 #include <linux/list.h>
-#include <linux/idr.h>
 #include <linux/xarray.h>
 #include <linux/mm_types.h>
 #include <linux/rwsem.h>