staging: unisys: visorhba: Convert module from IDR to XArray

Converted visorhba from IDR to XArray. The abstract data type XArray is
more memory-efficient, parallelizable, and cache friendly. It takes
advantage of RCU to perform lookups without locking. Furthermore, IDR is
deprecated because XArray has a better (cleaner and more consistent)
API.

Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Link: https://lore.kernel.org/r/20210514081112.19542-1-fmdefrancesco@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/unisys/visorhba/visorhba_main.c b/drivers/staging/unisys/visorhba/visorhba_main.c
index 4455d26..41f8a72 100644 (file)
--- a/drivers/staging/unisys/visorhba/visorhba_main.c
+++ b/drivers/staging/unisys/visorhba/visorhba_main.c
@@ -6,10 +6,10 @@
 
 #include <linux/debugfs.h>
 #include <linux/kthread.h>
-#include <linux/idr.h>
 #include <linux/module.h>
 #include <linux/seq_file.h>
 #include <linux/visorbus.h>
+#include <linux/xarray.h>
 #include <scsi/scsi.h>
 #include <scsi/scsi_host.h>
 #include <scsi/scsi_cmnd.h>
@@ -82,8 +82,7 @@ struct visorhba_devdata {
         * allows us to pass int handles back-and-forth between us and
         * iovm, instead of raw pointers
         */
-       struct idr idr;
-
+       struct xarray xa;
        struct dentry *debugfs_dir;
        struct dentry *debugfs_info;
 };
@@ -182,71 +181,48 @@ static struct uiscmdrsp *get_scsipending_cmdrsp(struct visorhba_devdata *ddata,
        return NULL;
 }
 
-/*
- * simple_idr_get - Associate a provided pointer with an int value
- *                 1 <= value <= INT_MAX, and return this int value;
- *                 the pointer value can be obtained later by passing
- *                 this int value to idr_find()
- * @idrtable: The data object maintaining the pointer<-->int mappings
- * @p:       The pointer value to be remembered
- * @lock:     A spinlock used when exclusive access to idrtable is needed
- *
- * Return: The id number mapped to pointer 'p', 0 on failure
- */
-static unsigned int simple_idr_get(struct idr *idrtable, void *p,
-                                  spinlock_t *lock)
-{
-       int id;
-       unsigned long flags;
-
-       idr_preload(GFP_KERNEL);
-       spin_lock_irqsave(lock, flags);
-       id = idr_alloc(idrtable, p, 1, INT_MAX, GFP_NOWAIT);
-       spin_unlock_irqrestore(lock, flags);
-       idr_preload_end();
-       /* failure */
-       if (id < 0)
-               return 0;
-       /* idr_alloc() guarantees > 0 */
-       return (unsigned int)(id);
-}
-
 /*
  * setup_scsitaskmgmt_handles - Stash the necessary handles so that the
  *                             completion processing logic for a taskmgmt
  *                             cmd will be able to find who to wake up
  *                             and where to stash the result
- * @idrtable: The data object maintaining the pointer<-->int mappings
- * @lock:     A spinlock used when exclusive access to idrtable is needed
+ * @xa:       The data object maintaining the pointer<-->int mappings
  * @cmdrsp:   Response from the IOVM
  * @event:    The event handle to associate with an id
  * @result:   The location to place the result of the event handle into
  */
-static void setup_scsitaskmgmt_handles(struct idr *idrtable, spinlock_t *lock,
-                                      struct uiscmdrsp *cmdrsp,
+static int setup_scsitaskmgmt_handles(struct xarray *xa, struct uiscmdrsp *cmdrsp,
                                       wait_queue_head_t *event, int *result)
 {
-       /* specify the event that has to be triggered when this */
-       /* cmd is complete */
-       cmdrsp->scsitaskmgmt.notify_handle =
-               simple_idr_get(idrtable, event, lock);
-       cmdrsp->scsitaskmgmt.notifyresult_handle =
-               simple_idr_get(idrtable, result, lock);
+       int ret;
+       u32 id;
+
+       /* specify the event that has to be triggered when this cmd is complete */
+       ret = xa_alloc_irq(xa, &id, event, xa_limit_32b, GFP_KERNEL);
+       if (ret)
+               return ret;
+       cmdrsp->scsitaskmgmt.notify_handle = id;
+       ret = xa_alloc_irq(xa, &id, result, xa_limit_32b, GFP_KERNEL);
+       if (ret) {
+               xa_erase_irq(xa, cmdrsp->scsitaskmgmt.notify_handle);
+               return ret;
+       }
+       cmdrsp->scsitaskmgmt.notifyresult_handle = id;
+
+       return 0;
 }
 
 /*
  * cleanup_scsitaskmgmt_handles - Forget handles created by
  *                               setup_scsitaskmgmt_handles()
- * @idrtable: The data object maintaining the pointer<-->int mappings
+ * @xa: The data object maintaining the pointer<-->int mappings
  * @cmdrsp:   Response from the IOVM
  */
-static void cleanup_scsitaskmgmt_handles(struct idr *idrtable,
+static void cleanup_scsitaskmgmt_handles(struct xarray *xa,
                                         struct uiscmdrsp *cmdrsp)
 {
-       if (cmdrsp->scsitaskmgmt.notify_handle)
-               idr_remove(idrtable, cmdrsp->scsitaskmgmt.notify_handle);
-       if (cmdrsp->scsitaskmgmt.notifyresult_handle)
-               idr_remove(idrtable, cmdrsp->scsitaskmgmt.notifyresult_handle);
+       xa_erase_irq(xa, cmdrsp->scsitaskmgmt.notify_handle);
+       xa_erase_irq(xa, cmdrsp->scsitaskmgmt.notifyresult_handle);
 }
 
 /*
@@ -269,6 +245,7 @@ static int forward_taskmgmt_command(enum task_mgmt_types tasktype,
        int notifyresult = 0xffff;
        wait_queue_head_t notifyevent;
        int scsicmd_id;
+       int ret;
 
        if (devdata->serverdown || devdata->serverchangingstate)
                return FAILED;
@@ -284,8 +261,14 @@ static int forward_taskmgmt_command(enum task_mgmt_types tasktype,
 
        /* issue TASK_MGMT_ABORT_TASK */
        cmdrsp->cmdtype = CMD_SCSITASKMGMT_TYPE;
-       setup_scsitaskmgmt_handles(&devdata->idr, &devdata->privlock, cmdrsp,
-                                  &notifyevent, &notifyresult);
+
+       ret = setup_scsitaskmgmt_handles(&devdata->xa, cmdrsp,
+                                        &notifyevent, &notifyresult);
+       if (ret) {
+               dev_dbg(&scsidev->sdev_gendev,
+                       "visorhba: setup_scsitaskmgmt_handles returned %d\n", ret);
+               return FAILED;
+       }
 
        /* save destination */
        cmdrsp->scsitaskmgmt.tasktype = tasktype;
@@ -311,14 +294,14 @@ static int forward_taskmgmt_command(enum task_mgmt_types tasktype,
        dev_dbg(&scsidev->sdev_gendev,
                "visorhba: taskmgmt type=%d success; result=0x%x\n",
                 tasktype, notifyresult);
-       cleanup_scsitaskmgmt_handles(&devdata->idr, cmdrsp);
+       cleanup_scsitaskmgmt_handles(&devdata->xa, cmdrsp);
        return SUCCESS;
 
 err_del_scsipending_ent:
        dev_dbg(&scsidev->sdev_gendev,
                "visorhba: taskmgmt type=%d not executed\n", tasktype);
        del_scsipending_ent(devdata, scsicmd_id);
-       cleanup_scsitaskmgmt_handles(&devdata->idr, cmdrsp);
+       cleanup_scsitaskmgmt_handles(&devdata->xa, cmdrsp);
        return FAILED;
 }
 
@@ -654,13 +637,13 @@ DEFINE_SHOW_ATTRIBUTE(info_debugfs);
  * Service Partition returned the result of the task management
  * command. Wake up anyone waiting for it.
  */
-static void complete_taskmgmt_command(struct idr *idrtable,
+static void complete_taskmgmt_command(struct xarray *xa,
                                      struct uiscmdrsp *cmdrsp, int result)
 {
        wait_queue_head_t *wq =
-               idr_find(idrtable, cmdrsp->scsitaskmgmt.notify_handle);
+               xa_load(xa, cmdrsp->scsitaskmgmt.notify_handle);
        int *scsi_result_ptr =
-               idr_find(idrtable, cmdrsp->scsitaskmgmt.notifyresult_handle);
+               xa_load(xa, cmdrsp->scsitaskmgmt.notifyresult_handle);
        if (unlikely(!(wq && scsi_result_ptr))) {
                pr_err("visorhba: no completion context; cmd will time out\n");
                return;
@@ -708,7 +691,7 @@ static void visorhba_serverdown_complete(struct visorhba_devdata *devdata)
                        break;
                case CMD_SCSITASKMGMT_TYPE:
                        cmdrsp = pendingdel->sent;
-                       complete_taskmgmt_command(&devdata->idr, cmdrsp,
+                       complete_taskmgmt_command(&devdata->xa, cmdrsp,
                                                  TASK_MGMT_FAILED);
                        break;
                default:
@@ -905,7 +888,7 @@ static void drain_queue(struct uiscmdrsp *cmdrsp,
                        if (!del_scsipending_ent(devdata,
                                                 cmdrsp->scsitaskmgmt.handle))
                                break;
-                       complete_taskmgmt_command(&devdata->idr, cmdrsp,
+                       complete_taskmgmt_command(&devdata->xa, cmdrsp,
                                                  cmdrsp->scsitaskmgmt.result);
                } else if (cmdrsp->cmdtype == CMD_NOTIFYGUEST_TYPE)
                        dev_err_once(&devdata->dev->device,
@@ -1053,7 +1036,7 @@ static int visorhba_probe(struct visor_device *dev)
        if (err)
                goto err_debugfs_info;
 
-       idr_init(&devdata->idr);
+       xa_init(&devdata->xa);
 
        devdata->cmdrsp = kmalloc(sizeof(*devdata->cmdrsp), GFP_ATOMIC);
        visorbus_enable_channel_interrupts(dev);
@@ -1096,8 +1079,6 @@ static void visorhba_remove(struct visor_device *dev)
        scsi_remove_host(scsihost);
        scsi_host_put(scsihost);
 
-       idr_destroy(&devdata->idr);
-
        dev_set_drvdata(&dev->device, NULL);
        debugfs_remove(devdata->debugfs_info);
        debugfs_remove_recursive(devdata->debugfs_dir);