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.
Signed-off-by: Fabio M. De Francesco <[email protected]>
---
Changes from v5: As suggested by Matthew Wilcox, reworded the commit
message, modified setup_scsitaskmgmt_handles() to manage and return errors,
used 'xa_limit_32b' as the range of indexes (because there is no need to
use 0 as a marker of no allocation).
Changes from v4: Fixed some issues detected by Matthew Wilcox and Fabio
Aiuto.
Changes from v3: Matthew Wilcox found that the XArray was not
initialized: now it is. Changed types handles from u64 to u32 because
they can't work as arguments of xa_alloc_irq() and u32 is enough large
for storing XArray indexes.
Changes from v2: Some residual errors from v1 were not fixed in v2. Now
they have been removed.
Changes from v1: After a first review by Matthew Wilcox, who found a
series of errors and gave suggestions on how to fix them, I rewrote a
larger part of the patch.
.../staging/unisys/visorhba/visorhba_main.c | 103 ++++++++----------
1 file changed, 45 insertions(+), 58 deletions(-)
diff --git a/drivers/staging/unisys/visorhba/visorhba_main.c b/drivers/staging/unisys/visorhba/visorhba_main.c
index 4455d26f7c96..9ed2f1afa642 100644
--- 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>
@@ -82,7 +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 +182,51 @@ 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 == 0)
+ cmdrsp->scsitaskmgmt.notify_handle = id;
+ else
+ return ret;
+
+ ret = xa_alloc_irq(xa, &id, result, xa_limit_32b, GFP_KERNEL);
+ if (ret == 0)
+ cmdrsp->scsitaskmgmt.notifyresult_handle = id;
+ else {
+ xa_erase(xa, cmdrsp->scsitaskmgmt.notify_handle);
+ return ret;
+ }
+
+ return ret;
}
/*
* 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(xa, cmdrsp->scsitaskmgmt.notify_handle);
+ xa_erase(xa, cmdrsp->scsitaskmgmt.notifyresult_handle);
}
/*
@@ -269,6 +249,7 @@ static int forward_taskmgmt_command(enum task_mgmt_types tasktype,
int notifyresult = 0xffff;
wait_queue_head_t notifyevent;
int scsicmd_id;
+ int setup_ret;
if (devdata->serverdown || devdata->serverchangingstate)
return FAILED;
@@ -284,8 +265,16 @@ 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,
+
+ setup_ret = setup_scsitaskmgmt_handles(&devdata->xa, cmdrsp,
¬ifyevent, ¬ifyresult);
+ if (setup_ret < 0) {
+ dev_dbg(&scsidev->sdev_gendev,
+ "visorhba: setup_scsitaskmgmt_handles returned %d\n",
+ setup_ret);
+ return FAILED;
+ }
+
/* save destination */
cmdrsp->scsitaskmgmt.tasktype = tasktype;
@@ -311,14 +300,14 @@ 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 +643,13 @@ 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 +697,7 @@ 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 +894,7 @@ 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 +1042,7 @@ 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 +1085,6 @@ 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);
--
2.31.1
On Tue, May 04, 2021 at 12:07:44PM +0200, Fabio M. De Francesco wrote:
> -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 == 0)
> + cmdrsp->scsitaskmgmt.notify_handle = id;
> + else
> + return ret;
Reverse the condition. Always do error handling, not success handling.
Try keep the success path at one tab indent and the failure path at two
tab indents.
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(xa, cmdrsp->scsitaskmgmt.notify_handle);
return ret;
}
cmdrsp->scsitaskmgmt.notifyresult_handle = id;
> +
> + ret = xa_alloc_irq(xa, &id, result, xa_limit_32b, GFP_KERNEL);
> + if (ret == 0)
> + cmdrsp->scsitaskmgmt.notifyresult_handle = id;
> + else {
> + xa_erase(xa, cmdrsp->scsitaskmgmt.notify_handle);
> + return ret;
> + }
> +
> + return ret;
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(xa, cmdrsp->scsitaskmgmt.notify_handle);
> + xa_erase(xa, cmdrsp->scsitaskmgmt.notifyresult_handle);
> }
>
> /*
> @@ -269,6 +249,7 @@ static int forward_taskmgmt_command(enum task_mgmt_types tasktype,
> int notifyresult = 0xffff;
> wait_queue_head_t notifyevent;
> int scsicmd_id;
> + int setup_ret;
This should be "int ret;". Don't be fancy with the names.
>
> if (devdata->serverdown || devdata->serverchangingstate)
> return FAILED;
> @@ -284,8 +265,16 @@ 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,
> +
> + setup_ret = setup_scsitaskmgmt_handles(&devdata->xa, cmdrsp,
> ¬ifyevent, ¬ifyresult);
> + if (setup_ret < 0) {
You changed setup_scsitaskmgmt_handles() to return non-zero on error so
check for non-zero here. Be consistent.
if (ret)
return FAILED;
> + dev_dbg(&scsidev->sdev_gendev,
> + "visorhba: setup_scsitaskmgmt_handles returned %d\n",
> + setup_ret);
> + return FAILED;
> + }
> +
>
> /* save destination */
> cmdrsp->scsitaskmgmt.tasktype = tasktype;
> @@ -311,14 +300,14 @@ 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 +643,13 @@ 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 +697,7 @@ 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 +894,7 @@ 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 +1042,7 @@ 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 +1085,6 @@ static void visorhba_remove(struct visor_device *dev)
> scsi_remove_host(scsihost);
> scsi_host_put(scsihost);
>
> - idr_destroy(&devdata->idr);
Do we not have to call xa_destroy()?
> -
> dev_set_drvdata(&dev->device, NULL);
> debugfs_remove(devdata->debugfs_info);
> debugfs_remove_recursive(devdata->debugfs_dir);
regards,
dan carpenter
On Tue, May 04, 2021 at 02:00:01PM +0300, Dan Carpenter wrote:
> On Tue, May 04, 2021 at 12:07:44PM +0200, Fabio M. De Francesco wrote:
> > -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 == 0)
> > + cmdrsp->scsitaskmgmt.notify_handle = id;
> > + else
> > + return ret;
>
> Reverse the condition. Always do error handling, not success handling.
> Try keep the success path at one tab indent and the failure path at two
> tab indents.
>
> 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(xa, cmdrsp->scsitaskmgmt.notify_handle);
umm. When you put these things right next to each other, it's obvious
that should be xa_erase_irq().
> > -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(xa, cmdrsp->scsitaskmgmt.notify_handle);
> > + xa_erase(xa, cmdrsp->scsitaskmgmt.notifyresult_handle);
If this code were even run, assuming the appropriate lockdep options
were enabled, xarray would point out that you were taking a lock with
interrupts enabled that was previously taken with interrupts disabled.
That's a good thing! Because before, this code was deleting entries
from the IDR with _no_ locking.
So these should both be xa_erase_irq().
> > @@ -1096,8 +1085,6 @@ static void visorhba_remove(struct visor_device *dev)
> > scsi_remove_host(scsihost);
> > scsi_host_put(scsihost);
> >
> > - idr_destroy(&devdata->idr);
>
> Do we not have to call xa_destroy()?
Correct. We covered this in earlier iterations of this series and I
don't feel like typing out the explanation again.