2024-03-07 10:08:35

by Kory Maincent

[permalink] [raw]
Subject: [PATCH net-next] ptp: Move from simple ida to xarray

Move from simple ida to xarray for storing and loading the ptp_clock
pointer. This prepares support for future hardware timestamp selection by
being able to link the ptp clock index to its pointer.

Signed-off-by: Kory Maincent <[email protected]>
---
---
drivers/ptp/ptp_clock.c | 15 +++++++--------
1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/drivers/ptp/ptp_clock.c b/drivers/ptp/ptp_clock.c
index 3aaf1a3430c5..392c880d9f34 100644
--- a/drivers/ptp/ptp_clock.c
+++ b/drivers/ptp/ptp_clock.c
@@ -31,7 +31,7 @@ struct class *ptp_class;

static dev_t ptp_devt;

-static DEFINE_IDA(ptp_clocks_map);
+static DEFINE_XARRAY_ALLOC(ptp_clocks_map);

/* time stamp event queue operations */

@@ -201,7 +201,7 @@ static void ptp_clock_release(struct device *dev)
bitmap_free(tsevq->mask);
kfree(tsevq);
debugfs_remove(ptp->debugfs_root);
- ida_free(&ptp_clocks_map, ptp->index);
+ xa_erase(&ptp_clocks_map, ptp->index);
kfree(ptp);
}

@@ -246,11 +246,10 @@ struct ptp_clock *ptp_clock_register(struct ptp_clock_info *info,
if (ptp == NULL)
goto no_memory;

- index = ida_alloc_max(&ptp_clocks_map, MINORMASK, GFP_KERNEL);
- if (index < 0) {
- err = index;
+ err = xa_alloc(&ptp_clocks_map, &index, ptp, xa_limit_31b,
+ GFP_KERNEL);
+ if (err)
goto no_slot;
- }

ptp->clock.ops = ptp_clock_ops;
ptp->info = info;
@@ -378,7 +377,7 @@ struct ptp_clock *ptp_clock_register(struct ptp_clock_info *info,
list_del(&queue->qlist);
kfree(queue);
no_memory_queue:
- ida_free(&ptp_clocks_map, index);
+ xa_erase(&ptp_clocks_map, index);
no_slot:
kfree(ptp);
no_memory:
@@ -511,7 +510,7 @@ static void __exit ptp_exit(void)
{
class_destroy(ptp_class);
unregister_chrdev_region(ptp_devt, MINORMASK + 1);
- ida_destroy(&ptp_clocks_map);
+ xa_destroy(&ptp_clocks_map);
}

static int __init ptp_init(void)
--
2.25.1



2024-03-08 21:07:58

by Simon Horman

[permalink] [raw]
Subject: Re: [PATCH net-next] ptp: Move from simple ida to xarray

On Thu, Mar 07, 2024 at 11:03:26AM +0100, Kory Maincent wrote:
> Move from simple ida to xarray for storing and loading the ptp_clock
> pointer. This prepares support for future hardware timestamp selection by
> being able to link the ptp clock index to its pointer.
>
> Signed-off-by: Kory Maincent <[email protected]>

..

> @@ -246,11 +246,10 @@ struct ptp_clock *ptp_clock_register(struct ptp_clock_info *info,
> if (ptp == NULL)
> goto no_memory;
>
> - index = ida_alloc_max(&ptp_clocks_map, MINORMASK, GFP_KERNEL);
> - if (index < 0) {
> - err = index;
> + err = xa_alloc(&ptp_clocks_map, &index, ptp, xa_limit_31b,
> + GFP_KERNEL);
> + if (err)
> goto no_slot;
> - }
>
> ptp->clock.ops = ptp_clock_ops;
> ptp->info = info;

Hi Kory,

Prior to this change err was -ENOMEM at this point. Now it is 0.

And The immediately following code is:

ptp->devid = MKDEV(major, index);
ptp->index = index;
INIT_LIST_HEAD(&ptp->tsevqs);
queue = kzalloc(sizeof(*queue), GFP_KERNEL);
if (!queue)
goto no_memory_queue;

The goto above results in:

return ERR_PTR(err);

But here err is 0. This does not seem correct.

Flagged by Smatch.

..

--
pw-bot: changes-requested

2024-03-11 09:09:27

by Kory Maincent

[permalink] [raw]
Subject: Re: [PATCH net-next] ptp: Move from simple ida to xarray

On Fri, 8 Mar 2024 21:07:45 +0000
Simon Horman <[email protected]> wrote:

> On Thu, Mar 07, 2024 at 11:03:26AM +0100, Kory Maincent wrote:
> > Move from simple ida to xarray for storing and loading the ptp_clock
> > pointer. This prepares support for future hardware timestamp selection by
> > being able to link the ptp clock index to its pointer.
> >
> > Signed-off-by: Kory Maincent <[email protected]>
>
> ...
>
> > @@ -246,11 +246,10 @@ struct ptp_clock *ptp_clock_register(struct
> > ptp_clock_info *info, if (ptp == NULL)
> > goto no_memory;
> >
> > - index = ida_alloc_max(&ptp_clocks_map, MINORMASK, GFP_KERNEL);
> > - if (index < 0) {
> > - err = index;
> > + err = xa_alloc(&ptp_clocks_map, &index, ptp, xa_limit_31b,
> > + GFP_KERNEL);
> > + if (err)
> > goto no_slot;
> > - }
> >
> > ptp->clock.ops = ptp_clock_ops;
> > ptp->info = info;
>
> Hi Kory,
>
> Prior to this change err was -ENOMEM at this point. Now it is 0.

You are totally right. Thanks for reporting the issue!

Regards,
--
Köry Maincent, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com