On Monday, April 26, 2021 9:21:01 PM CEST Matthew Wilcox wrote:
> On Mon, Apr 26, 2021 at 08:42:45PM +0200, Fabio M. De Francesco wrote:
> > +static void 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);
> > + u32 id;
> > + int ret;
> > +
> > + /* specify the event that has to be triggered when this cmd is
complete */
> > + id = (u32)cmdrsp->scsitaskmgmt.notify_handle;
> > + ret = xa_alloc_irq(xa, &id, event, XA_LIMIT(1, INT_MAX),
GFP_KERNEL);
>
> OK, think this one through a bit. When xa_alloc_irq() stores the ID that
> it assigned into 'id', what happens to it next?
>
Oh, I overlooked that... The ID in 'id' is lost when the function exits and
the stack frame is unwound.
Now I have another problem: xa_alloc_irq() writes id u32* but I have an u64*
in 'id'. What happens if I cast 'id' to an u32* when passing it to
xa_alloc_irq()?
u64 *id;
int ret;
id = &cmdrsp->scsitaskmgmt.notify_handle;
ret = xa_alloc_irq(xa, (u32 *)id, event, XA_LIMIT(1, INT_MAX), GFP_KERNEL);
Do I destroy the information stored in 'id' with that cast?
>
> > + id = (u32)cmdrsp->scsitaskmgmt.notifyresult_handle;
> > + ret = xa_alloc_irq(xa, &id, result, XA_LIMIT(1, INT_MAX),
GFP_KERNEL);
> >
> > }
> >
> > @@ -1053,8 +1018,6 @@ static int visorhba_probe(struct visor_device *dev)
> >
> > if (err)
> >
> > goto err_debugfs_info;
> >
> > - idr_init(&devdata->idr);
>
> You still need to initialise the XArray, either with xa_init() or by
> using DEFINE_XARRAY. Since it's dynamically allocated, the former is
> correct.
>
I had read that XArray must be initialized with xa_init(). However, when I
deleted the line with the initialization of the IDR, I forgot to replace it
with a statement that uses xa_init().
Thanks,
Fabio
