From: Alex Williamson <alex.williamson@redhat.com>
To: Yi Liu <yi.l.liu@intel.com>
Cc: jgg@nvidia.com, kevin.tian@intel.com, joro@8bytes.org,
robin.murphy@arm.com, eric.auger@redhat.com, nicolinc@nvidia.com,
kvm@vger.kernel.org, chao.p.peng@linux.intel.com,
iommu@lists.linux.dev, baolu.lu@linux.intel.com,
zhenzhong.duan@intel.com, jacob.jun.pan@intel.com,
Matthew Wilcox <willy@infradead.org>
Subject: Re: [PATCH v2 1/4] ida: Add ida_get_lowest()
Date: Tue, 16 Apr 2024 10:03:29 -0600 [thread overview]
Message-ID: <20240416100329.35cede17.alex.williamson@redhat.com> (raw)
In-Reply-To: <20240412082121.33382-2-yi.l.liu@intel.com>
On Fri, 12 Apr 2024 01:21:18 -0700
Yi Liu <yi.l.liu@intel.com> wrote:
> There is no helpers for user to check if a given ID is allocated or not,
> neither a helper to loop all the allocated IDs in an IDA and do something
> for cleanup. With the two needs, a helper to get the lowest allocated ID
> of a range can help to achieve it.
>
> Caller can check if a given ID is allocated or not by:
> int id = 200, rc;
>
> rc = ida_get_lowest(&ida, id, id);
> if (rc == id)
> //id 200 is used
> else
> //id 200 is not used
>
> Caller can iterate all allocated IDs by:
> int id = 0;
>
> while (!ida_is_empty(&pasid_ida)) {
> id = ida_get_lowest(pasid_ida, id, INT_MAX);
> if (id < 0)
> break;
> //anything to do with the allocated ID
> ida_free(pasid_ida, pasid);
> }
>
> Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
> Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
> Signed-off-by: Yi Liu <yi.l.liu@intel.com>
> ---
> include/linux/idr.h | 1 +
> lib/idr.c | 67 +++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 68 insertions(+)
>
> diff --git a/include/linux/idr.h b/include/linux/idr.h
> index da5f5fa4a3a6..1dae71d4a75d 100644
> --- a/include/linux/idr.h
> +++ b/include/linux/idr.h
> @@ -257,6 +257,7 @@ struct ida {
> int ida_alloc_range(struct ida *, unsigned int min, unsigned int max, gfp_t);
> void ida_free(struct ida *, unsigned int id);
> void ida_destroy(struct ida *ida);
> +int ida_get_lowest(struct ida *ida, unsigned int min, unsigned int max);
>
> /**
> * ida_alloc() - Allocate an unused ID.
> diff --git a/lib/idr.c b/lib/idr.c
> index da36054c3ca0..03e461242fe2 100644
> --- a/lib/idr.c
> +++ b/lib/idr.c
> @@ -476,6 +476,73 @@ int ida_alloc_range(struct ida *ida, unsigned int min, unsigned int max,
> }
> EXPORT_SYMBOL(ida_alloc_range);
>
> +/**
> + * ida_get_lowest - Get the lowest used ID.
> + * @ida: IDA handle.
> + * @min: Lowest ID to get.
> + * @max: Highest ID to get.
> + *
> + * Get the lowest used ID between @min and @max, inclusive. The returned
> + * ID will not exceed %INT_MAX, even if @max is larger.
> + *
> + * Context: Any context. Takes and releases the xa_lock.
> + * Return: The lowest used ID, or errno if no used ID is found.
> + */
> +int ida_get_lowest(struct ida *ida, unsigned int min, unsigned int max)
> +{
> + unsigned long index = min / IDA_BITMAP_BITS;
> + unsigned int offset = min % IDA_BITMAP_BITS;
> + unsigned long *addr, size, bit;
> + unsigned long flags;
> + void *entry;
> + int ret;
> +
> + if (min >= INT_MAX)
> + return -EINVAL;
> + if (max >= INT_MAX)
> + max = INT_MAX;
> +
Could these be made consistent with the test in ida_alloc_range(), ie:
if ((int)min < 0)
return -EINVAL;
if ((int)max < 0)
max = INT_MAX;
> + xa_lock_irqsave(&ida->xa, flags);
> +
> + entry = xa_find(&ida->xa, &index, max / IDA_BITMAP_BITS, XA_PRESENT);
> + if (!entry) {
> + ret = -ENOTTY;
-ENOENT? Same for all below too.
> + goto err_unlock;
> + }
> +
> + if (index > min / IDA_BITMAP_BITS)
> + offset = 0;
> + if (index * IDA_BITMAP_BITS + offset > max) {
> + ret = -ENOTTY;
> + goto err_unlock;
> + }
> +
> + if (xa_is_value(entry)) {
> + unsigned long tmp = xa_to_value(entry);
> +
> + addr = &tmp;
> + size = BITS_PER_XA_VALUE;
> + } else {
> + addr = ((struct ida_bitmap *)entry)->bitmap;
> + size = IDA_BITMAP_BITS;
> + }
> +
> + bit = find_next_bit(addr, size, offset);
> +
> + xa_unlock_irqrestore(&ida->xa, flags);
> +
> + if (bit == size ||
> + index * IDA_BITMAP_BITS + bit > max)
> + return -ENOTTY;
> +
> + return index * IDA_BITMAP_BITS + bit;
> +
> +err_unlock:
> + xa_unlock_irqrestore(&ida->xa, flags);
> + return ret;
> +}
> +EXPORT_SYMBOL(ida_get_lowest);
The API is a bit awkward to me, I wonder if it might be helped with
some renaming and wrappers...
int ida_find_first_range(struct ida *ida, unsigned int min, unsigned int max);
bool ida_exists(struct ida *ida, unsigned int id)
{
return ida_find_first_range(ida, id, id) == id;
}
int ida_find_first(struct ida *ida)
{
return ida_find_first_range(ida, 0, ~0);
}
_min and _max variations of the latter would align with existing
ida_alloc variants, but maybe no need to add them preemptively.
Possibly an ida_for_each() could be useful in the use case of
disassociating each id, but not required for the brute force iterative
method. Thanks,
Alex
> +
> /**
> * ida_free() - Release an allocated ID.
> * @ida: IDA handle.
next prev parent reply other threads:[~2024-04-16 16:03 UTC|newest]
Thread overview: 72+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-12 8:21 [PATCH v2 0/4] vfio-pci support pasid attach/detach Yi Liu
2024-04-12 8:21 ` [PATCH v2 1/4] ida: Add ida_get_lowest() Yi Liu
2024-04-16 16:03 ` Alex Williamson [this message]
2024-04-18 7:02 ` Yi Liu
2024-04-18 16:23 ` Alex Williamson
2024-04-18 17:12 ` Jason Gunthorpe
2024-04-19 13:43 ` Yi Liu
2024-04-19 13:55 ` Alex Williamson
2024-04-19 14:00 ` Jason Gunthorpe
2024-04-23 7:19 ` Yi Liu
2024-04-19 13:40 ` Yi Liu
2024-04-12 8:21 ` [PATCH v2 2/4] vfio-iommufd: Support pasid [at|de]tach for physical VFIO devices Yi Liu
2024-04-16 9:01 ` Tian, Kevin
2024-04-16 9:24 ` Yi Liu
2024-04-16 9:47 ` Tian, Kevin
2024-04-18 7:04 ` Yi Liu
2024-04-23 12:43 ` Jason Gunthorpe
2024-04-24 0:33 ` Tian, Kevin
2024-04-24 4:48 ` Yi Liu
2024-04-12 8:21 ` [PATCH v2 3/4] vfio: Add VFIO_DEVICE_PASID_[AT|DE]TACH_IOMMUFD_PT Yi Liu
2024-04-16 9:13 ` Tian, Kevin
2024-04-16 9:36 ` Yi Liu
2024-04-23 12:45 ` Jason Gunthorpe
2024-04-12 8:21 ` [PATCH v2 4/4] vfio: Report PASID capability via VFIO_DEVICE_FEATURE ioctl Yi Liu
2024-04-16 9:40 ` Tian, Kevin
2024-04-16 17:57 ` Alex Williamson
2024-04-17 7:09 ` Tian, Kevin
2024-04-17 20:25 ` Alex Williamson
2024-04-18 0:21 ` Tian, Kevin
2024-04-18 8:23 ` Yi Liu
2024-04-18 16:34 ` Alex Williamson
2024-04-23 12:39 ` Jason Gunthorpe
2024-04-24 0:24 ` Tian, Kevin
2024-04-24 13:59 ` Jason Gunthorpe
2024-04-16 8:38 ` [PATCH v2 0/4] vfio-pci support pasid attach/detach Tian, Kevin
2024-04-16 17:50 ` Jason Gunthorpe
2024-04-17 7:16 ` Tian, Kevin
2024-04-17 12:20 ` Jason Gunthorpe
2024-04-17 23:02 ` Alex Williamson
2024-04-18 0:06 ` Tian, Kevin
2024-04-18 9:03 ` Yi Liu
2024-04-18 20:37 ` Alex Williamson
2024-04-19 5:52 ` Tian, Kevin
2024-04-19 16:35 ` Alex Williamson
2024-04-23 7:43 ` Tian, Kevin
2024-04-23 12:01 ` Jason Gunthorpe
2024-04-23 23:47 ` Tian, Kevin
2024-04-24 0:12 ` Jason Gunthorpe
2024-04-24 2:57 ` Tian, Kevin
2024-04-24 12:29 ` Baolu Lu
2024-04-24 14:04 ` Jason Gunthorpe
2024-04-24 5:19 ` Tian, Kevin
2024-04-24 14:15 ` Jason Gunthorpe
2024-04-24 18:38 ` Alex Williamson
2024-04-24 18:45 ` Jason Gunthorpe
2024-04-24 18:24 ` Alex Williamson
2024-04-24 18:36 ` Jason Gunthorpe
2024-04-24 20:13 ` Alex Williamson
2024-04-26 14:11 ` Jason Gunthorpe
2024-04-26 20:13 ` Alex Williamson
2024-04-28 6:19 ` Tian, Kevin
2024-04-29 7:43 ` Yi Liu
2024-04-29 17:15 ` Jason Gunthorpe
2024-04-29 17:44 ` Jason Gunthorpe
2024-04-27 5:05 ` Christoph Hellwig
2024-04-25 9:26 ` Yi Liu
2024-04-25 12:58 ` Alex Williamson
2024-04-26 9:01 ` Yi Liu
2024-04-19 13:59 ` Jason Gunthorpe
2024-04-23 7:58 ` Yi Liu
2024-04-23 12:05 ` Jason Gunthorpe
2024-04-19 13:34 ` Jason Gunthorpe
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