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Message-ID: <6041982e-3c65-497f-b7bf-3ac444fa3623@oracle.com>
Date: Tue, 6 Feb 2024 11:01:16 +0000
From: John Garry <john.g.garry@...cle.com>
To: Robin Murphy <robin.murphy@....com>, joro@...tes.org
Cc: will@...nel.org, pasha.tatashin@...een.com, iommu@...ts.linux.dev,
linux-kernel@...r.kernel.org, linux-mm@...ck.org, rientjes@...gle.com,
yosryahmed@...gle.com
Subject: Re: [PATCH v3 1/3] iommu/iova: Tidy up iova_cache_get() failure
On 05/02/2024 15:32, Robin Murphy wrote:
> Failure handling in iova_cache_get() is a little messy, and we'd like
> to add some more to it, so let's tidy up a bit first. By leaving the
> hotplug handler until last we can take advantage of kmem_cache_destroy()
> being NULL-safe to have a single cleanup label. We can also improve the
> error reporting, noting that kmem_cache_create() already screams if it
> fails, so that one is redundant.
>
> Signed-off-by: Robin Murphy <robin.murphy@....com>
Regardless of a couple of minor comments, below, FWIW:
Reviewed-by: John Garry <john.g.garry@...cle.com>
> ---
> drivers/iommu/iova.c | 33 ++++++++++++++++-----------------
> 1 file changed, 16 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c
> index d30e453d0fb4..cf95001d85c0 100644
> --- a/drivers/iommu/iova.c
> +++ b/drivers/iommu/iova.c
> @@ -254,26 +254,20 @@ static void free_iova_mem(struct iova *iova)
>
> int iova_cache_get(void)
> {
> + int err = -ENOMEM;
> +
> mutex_lock(&iova_cache_mutex);
> if (!iova_cache_users) {
> - int ret;
> + iova_cache = kmem_cache_create("iommu_iova", sizeof(struct iova), 0,
> + SLAB_HWCACHE_ALIGN, NULL);
Maybe can use KMEM_CACHE(), but it would mean that the name would change.
> + if (!iova_cache)
> + goto out_err;
>
> - ret = cpuhp_setup_state_multi(CPUHP_IOMMU_IOVA_DEAD, "iommu/iova:dead", NULL,
> - iova_cpuhp_dead);
> - if (ret) {
> - mutex_unlock(&iova_cache_mutex);
> - pr_err("Couldn't register cpuhp handler\n");
> - return ret;
> - }
> -
> - iova_cache = kmem_cache_create(
> - "iommu_iova", sizeof(struct iova), 0,
> - SLAB_HWCACHE_ALIGN, NULL);
> - if (!iova_cache) {
> - cpuhp_remove_multi_state(CPUHP_IOMMU_IOVA_DEAD);
> - mutex_unlock(&iova_cache_mutex);
> - pr_err("Couldn't create iova cache\n");
> - return -ENOMEM;
> + err = cpuhp_setup_state_multi(CPUHP_IOMMU_IOVA_DEAD, "iommu/iova:dead",
> + NULL, iova_cpuhp_dead);
> + if (err) {
> + pr_err("IOVA: Couldn't register cpuhp handler: %pe\n", ERR_PTR(err));
Maybe can use pr_fmt with "iova".
> + goto out_err;
> }
> }
>
> @@ -281,6 +275,11 @@ int iova_cache_get(void)
> mutex_unlock(&iova_cache_mutex);
>
> return 0;
> +
> +out_err:
> + kmem_cache_destroy(iova_cache);
> + mutex_unlock(&iova_cache_mutex);
> + return err;
> }
> EXPORT_SYMBOL_GPL(iova_cache_get);
>
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