On Sat, May 24, 2014 at 03:06:09PM -0400, Dan Streetman wrote:
> Add try_module_get() to pool creation functions for zbud and zsmalloc,
> and module_put() to pool destruction functions, since they now can be
> modules used via zpool. Without usage counting, they could be unloaded
> while pool(s) were active, resulting in an oops.
I like the idea here, but what about doing this in the zpool layer? For
me, it is kinda weird for a module to be taking a ref on itself. Maybe
this is excepted practice. Is there precedent for this?
What about having the zbud/zsmalloc drivers pass their module pointers
to zpool_register_driver() as an additional field in struct zpool_driver
and have zpool take the reference? Since zpool is the one in trouble if
the driver is unloaded.
Seth
>
> Signed-off-by: Dan Streetman <ddstreet@xxxxxxxx>
> Cc: Seth Jennings <sjennings@xxxxxxxxxxxxxx>
> Cc: Minchan Kim <minchan@xxxxxxxxxx>
> Cc: Nitin Gupta <ngupta@xxxxxxxxxx>
> Cc: Weijie Yang <weijie.yang@xxxxxxxxxxx>
> ---
>
> New for this patch set.
>
> mm/zbud.c | 5 +++++
> mm/zsmalloc.c | 5 +++++
> 2 files changed, 10 insertions(+)
>
> diff --git a/mm/zbud.c b/mm/zbud.c
> index 8a72cb1..2b3689c 100644
> --- a/mm/zbud.c
> +++ b/mm/zbud.c
> @@ -282,6 +282,10 @@ struct zbud_pool *zbud_create_pool(gfp_t gfp, struct zbud_ops *ops)
> pool = kmalloc(sizeof(struct zbud_pool), GFP_KERNEL);
> if (!pool)
> return NULL;
> + if (!try_module_get(THIS_MODULE)) {
> + kfree(pool);
> + return NULL;
> + }
> spin_lock_init(&pool->lock);
> for_each_unbuddied_list(i, 0)
> INIT_LIST_HEAD(&pool->unbuddied[i]);
> @@ -302,6 +306,7 @@ struct zbud_pool *zbud_create_pool(gfp_t gfp, struct zbud_ops *ops)
> void zbud_destroy_pool(struct zbud_pool *pool)
> {
> kfree(pool);
> + module_put(THIS_MODULE);
> }
>
> /**
> diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
> index 07c3130..2cc2647 100644
> --- a/mm/zsmalloc.c
> +++ b/mm/zsmalloc.c
> @@ -946,6 +946,10 @@ struct zs_pool *zs_create_pool(gfp_t flags)
> pool = kzalloc(ovhd_size, GFP_KERNEL);
> if (!pool)
> return NULL;
> + if (!try_module_get(THIS_MODULE)) {
> + kfree(pool);
> + return NULL;
> + }
>
> for (i = 0; i < ZS_SIZE_CLASSES; i++) {
> int size;
> @@ -985,6 +989,7 @@ void zs_destroy_pool(struct zs_pool *pool)
> }
> }
> kfree(pool);
> + module_put(THIS_MODULE);
> }
> EXPORT_SYMBOL_GPL(zs_destroy_pool);
>
> --
> 1.8.3.1
>
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