Messages in this thread | | | Date | Thu, 23 Apr 2015 11:23:58 +0900 | From | Minchan Kim <> | Subject | Re: [PATCHv2 03/10] zram: use idr instead of `zram_devices' array |
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On Thu, Apr 16, 2015 at 08:55:49PM +0900, Sergey Senozhatsky wrote: > This patch makes some preparations for on-demand device add/remove > functionality. > > Remove `zram_devices' array and switch to id-to-pointer translation (idr). > idr doesn't bloat zram struct with additional members, f.e. list_head, > yet still provides ability to match the device_id with the device pointer. > > No user-space visible changes. > > [do not lose -ENOMEM return code when `queue' allocation has failed] > Reported-by: Julia Lawall <Julia.Lawall@lip6.fr> > Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> > --- > drivers/block/zram/zram_drv.c | 86 ++++++++++++++++++++++++------------------- > 1 file changed, 49 insertions(+), 37 deletions(-) > > diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c > index 14043b2..4511830 100644 > --- a/drivers/block/zram/zram_drv.c > +++ b/drivers/block/zram/zram_drv.c > @@ -32,12 +32,12 @@ > #include <linux/string.h> > #include <linux/vmalloc.h> > #include <linux/err.h> > +#include <linux/idr.h> > > #include "zram_drv.h" > > -/* Globals */ > +static DEFINE_IDR(zram_index_idr); > static int zram_major; > -static struct zram *zram_devices; > static const char *default_compressor = "lzo"; > > /* Module params (documentation at end) */ > @@ -1156,10 +1156,20 @@ static struct attribute_group zram_disk_attr_group = { > .attrs = zram_disk_attrs, > }; > > -static int create_device(struct zram *zram, int device_id) > +static int zram_add(int device_id) > { > + struct zram *zram; > struct request_queue *queue; > - int ret = -ENOMEM; > + int ret; > + > + zram = kzalloc(sizeof(struct zram), GFP_KERNEL); > + if (!zram) > + return -ENOMEM; > + > + ret = idr_alloc(&zram_index_idr, zram, device_id, > + device_id + 1, GFP_KERNEL); > + if (ret < 0) > + goto out_free_dev; > > init_rwsem(&zram->init_lock); > > @@ -1167,12 +1177,13 @@ static int create_device(struct zram *zram, int device_id) > if (!queue) { > pr_err("Error allocating disk queue for device %d\n", > device_id); > - goto out; > + ret = -ENOMEM; > + goto out_free_idr; > } > > blk_queue_make_request(queue, zram_make_request); > > - /* gendisk structure */ > + /* gendisk structure */ > zram->disk = alloc_disk(1); > if (!zram->disk) { > pr_warn("Error allocating disk structure for device %d\n", > @@ -1237,34 +1248,42 @@ out_free_disk: > put_disk(zram->disk); > out_free_queue: > blk_cleanup_queue(queue); > -out: > +out_free_idr: > + idr_remove(&zram_index_idr, device_id); > +out_free_dev: > + kfree(zram); > return ret; > } > > -static void destroy_devices(unsigned int nr) > +static void zram_remove(struct zram *zram) > { > - struct zram *zram; > - unsigned int i; > - > - for (i = 0; i < nr; i++) { > - zram = &zram_devices[i]; > - /* > - * Remove sysfs first, so no one will perform a disksize > - * store while we destroy the devices > - */ > - sysfs_remove_group(&disk_to_dev(zram->disk)->kobj, > - &zram_disk_attr_group); > + /* > + * Remove sysfs first, so no one will perform a disksize > + * store while we destroy the devices > + */ > + sysfs_remove_group(&disk_to_dev(zram->disk)->kobj, > + &zram_disk_attr_group); > > - zram_reset_device(zram); > + zram_reset_device(zram); > + idr_remove(&zram_index_idr, zram->disk->first_minor); > + blk_cleanup_queue(zram->disk->queue); > + del_gendisk(zram->disk); > + put_disk(zram->disk); > + kfree(zram); > +} > > - blk_cleanup_queue(zram->disk->queue); > - del_gendisk(zram->disk); > - put_disk(zram->disk); > - } > +static int zram_exit_cb(int id, void *ptr, void *data)
trivial: I prefer remove to exit.
> +{ > + zram_remove(ptr); > + return 0; > +} > > - kfree(zram_devices); > +static void destroy_devices(void) > +{ > + idr_for_each(&zram_index_idr, &zram_exit_cb, NULL); > + idr_destroy(&zram_index_idr); > unregister_blkdev(zram_major, "zram"); > - pr_info("Destroyed %u device(s)\n", nr); > + pr_info("Destroyed device(s)\n"); > } > > static int __init zram_init(void) > @@ -1283,16 +1302,9 @@ static int __init zram_init(void) > return -EBUSY; > } > > - /* Allocate the device array and initialize each one */ > - zram_devices = kzalloc(num_devices * sizeof(struct zram), GFP_KERNEL); > - if (!zram_devices) { > - unregister_blkdev(zram_major, "zram"); > - return -ENOMEM; > - } > - > for (dev_id = 0; dev_id < num_devices; dev_id++) { > - ret = create_device(&zram_devices[dev_id], dev_id); > - if (ret) > + ret = zram_add(dev_id); > + if (ret != 0)
It's better to check ret < 0 rather than ret != 0.
Otherwise, Acked-by: Minchan Kim <minchan@kernel.org>
-- Kind regards, Minchan Kim
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