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Message-ID: <565814E8.9020408@bjorling.me>
Date: Fri, 27 Nov 2015 09:31:36 +0100
From: Matias Bjørling <m@...rling.me>
To: Wenwei Tao <ww.tao0320@...il.com>, keith.busch@...el.com,
axboe@...com
CC: linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-nvme@...ts.infradead.org
Subject: Re: [PATCH v2 1/3] lightnvm: missing nvm_lock acquire
On 11/27/2015 05:09 AM, Wenwei Tao wrote:
> To avoid race conditions, traverse dev, media manager,
> and targeet lists and also register, unregister entries
> to/from them, should be always under the nvm_lock control.
>
> Signed-off-by: Wenwei Tao <ww.tao0320@...il.com>
> ---
> drivers/lightnvm/core.c | 73 +++++++++++++++++++++++++------------------------
> 1 file changed, 38 insertions(+), 35 deletions(-)
>
> diff --git a/drivers/lightnvm/core.c b/drivers/lightnvm/core.c
> index 5178645..071a3e4 100644
> --- a/drivers/lightnvm/core.c
> +++ b/drivers/lightnvm/core.c
> @@ -123,6 +123,24 @@ void nvm_unregister_mgr(struct nvmm_type *mt)
> }
> EXPORT_SYMBOL(nvm_unregister_mgr);
>
> +/* register with device with a supported manager */
> +static int register_mgr(struct nvm_dev *dev)
> +{
> + struct nvmm_type *mt;
> + int ret = 0;
> +
> + list_for_each_entry(mt, &nvm_mgrs, list) {
> + ret = mt->register_mgr(dev);
> + if (ret > 0) {
> + dev->mt = mt;
> + break; /* successfully initialized */
> + }
> + }
> + if (!ret)
> + pr_info("nvm: no compatible nvm manager found.\n");
> + return ret;
> +}
> +
> static struct nvm_dev *nvm_find_nvm_dev(const char *name)
> {
> struct nvm_dev *dev;
> @@ -221,7 +239,6 @@ static void nvm_free(struct nvm_dev *dev)
>
> static int nvm_init(struct nvm_dev *dev)
> {
> - struct nvmm_type *mt;
> int ret = -EINVAL;
>
> if (!dev->q || !dev->ops)
> @@ -251,22 +268,13 @@ static int nvm_init(struct nvm_dev *dev)
> pr_err("nvm: could not initialize core structures.\n");
> goto err;
> }
> -
> - /* register with device with a supported manager */
> - list_for_each_entry(mt, &nvm_mgrs, list) {
> - ret = mt->register_mgr(dev);
> - if (ret < 0)
> - goto err; /* initialization failed */
> - if (ret > 0) {
> - dev->mt = mt;
> - break; /* successfully initialized */
> - }
> - }
> -
> - if (!ret) {
> - pr_info("nvm: no compatible manager found.\n");
> + down_write(&nvm_lock);
> + ret = register_mgr(dev);
> + up_write(&nvm_lock);
> + if (ret < 0)
> + goto err;
> + if (!ret)
> return 0;
> - }
>
> pr_info("nvm: registered %s [%u/%u/%u/%u/%u/%u]\n",
> dev->name, dev->sec_per_pg, dev->nr_planes,
> @@ -335,18 +343,18 @@ EXPORT_SYMBOL(nvm_register);
>
> void nvm_unregister(char *disk_name)
> {
> + down_write(&nvm_lock);
> struct nvm_dev *dev = nvm_find_nvm_dev(disk_name);
>
> if (!dev) {
> pr_err("nvm: could not find device %s to unregister\n",
> disk_name);
> + up_write(&nvm_lock);
> return;
> }
>
> - down_write(&nvm_lock);
> list_del(&dev->devices);
> up_write(&nvm_lock);
> -
> nvm_exit(dev);
> kfree(dev);
> }
> @@ -361,38 +369,30 @@ static int nvm_create_target(struct nvm_dev *dev,
> {
> struct nvm_ioctl_create_simple *s = &create->conf.s;
> struct request_queue *tqueue;
> - struct nvmm_type *mt;
> struct gendisk *tdisk;
> struct nvm_tgt_type *tt;
> struct nvm_target *t;
> void *targetdata;
> int ret = 0;
>
> + down_write(&nvm_lock);
> if (!dev->mt) {
> - /* register with device with a supported NVM manager */
> - list_for_each_entry(mt, &nvm_mgrs, list) {
> - ret = mt->register_mgr(dev);
> - if (ret < 0)
> - return ret; /* initialization failed */
> - if (ret > 0) {
> - dev->mt = mt;
> - break; /* successfully initialized */
> - }
> - }
> -
> - if (!ret) {
> - pr_info("nvm: no compatible nvm manager found.\n");
> - return -ENODEV;
> + ret = register_mgr(dev);
> + if (!ret)
> + ret = -ENODEV;
> + if (ret < 0) {
> + up_write(&nvm_lock);
> + return ret;
> }
> }
>
> tt = nvm_find_target_type(create->tgttype);
> if (!tt) {
> pr_err("nvm: target type %s not found\n", create->tgttype);
> + up_write(&nvm_lock);
> return -EINVAL;
> }
>
> - down_write(&nvm_lock);
> list_for_each_entry(t, &dev->online_targets, list) {
> if (!strcmp(create->tgtname, t->disk->disk_name)) {
> pr_err("nvm: target name already exists.\n");
> @@ -475,8 +475,9 @@ static int __nvm_configure_create(struct nvm_ioctl_create *create)
> {
> struct nvm_dev *dev;
> struct nvm_ioctl_create_simple *s;
> -
> + down_write(&nvm_lock);
> dev = nvm_find_nvm_dev(create->dev);
> + up_write(&nvm_lock);
> if (!dev) {
> pr_err("nvm: device not found\n");
> return -EINVAL;
> @@ -535,7 +536,9 @@ static int nvm_configure_show(const char *val)
> return -EINVAL;
> }
>
> + down_write(&nvm_lock);
> dev = nvm_find_nvm_dev(devname);
> + up_write(&nvm_lock);
> if (!dev) {
> pr_err("nvm: device not found\n");
> return -EINVAL;
>
Thanks Wei. I applied the previous version of the patch.
You can see the patches I have queued for upstream in the for-next at
https://github.com/OpenChannelSSD/linux/commits/for-next
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