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Message-ID: <CACygaLAW23EbxN2Sw33K3Zzyq1P=mM4ouUq6SSxV=_2A0HJJjg@mail.gmail.com>
Date: Fri, 27 Nov 2015 20:04:00 +0800
From: Wenwei Tao <ww.tao0320@...il.com>
To: Matias Bjørling <m@...rling.me>
Cc: keith.busch@...el.com, axboe@...com, 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
Hi Matias
Previous version patch miss acquire lock before find supported manager
in nvm_init().
And find supported manager code is duplicated in nvm_init() and
nvm_create_target(), we may move it into a function to make the code
more clean.
And find supported manager may blocked while holding the lock, this is
not good.
2015-11-27 16:31 GMT+08:00 Matias Bjørling <m@...rling.me>:
> 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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