[PATCHv3] tcmu: allow userspace to reset netlink

[PATCHv3] tcmu: allow userspace to reset netlink

[xiubli]

From: Xiubo Li <xiubli@redhat.com>

This patch adds 1 tcmu attr to reset and complete all the blocked
netlink waiting threads. It's used when the userspace daemon like
tcmu-runner has crashed or forced to shutdown just before the
netlink requests be replied to the kernel, then the netlink requeting
threads will get stuck forever. We must reboot the machine to recover
from it and by this the rebootng is not a must then.

The Call Trace will be something like:
=======
INFO: task targetctl:22655 blocked for more than 120 seconds.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
targetctl       D ffff880169718fd0     0 22655  17249 0x00000080
Call Trace:
 [<ffffffff816ab6d9>] schedule+0x29/0x70
 [<ffffffff816a90e9>] schedule_timeout+0x239/0x2c0
 [<ffffffff81574d42>] ? skb_release_data+0xf2/0x140
 [<ffffffff816aba8d>] wait_for_completion+0xfd/0x140
 [<ffffffff810c6440>] ? wake_up_state+0x20/0x20
 [<ffffffffc0159f5a>] tcmu_netlink_event+0x26a/0x3a0 [target_core_user]
 [<ffffffff810b34b0>] ? wake_up_atomic_t+0x30/0x30
 [<ffffffffc015a2c6>] tcmu_configure_device+0x236/0x350 [target_core_user]
 [<ffffffffc05085df>] target_configure_device+0x3f/0x3b0 [target_core_mod]
 [<ffffffffc0502e7c>] target_core_store_dev_enable+0x2c/0x60 [target_core_mod]
 [<ffffffffc0501244>] target_core_dev_store+0x24/0x40 [target_core_mod]
 [<ffffffff8128a0e4>] configfs_write_file+0xc4/0x130
 [<ffffffff81202aed>] vfs_write+0xbd/0x1e0
 [<ffffffff812038ff>] SyS_write+0x7f/0xe0
 [<ffffffff816b89fd>] system_call_fastpath+0x16/0x1b
=======

Signed-off-by: Xiubo Li <xiubli@redhat.com>
---
Changes since v1(suggested by Mike Christie):
v2: - Makes the reset per device.
v3: - Remove nl_cmd->complete, use status instead
    - Fix lock issue 
    - Check if a nl command is even waiting before trying to wake up

 drivers/target/target_core_user.c | 60 +++++++++++++++++++++++++++++++++------
 1 file changed, 51 insertions(+), 9 deletions(-)

diff --git a/drivers/target/target_core_user.c b/drivers/target/target_core_user.c
index 4ad89ea..a831f5b7 100644
--- a/drivers/target/target_core_user.c
+++ b/drivers/target/target_core_user.c
@@ -104,8 +104,8 @@ struct tcmu_hba {
 #define TCMU_CONFIG_LEN 256
 
 struct tcmu_nl_cmd {
-	/* wake up thread waiting for reply */
-	struct completion complete;
+	unsigned int waiter;
+
 	int cmd;
 	int status;
 };
@@ -159,9 +159,12 @@ struct tcmu_dev {
 
 	spinlock_t nl_cmd_lock;
 	struct tcmu_nl_cmd curr_nl_cmd;
-	/* wake up threads waiting on curr_nl_cmd */
+	/* wake up threads waiting on nl_cmd_wq */
 	wait_queue_head_t nl_cmd_wq;
 
+	/* complete thread waiting complete_wq */
+	wait_queue_head_t complete_wq;
+
 	char dev_config[TCMU_CONFIG_LEN];
 
 	int nl_reply_supported;
@@ -307,11 +310,13 @@ static int tcmu_genl_cmd_done(struct genl_info *info, int completed_cmd)
 		nl_cmd->status = rc;
 	}
 
-	spin_unlock(&udev->nl_cmd_lock);
 	if (!is_removed)
 		 target_undepend_item(&dev->dev_group.cg_item);
-	if (!ret)
-		complete(&nl_cmd->complete);
+	if (!ret && nl_cmd->waiter) {
+		nl_cmd->waiter--;
+		wake_up(&udev->complete_wq);
+	}
+	spin_unlock(&udev->nl_cmd_lock);
 	return ret;
 }
 
@@ -1258,6 +1263,7 @@ static struct se_device *tcmu_alloc_device(struct se_hba *hba, const char *name)
 	timer_setup(&udev->cmd_timer, tcmu_cmd_timedout, 0);
 
 	init_waitqueue_head(&udev->nl_cmd_wq);
+	init_waitqueue_head(&udev->complete_wq);
 	spin_lock_init(&udev->nl_cmd_lock);
 
 	INIT_RADIX_TREE(&udev->data_blocks, GFP_KERNEL);
@@ -1554,8 +1560,8 @@ static void tcmu_init_genl_cmd_reply(struct tcmu_dev *udev, int cmd)
 	}
 
 	memset(nl_cmd, 0, sizeof(*nl_cmd));
+	nl_cmd->status = 1;
 	nl_cmd->cmd = cmd;
-	init_completion(&nl_cmd->complete);
 
 	spin_unlock(&udev->nl_cmd_lock);
 }
@@ -1572,13 +1578,16 @@ static int tcmu_wait_genl_cmd_reply(struct tcmu_dev *udev)
 	if (udev->nl_reply_supported <= 0)
 		return 0;
 
+	spin_lock(&udev->nl_cmd_lock);
+	nl_cmd->waiter++;
+	spin_unlock(&udev->nl_cmd_lock);
+
 	pr_debug("sleeping for nl reply\n");
-	wait_for_completion(&nl_cmd->complete);
+	wait_event(udev->complete_wq, nl_cmd->status != 1);
 
 	spin_lock(&udev->nl_cmd_lock);
 	nl_cmd->cmd = TCMU_CMD_UNSPEC;
 	ret = nl_cmd->status;
-	nl_cmd->status = 0;
 	spin_unlock(&udev->nl_cmd_lock);
 
 	wake_up_all(&udev->nl_cmd_wq);
@@ -2323,6 +2332,38 @@ static ssize_t tcmu_block_dev_store(struct config_item *item, const char *page,
 }
 CONFIGFS_ATTR(tcmu_, block_dev);
 
+static ssize_t tcmu_reset_netlink_store(struct config_item *item, const char *page,
+				    size_t count)
+{
+	struct se_device *se_dev = container_of(to_config_group(item),
+						struct se_device,
+						dev_action_group);
+	struct tcmu_dev *udev = TCMU_DEV(se_dev);
+	struct tcmu_nl_cmd *nl_cmd = &udev->curr_nl_cmd;
+	u8 val;
+	int ret;
+
+	ret = kstrtou8(page, 0, &val);
+	if (ret < 0)
+		return ret;
+
+	if (val != 1) {
+		pr_err("Invalid reset value %d\n", val);
+		return -EINVAL;
+	}
+
+	spin_lock(&udev->nl_cmd_lock);
+	if (nl_cmd->waiter) {
+		nl_cmd->waiter--;
+		nl_cmd->status = -EINTR;
+		wake_up(&udev->complete_wq);
+	}
+	spin_unlock(&udev->nl_cmd_lock);
+
+	return count;
+}
+CONFIGFS_ATTR_WO(tcmu_, reset_netlink);
+
 static ssize_t tcmu_reset_ring_store(struct config_item *item, const char *page,
 				     size_t count)
 {
@@ -2363,6 +2404,7 @@ static ssize_t tcmu_reset_ring_store(struct config_item *item, const char *page,
 static struct configfs_attribute *tcmu_action_attrs[] = {
 	&tcmu_attr_block_dev,
 	&tcmu_attr_reset_ring,
+	&tcmu_attr_reset_netlink,
 	NULL,
 };
 
-- 
1.8.3.1

Re: [PATCHv3] tcmu: allow userspace to reset netlink

[Mike Christie]

Nick,

Ignore this v3 too. It will not work for deletion.

On 04/16/2018 07:43 AM, xiubli@redhat.com wrote:
> From: Xiubo Li <xiubli@redhat.com>
> 
> This patch adds 1 tcmu attr to reset and complete all the blocked
> netlink waiting threads. It's used when the userspace daemon like
> tcmu-runner has crashed or forced to shutdown just before the
> netlink requests be replied to the kernel, then the netlink requeting
> threads will get stuck forever. We must reboot the machine to recover
> from it and by this the rebootng is not a must then.
> 
> The Call Trace will be something like:
> =======
> INFO: task targetctl:22655 blocked for more than 120 seconds.
> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> targetctl       D ffff880169718fd0     0 22655  17249 0x00000080
> Call Trace:
>  [<ffffffff816ab6d9>] schedule+0x29/0x70
>  [<ffffffff816a90e9>] schedule_timeout+0x239/0x2c0
>  [<ffffffff81574d42>] ? skb_release_data+0xf2/0x140
>  [<ffffffff816aba8d>] wait_for_completion+0xfd/0x140
>  [<ffffffff810c6440>] ? wake_up_state+0x20/0x20
>  [<ffffffffc0159f5a>] tcmu_netlink_event+0x26a/0x3a0 [target_core_user]
>  [<ffffffff810b34b0>] ? wake_up_atomic_t+0x30/0x30
>  [<ffffffffc015a2c6>] tcmu_configure_device+0x236/0x350 [target_core_user]
>  [<ffffffffc05085df>] target_configure_device+0x3f/0x3b0 [target_core_mod]
>  [<ffffffffc0502e7c>] target_core_store_dev_enable+0x2c/0x60 [target_core_mod]
>  [<ffffffffc0501244>] target_core_dev_store+0x24/0x40 [target_core_mod]
>  [<ffffffff8128a0e4>] configfs_write_file+0xc4/0x130
>  [<ffffffff81202aed>] vfs_write+0xbd/0x1e0
>  [<ffffffff812038ff>] SyS_write+0x7f/0xe0
>  [<ffffffff816b89fd>] system_call_fastpath+0x16/0x1b
> =======
> 
> Signed-off-by: Xiubo Li <xiubli@redhat.com>
> ---
> Changes since v1(suggested by Mike Christie):
> v2: - Makes the reset per device.
> v3: - Remove nl_cmd->complete, use status instead
>     - Fix lock issue 
>     - Check if a nl command is even waiting before trying to wake up
> 
>  drivers/target/target_core_user.c | 60 +++++++++++++++++++++++++++++++++------
>  1 file changed, 51 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/target/target_core_user.c b/drivers/target/target_core_user.c
> index 4ad89ea..a831f5b7 100644
> --- a/drivers/target/target_core_user.c
> +++ b/drivers/target/target_core_user.c
> @@ -104,8 +104,8 @@ struct tcmu_hba {
>  #define TCMU_CONFIG_LEN 256
>  
>  struct tcmu_nl_cmd {
> -	/* wake up thread waiting for reply */
> -	struct completion complete;
> +	unsigned int waiter;
> +
>  	int cmd;
>  	int status;
>  };
> @@ -159,9 +159,12 @@ struct tcmu_dev {
>  
>  	spinlock_t nl_cmd_lock;
>  	struct tcmu_nl_cmd curr_nl_cmd;
> -	/* wake up threads waiting on curr_nl_cmd */
> +	/* wake up threads waiting on nl_cmd_wq */
>  	wait_queue_head_t nl_cmd_wq;
>  
> +	/* complete thread waiting complete_wq */
> +	wait_queue_head_t complete_wq;
> +
>  	char dev_config[TCMU_CONFIG_LEN];
>  
>  	int nl_reply_supported;
> @@ -307,11 +310,13 @@ static int tcmu_genl_cmd_done(struct genl_info *info, int completed_cmd)
>  		nl_cmd->status = rc;
>  	}
>  
> -	spin_unlock(&udev->nl_cmd_lock);
>  	if (!is_removed)
>  		 target_undepend_item(&dev->dev_group.cg_item);
> -	if (!ret)
> -		complete(&nl_cmd->complete);
> +	if (!ret && nl_cmd->waiter) {
> +		nl_cmd->waiter--;
> +		wake_up(&udev->complete_wq);
> +	}
> +	spin_unlock(&udev->nl_cmd_lock);
>  	return ret;
>  }
>  
> @@ -1258,6 +1263,7 @@ static struct se_device *tcmu_alloc_device(struct se_hba *hba, const char *name)
>  	timer_setup(&udev->cmd_timer, tcmu_cmd_timedout, 0);
>  
>  	init_waitqueue_head(&udev->nl_cmd_wq);
> +	init_waitqueue_head(&udev->complete_wq);
>  	spin_lock_init(&udev->nl_cmd_lock);
>  
>  	INIT_RADIX_TREE(&udev->data_blocks, GFP_KERNEL);
> @@ -1554,8 +1560,8 @@ static void tcmu_init_genl_cmd_reply(struct tcmu_dev *udev, int cmd)
>  	}
>  
>  	memset(nl_cmd, 0, sizeof(*nl_cmd));
> +	nl_cmd->status = 1;
>  	nl_cmd->cmd = cmd;
> -	init_completion(&nl_cmd->complete);
>  
>  	spin_unlock(&udev->nl_cmd_lock);
>  }
> @@ -1572,13 +1578,16 @@ static int tcmu_wait_genl_cmd_reply(struct tcmu_dev *udev)
>  	if (udev->nl_reply_supported <= 0)
>  		return 0;
>  
> +	spin_lock(&udev->nl_cmd_lock);
> +	nl_cmd->waiter++;
> +	spin_unlock(&udev->nl_cmd_lock);
> +
>  	pr_debug("sleeping for nl reply\n");
> -	wait_for_completion(&nl_cmd->complete);
> +	wait_event(udev->complete_wq, nl_cmd->status != 1);
>  
>  	spin_lock(&udev->nl_cmd_lock);
>  	nl_cmd->cmd = TCMU_CMD_UNSPEC;
>  	ret = nl_cmd->status;
> -	nl_cmd->status = 0;
>  	spin_unlock(&udev->nl_cmd_lock);
>  
>  	wake_up_all(&udev->nl_cmd_wq);
> @@ -2323,6 +2332,38 @@ static ssize_t tcmu_block_dev_store(struct config_item *item, const char *page,
>  }
>  CONFIGFS_ATTR(tcmu_, block_dev);
>  
> +static ssize_t tcmu_reset_netlink_store(struct config_item *item, const char *page,
> +				    size_t count)
> +{
> +	struct se_device *se_dev = container_of(to_config_group(item),
> +						struct se_device,
> +						dev_action_group);
> +	struct tcmu_dev *udev = TCMU_DEV(se_dev);
> +	struct tcmu_nl_cmd *nl_cmd = &udev->curr_nl_cmd;
> +	u8 val;
> +	int ret;
> +
> +	ret = kstrtou8(page, 0, &val);
> +	if (ret < 0)
> +		return ret;
> +
> +	if (val != 1) {
> +		pr_err("Invalid reset value %d\n", val);
> +		return -EINVAL;
> +	}
> +
> +	spin_lock(&udev->nl_cmd_lock);
> +	if (nl_cmd->waiter) {
> +		nl_cmd->waiter--;
> +		nl_cmd->status = -EINTR;
> +		wake_up(&udev->complete_wq);
> +	}
> +	spin_unlock(&udev->nl_cmd_lock);
> +
> +	return count;
> +}
> +CONFIGFS_ATTR_WO(tcmu_, reset_netlink);
> +
>  static ssize_t tcmu_reset_ring_store(struct config_item *item, const char *page,
>  				     size_t count)
>  {
> @@ -2363,6 +2404,7 @@ static ssize_t tcmu_reset_ring_store(struct config_item *item, const char *page,
>  static struct configfs_attribute *tcmu_action_attrs[] = {
>  	&tcmu_attr_block_dev,
>  	&tcmu_attr_reset_ring,
> +	&tcmu_attr_reset_netlink,
>  	NULL,
>  };
>  
> 

Re: [PATCHv3] tcmu: allow userspace to reset netlink

[Xiubo Li]

On 2018/4/18 0:40, Mike Christie wrote:
> Nick,
>
> Ignore this v3 too. It will not work for deletion.
Yeah, for deletion the vfs will lock the file, so there is no any new 
access could in, will redesign and make it module wide.

> On 04/16/2018 07:43 AM, xiubli@redhat.com wrote:
>> From: Xiubo Li <xiubli@redhat.com>
>>
>> This patch adds 1 tcmu attr to reset and complete all the blocked
>> netlink waiting threads. It's used when the userspace daemon like
>> tcmu-runner has crashed or forced to shutdown just before the
>> netlink requests be replied to the kernel, then the netlink requeting
>> threads will get stuck forever. We must reboot the machine to recover
>> from it and by this the rebootng is not a must then.
>>
>> The Call Trace will be something like:
>> =======
>> INFO: task targetctl:22655 blocked for more than 120 seconds.
>> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
>> targetctl       D ffff880169718fd0     0 22655  17249 0x00000080
>> Call Trace:
>>   [<ffffffff816ab6d9>] schedule+0x29/0x70
>>   [<ffffffff816a90e9>] schedule_timeout+0x239/0x2c0
>>   [<ffffffff81574d42>] ? skb_release_data+0xf2/0x140
>>   [<ffffffff816aba8d>] wait_for_completion+0xfd/0x140
>>   [<ffffffff810c6440>] ? wake_up_state+0x20/0x20
>>   [<ffffffffc0159f5a>] tcmu_netlink_event+0x26a/0x3a0 [target_core_user]
>>   [<ffffffff810b34b0>] ? wake_up_atomic_t+0x30/0x30
>>   [<ffffffffc015a2c6>] tcmu_configure_device+0x236/0x350 [target_core_user]
>>   [<ffffffffc05085df>] target_configure_device+0x3f/0x3b0 [target_core_mod]
>>   [<ffffffffc0502e7c>] target_core_store_dev_enable+0x2c/0x60 [target_core_mod]
>>   [<ffffffffc0501244>] target_core_dev_store+0x24/0x40 [target_core_mod]
>>   [<ffffffff8128a0e4>] configfs_write_file+0xc4/0x130
>>   [<ffffffff81202aed>] vfs_write+0xbd/0x1e0
>>   [<ffffffff812038ff>] SyS_write+0x7f/0xe0
>>   [<ffffffff816b89fd>] system_call_fastpath+0x16/0x1b
>> =======
>>
>> Signed-off-by: Xiubo Li <xiubli@redhat.com>
>> ---
>> Changes since v1(suggested by Mike Christie):
>> v2: - Makes the reset per device.
>> v3: - Remove nl_cmd->complete, use status instead
>>      - Fix lock issue
>>      - Check if a nl command is even waiting before trying to wake up
>>
>>   drivers/target/target_core_user.c | 60 +++++++++++++++++++++++++++++++++------
>>   1 file changed, 51 insertions(+), 9 deletions(-)
>>
>> diff --git a/drivers/target/target_core_user.c b/drivers/target/target_core_user.c
>> index 4ad89ea..a831f5b7 100644
>> --- a/drivers/target/target_core_user.c
>> +++ b/drivers/target/target_core_user.c
>> @@ -104,8 +104,8 @@ struct tcmu_hba {
>>   #define TCMU_CONFIG_LEN 256
>>   
>>   struct tcmu_nl_cmd {
>> -	/* wake up thread waiting for reply */
>> -	struct completion complete;
>> +	unsigned int waiter;
>> +
>>   	int cmd;
>>   	int status;
>>   };
>> @@ -159,9 +159,12 @@ struct tcmu_dev {
>>   
>>   	spinlock_t nl_cmd_lock;
>>   	struct tcmu_nl_cmd curr_nl_cmd;
>> -	/* wake up threads waiting on curr_nl_cmd */
>> +	/* wake up threads waiting on nl_cmd_wq */
>>   	wait_queue_head_t nl_cmd_wq;
>>   
>> +	/* complete thread waiting complete_wq */
>> +	wait_queue_head_t complete_wq;
>> +
>>   	char dev_config[TCMU_CONFIG_LEN];
>>   
>>   	int nl_reply_supported;
>> @@ -307,11 +310,13 @@ static int tcmu_genl_cmd_done(struct genl_info *info, int completed_cmd)
>>   		nl_cmd->status = rc;
>>   	}
>>   
>> -	spin_unlock(&udev->nl_cmd_lock);
>>   	if (!is_removed)
>>   		 target_undepend_item(&dev->dev_group.cg_item);
>> -	if (!ret)
>> -		complete(&nl_cmd->complete);
>> +	if (!ret && nl_cmd->waiter) {
>> +		nl_cmd->waiter--;
>> +		wake_up(&udev->complete_wq);
>> +	}
>> +	spin_unlock(&udev->nl_cmd_lock);
>>   	return ret;
>>   }
>>   
>> @@ -1258,6 +1263,7 @@ static struct se_device *tcmu_alloc_device(struct se_hba *hba, const char *name)
>>   	timer_setup(&udev->cmd_timer, tcmu_cmd_timedout, 0);
>>   
>>   	init_waitqueue_head(&udev->nl_cmd_wq);
>> +	init_waitqueue_head(&udev->complete_wq);
>>   	spin_lock_init(&udev->nl_cmd_lock);
>>   
>>   	INIT_RADIX_TREE(&udev->data_blocks, GFP_KERNEL);
>> @@ -1554,8 +1560,8 @@ static void tcmu_init_genl_cmd_reply(struct tcmu_dev *udev, int cmd)
>>   	}
>>   
>>   	memset(nl_cmd, 0, sizeof(*nl_cmd));
>> +	nl_cmd->status = 1;
>>   	nl_cmd->cmd = cmd;
>> -	init_completion(&nl_cmd->complete);
>>   
>>   	spin_unlock(&udev->nl_cmd_lock);
>>   }
>> @@ -1572,13 +1578,16 @@ static int tcmu_wait_genl_cmd_reply(struct tcmu_dev *udev)
>>   	if (udev->nl_reply_supported <= 0)
>>   		return 0;
>>   
>> +	spin_lock(&udev->nl_cmd_lock);
>> +	nl_cmd->waiter++;
>> +	spin_unlock(&udev->nl_cmd_lock);
>> +
>>   	pr_debug("sleeping for nl reply\n");
>> -	wait_for_completion(&nl_cmd->complete);
>> +	wait_event(udev->complete_wq, nl_cmd->status != 1);
>>   
>>   	spin_lock(&udev->nl_cmd_lock);
>>   	nl_cmd->cmd = TCMU_CMD_UNSPEC;
>>   	ret = nl_cmd->status;
>> -	nl_cmd->status = 0;
>>   	spin_unlock(&udev->nl_cmd_lock);
>>   
>>   	wake_up_all(&udev->nl_cmd_wq);
>> @@ -2323,6 +2332,38 @@ static ssize_t tcmu_block_dev_store(struct config_item *item, const char *page,
>>   }
>>   CONFIGFS_ATTR(tcmu_, block_dev);
>>   
>> +static ssize_t tcmu_reset_netlink_store(struct config_item *item, const char *page,
>> +				    size_t count)
>> +{
>> +	struct se_device *se_dev = container_of(to_config_group(item),
>> +						struct se_device,
>> +						dev_action_group);
>> +	struct tcmu_dev *udev = TCMU_DEV(se_dev);
>> +	struct tcmu_nl_cmd *nl_cmd = &udev->curr_nl_cmd;
>> +	u8 val;
>> +	int ret;
>> +
>> +	ret = kstrtou8(page, 0, &val);
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	if (val != 1) {
>> +		pr_err("Invalid reset value %d\n", val);
>> +		return -EINVAL;
>> +	}
>> +
>> +	spin_lock(&udev->nl_cmd_lock);
>> +	if (nl_cmd->waiter) {
>> +		nl_cmd->waiter--;
>> +		nl_cmd->status = -EINTR;
>> +		wake_up(&udev->complete_wq);
>> +	}
>> +	spin_unlock(&udev->nl_cmd_lock);
>> +
>> +	return count;
>> +}
>> +CONFIGFS_ATTR_WO(tcmu_, reset_netlink);
>> +
>>   static ssize_t tcmu_reset_ring_store(struct config_item *item, const char *page,
>>   				     size_t count)
>>   {
>> @@ -2363,6 +2404,7 @@ static ssize_t tcmu_reset_ring_store(struct config_item *item, const char *page,
>>   static struct configfs_attribute *tcmu_action_attrs[] = {
>>   	&tcmu_attr_block_dev,
>>   	&tcmu_attr_reset_ring,
>> +	&tcmu_attr_reset_netlink,
>>   	NULL,
>>   };
>>   
>>
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