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scsi: target: tcmu: clean the nl_cmd of the udev when nl send fails 

If the userspace process crashes while we send the nl msg, it is possible
that the cmd in curr_nl_cmd of tcmu_dev never gets reset to 0, and and
returns busy for other commands after the userspace process is restartd.

More details below:

/backstores/user:file/file> set attribute dev_size=2048
Cannot set attribute dev_size: [Errno 3] No such process
/backstores/user:file/file> set attribute dev_size=2048
Cannot set attribute dev_size: [Errno 16] Device or resource busy

with following kernel messages:
[173605.747169] Unable to reconfigure device
[173616.686674] tcmu daemon: command reply support 1.
[173623.866978] netlink cmd 3 already executing on file
[173623.866984] Unable to reconfigure device

Also, it is not safe to leave the nl_cmd in the list, and not get deleted.

This patch removes the nl_cmd from the list, and clear its data if it is
not sent successfully.

Signed-off-by: Li Zhong <lizhongfs@gmail.com>
Acked-by: Mike Christie <mchristi@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Li Zhong 2019-08-05 08:43:36 +08:00 committed by Martin K. Petersen
parent cb8b3359eb
commit 7d8948627a
1 changed files with 20 additions and 0 deletions
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20
drivers/target/target_core_user.c
View File

@ -1708,6 +1708,24 @@ static int tcmu_init_genl_cmd_reply(struct tcmu_dev *udev, int cmd)
return 0;
}
static void tcmu_destroy_genl_cmd_reply(struct tcmu_dev *udev)
{
struct tcmu_nl_cmd *nl_cmd = &udev->curr_nl_cmd;
if (!tcmu_kern_cmd_reply_supported)
return;
if (udev->nl_reply_supported <= 0)
return;
mutex_lock(&tcmu_nl_cmd_mutex);
list_del(&nl_cmd->nl_list);
memset(nl_cmd, 0, sizeof(*nl_cmd));
mutex_unlock(&tcmu_nl_cmd_mutex);
}
static int tcmu_wait_genl_cmd_reply(struct tcmu_dev *udev)
{
struct tcmu_nl_cmd *nl_cmd = &udev->curr_nl_cmd;
@ -1788,6 +1806,8 @@ static int tcmu_netlink_event_send(struct tcmu_dev *udev,
if (ret == 0 ||
(ret == -ESRCH && cmd == TCMU_CMD_ADDED_DEVICE))
return tcmu_wait_genl_cmd_reply(udev);
else
tcmu_destroy_genl_cmd_reply(udev);
return ret;
}