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@xxxxxxxxx>
---
drivers/target/target_core_user.c | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)
diff --git a/drivers/target/target_core_user.c b/drivers/target/target_core_user.c
index 04eda111920e..4ae3103e204c 100644
--- a/drivers/target/target_core_user.c
+++ b/drivers/target/target_core_user.c
@@ -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 +1806,9 @@ 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
+ /* If failure, remove from the list and clear the nl_cmd */
+ tcmu_destroy_genl_cmd_reply(udev);
return ret;
}
--
2.20.1
