[RFC PATCH 2/5] scsi:scsi_debug: Add interface to remove injection which has been added

[Wenchao Hao <haowenchao@huawei.com>]

The removal interface is still "/sys/block/sdX/device/error_inect/error".
The format is still line-by-line integer separated by spaces with fixed 3
column.
  first column is "-", which tells this is a removal operation;
  second column is error code;
  third column is the scsi command.

For example the following command would remove timeout injection of
inquiry command.

  echo "- 0 0x12" > /sys/block/sdb/device/error_inect/error

Signed-off-by: Wenchao Hao <haowenchao@huawei.com>
---
 drivers/scsi/scsi_debug.c | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
index 0cdc9599b628..06e3150812fa 100644
--- a/drivers/scsi/scsi_debug.c
+++ b/drivers/scsi/scsi_debug.c
@@ -7653,6 +7653,30 @@ static void sdebug_err_add(struct device *dev, struct sdebug_err_inject *new)
 	list_add_tail(&new->list, &devip->inject_err_list);
 }
 
+static int sdebug_err_remove(struct device *dev, const char *buf, size_t count)
+{
+	struct scsi_device *sdev = to_scsi_device(dev);
+	struct sdebug_dev_info *devip = (struct sdebug_dev_info *)sdev->hostdata;
+	struct sdebug_err_inject *tmp, *err;
+	int type;
+	unsigned char cmd;
+
+	if (sscanf(buf, "- %d %hhx", &type, &cmd) != 2)
+		return -EINVAL;
+
+	list_for_each_entry_safe(err, tmp, &devip->inject_err_list, list) {
+		if (err->type == type && err->cmd == cmd) {
+			sdev_printk(KERN_INFO, sdev, "Remove %d 0x%x\n",
+				err->type, err->cmd);
+			list_del(&err->list);
+			kfree(err);
+			return count;
+		}
+	}
+
+	return -EINVAL;
+}
+
 static ssize_t error_show(struct device *dev, struct device_attribute *attr,
 		char *buf)
 {
@@ -7698,6 +7722,9 @@ static ssize_t error_store(struct device *dev, struct device_attribute *attr,
 	unsigned int inject_type;
 	struct sdebug_err_inject *inject;
 
+	if (buf[0] == '-')
+		return sdebug_err_remove(dev, buf, count);
+
 	if (sscanf(buf, "%d", &inject_type) != 1)
 		return -EINVAL;
 
-- 
2.35.3