[PATCH 2/5] scsi:scsi_debug: Define grammar to remove added error injection

[Wenchao Hao <haowenchao2@huawei.com>]

The grammar to remove error injection is a line with fixed 3 columns
separated by spaces.

First column is fixed to "-". It tells this is a removal operation.
Second column is the error code to match.
Third column is the scsi command to match.

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

  echo "- 0 0x12" > /sys/class/scsi_device/0:0:0:1/device/error_inect/error

Signed-off-by: Wenchao Hao <haowenchao2@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 8cfa19f8b034..e5ee75ce6d27 100644
--- a/drivers/scsi/scsi_debug.c
+++ b/drivers/scsi/scsi_debug.c
@@ -7609,6 +7609,30 @@ 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)
 {
@@ -7654,6 +7678,9 @@ 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