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Commit cab9609b authored by Nicholas Bellinger's avatar Nicholas Bellinger
Browse files

target: Fix zero-length MODE_SENSE regression 



This patch fixes a regression introduced in v3.8-rc1 code where
a zero-length MODE_SENSE was no longer returning GOOD status, but
instead returning TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE to generate
a CHECK_CONDITION status.

This regression was introduced with the following commit:

  commit de103c93
  Author: Christoph Hellwig <hch@lst.de>
  Date:   Tue Nov 6 12:24:09 2012 -0800

      target: pass sense_reason as a return value

and this patch has been tested with the following zero-length CDB:

  sg_raw /dev/sdd 5a 00 0a 00 00 00 00 00 00 00
  SCSI Status: Good

  Sense Information:
  sense buffer empty

Cc: Christoph Hellwig <hch@lst.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Roland Dreier <roland@purestorage.com>
Signed-off-by: default avatarNicholas Bellinger <nab@linux-iscsi.org>
parent 49df9fc9

drivers/target/target_core_spc.c

+7 −28
Original line number Diff line number Diff line
@@ -850,7 +850,7 @@ static sense_reason_t spc_emulate_modesense(struct se_cmd *cmd) 
{

	struct se_device *dev = cmd->se_dev;

	char *cdb = cmd->t_task_cdb;

	unsigned char *buf, *map_buf;

	unsigned char buf[SE_MODE_PAGE_BUF], *rbuf;

	int type = dev->transport->get_device_type(dev);

	int ten = (cmd->t_task_cdb[0] == MODE_SENSE_10);

	bool dbd = !!(cdb[1] & 0x08);
@@ -862,26 +862,8 @@ static sense_reason_t spc_emulate_modesense(struct se_cmd *cmd) 
	int ret;

	int i;



	map_buf = transport_kmap_data_sg(cmd);

	if (!map_buf)

		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;

	/*

	 * If SCF_PASSTHROUGH_SG_TO_MEM_NOALLOC is not set, then we

	 * know we actually allocated a full page.  Otherwise, if the

	 * data buffer is too small, allocate a temporary buffer so we

	 * don't have to worry about overruns in all our INQUIRY

	 * emulation handling.

	 */

	if (cmd->data_length < SE_MODE_PAGE_BUF &&

	    (cmd->se_cmd_flags & SCF_PASSTHROUGH_SG_TO_MEM_NOALLOC)) {

		buf = kzalloc(SE_MODE_PAGE_BUF, GFP_KERNEL);

		if (!buf) {

			transport_kunmap_data_sg(cmd);

			return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;

		}

	} else {

		buf = map_buf;

	}

	memset(buf, 0, SE_MODE_PAGE_BUF);



	/*

	 * Skip over MODE DATA LENGTH + MEDIUM TYPE fields to byte 3 for

	 * MODE_SENSE_10 and byte 2 for MODE_SENSE (6).
@@ -933,8 +915,6 @@ static sense_reason_t spc_emulate_modesense(struct se_cmd *cmd) 
	if (page == 0x3f) {

		if (subpage != 0x00 && subpage != 0xff) {

			pr_warn("MODE_SENSE: Invalid subpage code: 0x%02x\n", subpage);

			kfree(buf);

			transport_kunmap_data_sg(cmd);

			return TCM_INVALID_CDB_FIELD;

		}
@@ -971,7 +951,6 @@ static sense_reason_t spc_emulate_modesense(struct se_cmd *cmd) 
		pr_err("MODE SENSE: unimplemented page/subpage: 0x%02x/0x%02x\n",

		       page, subpage);



	transport_kunmap_data_sg(cmd);

	return TCM_UNKNOWN_MODE_PAGE;



set_length:
@@ -980,12 +959,12 @@ static sense_reason_t spc_emulate_modesense(struct se_cmd *cmd) 
	else

		buf[0] = length - 1;



	if (buf != map_buf) {

		memcpy(map_buf, buf, cmd->data_length);

		kfree(buf);

	rbuf = transport_kmap_data_sg(cmd);

	if (rbuf) {

		memcpy(rbuf, buf, min_t(u32, SE_MODE_PAGE_BUF, cmd->data_length));

		transport_kunmap_data_sg(cmd);

	}



	transport_kunmap_data_sg(cmd);

	target_complete_cmd(cmd, GOOD);

	return 0;

}