1// SPDX-License-Identifier: GPL-2.0-or-later
2/*******************************************************************************
3 * Filename:  target_core_tmr.c
4 *
5 * This file contains SPC-3 task management infrastructure
6 *
7 * (c) Copyright 2009-2013 Datera, Inc.
8 *
9 * Nicholas A. Bellinger <nab@kernel.org>
10 *
11 ******************************************************************************/
12
13#include <linux/slab.h>
14#include <linux/spinlock.h>
15#include <linux/list.h>
16#include <linux/export.h>
17
18#include <target/target_core_base.h>
19#include <target/target_core_backend.h>
20#include <target/target_core_fabric.h>
21
22#include "target_core_internal.h"
23#include "target_core_alua.h"
24#include "target_core_pr.h"
25
26int core_tmr_alloc_req(
27	struct se_cmd *se_cmd,
28	void *fabric_tmr_ptr,
29	u8 function,
30	gfp_t gfp_flags)
31{
32	struct se_tmr_req *tmr;
33
34	tmr = kzalloc(sizeof(struct se_tmr_req), gfp_flags);
35	if (!tmr) {
36		pr_err("Unable to allocate struct se_tmr_req\n");
37		return -ENOMEM;
38	}
39
40	se_cmd->se_cmd_flags |= SCF_SCSI_TMR_CDB;
41	se_cmd->se_tmr_req = tmr;
42	tmr->task_cmd = se_cmd;
43	tmr->fabric_tmr_ptr = fabric_tmr_ptr;
44	tmr->function = function;
45	INIT_LIST_HEAD(&tmr->tmr_list);
46
47	return 0;
48}
49EXPORT_SYMBOL(core_tmr_alloc_req);
50
51void core_tmr_release_req(struct se_tmr_req *tmr)
52{
53	kfree(tmr);
54}
55
56static int target_check_cdb_and_preempt(struct list_head *list,
57		struct se_cmd *cmd)
58{
59	struct t10_pr_registration *reg;
60
61	if (!list)
62		return 0;
63	list_for_each_entry(reg, list, pr_reg_abort_list) {
64		if (reg->pr_res_key == cmd->pr_res_key)
65			return 0;
66	}
67
68	return 1;
69}
70
71static bool __target_check_io_state(struct se_cmd *se_cmd,
72				    struct se_session *tmr_sess, bool tas)
73{
74	struct se_session *sess = se_cmd->se_sess;
75
76	lockdep_assert_held(&sess->sess_cmd_lock);
77
78	/*
79	 * If command already reached CMD_T_COMPLETE state within
80	 * target_complete_cmd() or CMD_T_FABRIC_STOP due to shutdown,
81	 * this se_cmd has been passed to fabric driver and will
82	 * not be aborted.
83	 *
84	 * Otherwise, obtain a local se_cmd->cmd_kref now for TMR
85	 * ABORT_TASK + LUN_RESET for CMD_T_ABORTED processing as
86	 * long as se_cmd->cmd_kref is still active unless zero.
87	 */
88	spin_lock(&se_cmd->t_state_lock);
89	if (se_cmd->transport_state & (CMD_T_COMPLETE | CMD_T_FABRIC_STOP)) {
90		pr_debug("Attempted to abort io tag: %llu already complete or"
91			" fabric stop, skipping\n", se_cmd->tag);
92		spin_unlock(&se_cmd->t_state_lock);
93		return false;
94	}
95	se_cmd->transport_state |= CMD_T_ABORTED;
96
97	if ((tmr_sess != se_cmd->se_sess) && tas)
98		se_cmd->transport_state |= CMD_T_TAS;
99
100	spin_unlock(&se_cmd->t_state_lock);
101
102	return kref_get_unless_zero(&se_cmd->cmd_kref);
103}
104
105void core_tmr_abort_task(
106	struct se_device *dev,
107	struct se_tmr_req *tmr,
108	struct se_session *se_sess)
109{
110	LIST_HEAD(aborted_list);
111	struct se_cmd *se_cmd, *next;
112	unsigned long flags;
113	bool rc;
114	u64 ref_tag;
115	int i;
116
117	for (i = 0; i < dev->queue_cnt; i++) {
118		flush_work(&dev->queues[i].sq.work);
119
120		spin_lock_irqsave(&dev->queues[i].lock, flags);
121		list_for_each_entry_safe(se_cmd, next, &dev->queues[i].state_list,
122					 state_list) {
123			if (se_sess != se_cmd->se_sess)
124				continue;
125
126			/*
127			 * skip task management functions, including
128			 * tmr->task_cmd
129			 */
130			if (se_cmd->se_cmd_flags & SCF_SCSI_TMR_CDB)
131				continue;
132
133			ref_tag = se_cmd->tag;
134			if (tmr->ref_task_tag != ref_tag)
135				continue;
136
137			pr_err("ABORT_TASK: Found referenced %s task_tag: %llu\n",
138			       se_cmd->se_tfo->fabric_name, ref_tag);
139
140			spin_lock(&se_sess->sess_cmd_lock);
141			rc = __target_check_io_state(se_cmd, se_sess, 0);
142			spin_unlock(&se_sess->sess_cmd_lock);
143			if (!rc)
144				continue;
145
146			list_move_tail(&se_cmd->state_list, &aborted_list);
147			se_cmd->state_active = false;
148			spin_unlock_irqrestore(&dev->queues[i].lock, flags);
149
150			if (dev->transport->tmr_notify)
151				dev->transport->tmr_notify(dev, TMR_ABORT_TASK,
152							   &aborted_list);
153
154			list_del_init(&se_cmd->state_list);
155			target_put_cmd_and_wait(se_cmd);
156
157			pr_err("ABORT_TASK: Sending TMR_FUNCTION_COMPLETE for ref_tag: %llu\n",
158			       ref_tag);
159			tmr->response = TMR_FUNCTION_COMPLETE;
160			atomic_long_inc(&dev->aborts_complete);
161			return;
162		}
163		spin_unlock_irqrestore(&dev->queues[i].lock, flags);
164	}
165
166	if (dev->transport->tmr_notify)
167		dev->transport->tmr_notify(dev, TMR_ABORT_TASK, &aborted_list);
168
169	printk("ABORT_TASK: Sending TMR_TASK_DOES_NOT_EXIST for ref_tag: %lld\n",
170			tmr->ref_task_tag);
171	tmr->response = TMR_TASK_DOES_NOT_EXIST;
172	atomic_long_inc(&dev->aborts_no_task);
173}
174
175static void core_tmr_drain_tmr_list(
176	struct se_device *dev,
177	struct se_tmr_req *tmr,
178	struct list_head *preempt_and_abort_list)
179{
180	LIST_HEAD(drain_tmr_list);
181	struct se_session *sess;
182	struct se_tmr_req *tmr_p, *tmr_pp;
183	struct se_cmd *cmd;
184	unsigned long flags;
185	bool rc;
186	/*
187	 * Release all pending and outgoing TMRs aside from the received
188	 * LUN_RESET tmr..
189	 */
190	spin_lock_irqsave(&dev->se_tmr_lock, flags);
191	list_for_each_entry_safe(tmr_p, tmr_pp, &dev->dev_tmr_list, tmr_list) {
192		if (tmr_p == tmr)
193			continue;
194
195		cmd = tmr_p->task_cmd;
196		if (!cmd) {
197			pr_err("Unable to locate struct se_cmd for TMR\n");
198			continue;
199		}
200
201		/*
202		 * We only execute one LUN_RESET at a time so we can't wait
203		 * on them below.
204		 */
205		if (tmr_p->function == TMR_LUN_RESET)
206			continue;
207
208		/*
209		 * If this function was called with a valid pr_res_key
210		 * parameter (eg: for PROUT PREEMPT_AND_ABORT service action
211		 * skip non registration key matching TMRs.
212		 */
213		if (target_check_cdb_and_preempt(preempt_and_abort_list, cmd))
214			continue;
215
216		sess = cmd->se_sess;
217		if (WARN_ON_ONCE(!sess))
218			continue;
219
220		spin_lock(&sess->sess_cmd_lock);
221		rc = __target_check_io_state(cmd, sess, 0);
222		spin_unlock(&sess->sess_cmd_lock);
223
224		if (!rc) {
225			printk("LUN_RESET TMR: non-zero kref_get_unless_zero\n");
226			continue;
227		}
228
229		list_move_tail(&tmr_p->tmr_list, &drain_tmr_list);
230		tmr_p->tmr_dev = NULL;
231	}
232	spin_unlock_irqrestore(&dev->se_tmr_lock, flags);
233
234	list_for_each_entry_safe(tmr_p, tmr_pp, &drain_tmr_list, tmr_list) {
235		list_del_init(&tmr_p->tmr_list);
236		cmd = tmr_p->task_cmd;
237
238		pr_debug("LUN_RESET: %s releasing TMR %p Function: 0x%02x,"
239			" Response: 0x%02x, t_state: %d\n",
240			(preempt_and_abort_list) ? "Preempt" : "", tmr_p,
241			tmr_p->function, tmr_p->response, cmd->t_state);
242
243		target_put_cmd_and_wait(cmd);
244	}
245}
246
247/**
248 * core_tmr_drain_state_list() - abort SCSI commands associated with a device
249 *
250 * @dev:       Device for which to abort outstanding SCSI commands.
251 * @prout_cmd: Pointer to the SCSI PREEMPT AND ABORT if this function is called
252 *             to realize the PREEMPT AND ABORT functionality.
253 * @tmr_sess:  Session through which the LUN RESET has been received.
254 * @tas:       Task Aborted Status (TAS) bit from the SCSI control mode page.
255 *             A quote from SPC-4, paragraph "7.5.10 Control mode page":
256 *             "A task aborted status (TAS) bit set to zero specifies that
257 *             aborted commands shall be terminated by the device server
258 *             without any response to the application client. A TAS bit set
259 *             to one specifies that commands aborted by the actions of an I_T
260 *             nexus other than the I_T nexus on which the command was
261 *             received shall be completed with TASK ABORTED status."
262 * @preempt_and_abort_list: For the PREEMPT AND ABORT functionality, a list
263 *             with registrations that will be preempted.
264 */
265static void core_tmr_drain_state_list(
266	struct se_device *dev,
267	struct se_cmd *prout_cmd,
268	struct se_session *tmr_sess,
269	bool tas,
270	struct list_head *preempt_and_abort_list)
271{
272	LIST_HEAD(drain_task_list);
273	struct se_session *sess;
274	struct se_cmd *cmd, *next;
275	unsigned long flags;
276	int rc, i;
277
278	/*
279	 * Complete outstanding commands with TASK_ABORTED SAM status.
280	 *
281	 * This is following sam4r17, section 5.6 Aborting commands, Table 38
282	 * for TMR LUN_RESET:
283	 *
284	 * a) "Yes" indicates that each command that is aborted on an I_T nexus
285	 * other than the one that caused the SCSI device condition is
286	 * completed with TASK ABORTED status, if the TAS bit is set to one in
287	 * the Control mode page (see SPC-4). "No" indicates that no status is
288	 * returned for aborted commands.
289	 *
290	 * d) If the logical unit reset is caused by a particular I_T nexus
291	 * (e.g., by a LOGICAL UNIT RESET task management function), then "yes"
292	 * (TASK_ABORTED status) applies.
293	 *
294	 * Otherwise (e.g., if triggered by a hard reset), "no"
295	 * (no TASK_ABORTED SAM status) applies.
296	 *
297	 * Note that this seems to be independent of TAS (Task Aborted Status)
298	 * in the Control Mode Page.
299	 */
300	for (i = 0; i < dev->queue_cnt; i++) {
301		flush_work(&dev->queues[i].sq.work);
302
303		spin_lock_irqsave(&dev->queues[i].lock, flags);
304		list_for_each_entry_safe(cmd, next, &dev->queues[i].state_list,
305					 state_list) {
306			/*
307			 * For PREEMPT_AND_ABORT usage, only process commands
308			 * with a matching reservation key.
309			 */
310			if (target_check_cdb_and_preempt(preempt_and_abort_list,
311							 cmd))
312				continue;
313
314			/*
315			 * Not aborting PROUT PREEMPT_AND_ABORT CDB..
316			 */
317			if (prout_cmd == cmd)
318				continue;
319
320			sess = cmd->se_sess;
321			if (WARN_ON_ONCE(!sess))
322				continue;
323
324			spin_lock(&sess->sess_cmd_lock);
325			rc = __target_check_io_state(cmd, tmr_sess, tas);
326			spin_unlock(&sess->sess_cmd_lock);
327			if (!rc)
328				continue;
329
330			list_move_tail(&cmd->state_list, &drain_task_list);
331			cmd->state_active = false;
332		}
333		spin_unlock_irqrestore(&dev->queues[i].lock, flags);
334	}
335
336	if (dev->transport->tmr_notify)
337		dev->transport->tmr_notify(dev, preempt_and_abort_list ?
338					   TMR_LUN_RESET_PRO : TMR_LUN_RESET,
339					   &drain_task_list);
340
341	while (!list_empty(&drain_task_list)) {
342		cmd = list_entry(drain_task_list.next, struct se_cmd, state_list);
343		list_del_init(&cmd->state_list);
344
345		target_show_cmd("LUN_RESET: ", cmd);
346		pr_debug("LUN_RESET: ITT[0x%08llx] - %s pr_res_key: 0x%016Lx\n",
347			 cmd->tag, (preempt_and_abort_list) ? "preempt" : "",
348			 cmd->pr_res_key);
349
350		target_put_cmd_and_wait(cmd);
351	}
352}
353
354int core_tmr_lun_reset(
355        struct se_device *dev,
356        struct se_tmr_req *tmr,
357        struct list_head *preempt_and_abort_list,
358        struct se_cmd *prout_cmd)
359{
360	struct se_node_acl *tmr_nacl = NULL;
361	struct se_portal_group *tmr_tpg = NULL;
362	struct se_session *tmr_sess = NULL;
363	bool tas;
364        /*
365	 * TASK_ABORTED status bit, this is configurable via ConfigFS
366	 * struct se_device attributes.  spc4r17 section 7.4.6 Control mode page
367	 *
368	 * A task aborted status (TAS) bit set to zero specifies that aborted
369	 * tasks shall be terminated by the device server without any response
370	 * to the application client. A TAS bit set to one specifies that tasks
371	 * aborted by the actions of an I_T nexus other than the I_T nexus on
372	 * which the command was received shall be completed with TASK ABORTED
373	 * status (see SAM-4).
374	 */
375	tas = dev->dev_attrib.emulate_tas;
376	/*
377	 * Determine if this se_tmr is coming from a $FABRIC_MOD
378	 * or struct se_device passthrough..
379	 */
380	if (tmr && tmr->task_cmd && tmr->task_cmd->se_sess) {
381		tmr_sess = tmr->task_cmd->se_sess;
382		tmr_nacl = tmr_sess->se_node_acl;
383		tmr_tpg = tmr_sess->se_tpg;
384		if (tmr_nacl && tmr_tpg) {
385			pr_debug("LUN_RESET: TMR caller fabric: %s"
386				" initiator port %s\n",
387				tmr_tpg->se_tpg_tfo->fabric_name,
388				tmr_nacl->initiatorname);
389		}
390	}
391
392
393	/*
394	 * We only allow one reset or preempt and abort to execute at a time
395	 * to prevent one call from claiming all the cmds causing a second
396	 * call from returning while cmds it should have waited on are still
397	 * running.
398	 */
399	mutex_lock(&dev->lun_reset_mutex);
400
401	pr_debug("LUN_RESET: %s starting for [%s], tas: %d\n",
402		(preempt_and_abort_list) ? "Preempt" : "TMR",
403		dev->transport->name, tas);
404	core_tmr_drain_tmr_list(dev, tmr, preempt_and_abort_list);
405	core_tmr_drain_state_list(dev, prout_cmd, tmr_sess, tas,
406				preempt_and_abort_list);
407
408	mutex_unlock(&dev->lun_reset_mutex);
409
410	/*
411	 * Clear any legacy SPC-2 reservation when called during
412	 * LOGICAL UNIT RESET
413	 */
414	if (!preempt_and_abort_list &&
415	     (dev->dev_reservation_flags & DRF_SPC2_RESERVATIONS)) {
416		spin_lock(&dev->dev_reservation_lock);
417		dev->reservation_holder = NULL;
418		dev->dev_reservation_flags &= ~DRF_SPC2_RESERVATIONS;
419		spin_unlock(&dev->dev_reservation_lock);
420		pr_debug("LUN_RESET: SCSI-2 Released reservation\n");
421	}
422
423	atomic_long_inc(&dev->num_resets);
424
425	pr_debug("LUN_RESET: %s for [%s] Complete\n",
426			(preempt_and_abort_list) ? "Preempt" : "TMR",
427			dev->transport->name);
428	return 0;
429}
430
431