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 
26 int 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 }
49 EXPORT_SYMBOL(core_tmr_alloc_req);
50 
51 void core_tmr_release_req(struct se_tmr_req *tmr)
52 {
53 	kfree(tmr);
54 }
55 
56 static 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 
71 static 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 
105 void 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 
175 static 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  */
265 static 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 
354 int 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