Revert "scsi: scsi_debug: Address races following module load"
[sfrench/cifs-2.6.git] / drivers / scsi / scsi_debug.c
index ff78ef702f2263a6b1f04781b19cb5af1e3e9b6d..592a290e6cfaad1d7e0f033c8e941040254aa861 100644 (file)
@@ -32,7 +32,6 @@
 #include <linux/blkdev.h>
 #include <linux/crc-t10dif.h>
 #include <linux/spinlock.h>
-#include <linux/mutex.h>
 #include <linux/interrupt.h>
 #include <linux/atomic.h>
 #include <linux/hrtimer.h>
@@ -732,9 +731,7 @@ static const struct opcode_info_t opcode_info_arr[SDEB_I_LAST_ELEM_P1 + 1] = {
            {0,  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0} },
 };
 
-static atomic_t sdebug_num_hosts;
-static DEFINE_MUTEX(add_host_mutex);
-
+static int sdebug_num_hosts;
 static int sdebug_add_host = DEF_NUM_HOST;  /* in sysfs this is relative */
 static int sdebug_ato = DEF_ATO;
 static int sdebug_cdb_len = DEF_CDB_LEN;
@@ -781,7 +778,6 @@ static int sdebug_uuid_ctl = DEF_UUID_CTL;
 static bool sdebug_random = DEF_RANDOM;
 static bool sdebug_per_host_store = DEF_PER_HOST_STORE;
 static bool sdebug_removable = DEF_REMOVABLE;
-static bool sdebug_deflect_incoming;
 static bool sdebug_clustering;
 static bool sdebug_host_lock = DEF_HOST_LOCK;
 static bool sdebug_strict = DEF_STRICT;
@@ -5122,10 +5118,6 @@ static int scsi_debug_slave_configure(struct scsi_device *sdp)
                       sdp->host->host_no, sdp->channel, sdp->id, sdp->lun);
        if (sdp->host->max_cmd_len != SDEBUG_MAX_CMD_LEN)
                sdp->host->max_cmd_len = SDEBUG_MAX_CMD_LEN;
-       if (smp_load_acquire(&sdebug_deflect_incoming)) {
-               pr_info("Exit early due to deflect_incoming\n");
-               return 1;
-       }
        if (devip == NULL) {
                devip = find_build_dev_info(sdp);
                if (devip == NULL)
@@ -5211,7 +5203,7 @@ static bool stop_queued_cmnd(struct scsi_cmnd *cmnd)
 }
 
 /* Deletes (stops) timers or work queues of all queued commands */
-static void stop_all_queued(bool done_with_no_conn)
+static void stop_all_queued(void)
 {
        unsigned long iflags;
        int j, k;
@@ -5220,15 +5212,13 @@ static void stop_all_queued(bool done_with_no_conn)
        struct sdebug_queued_cmd *sqcp;
        struct sdebug_dev_info *devip;
        struct sdebug_defer *sd_dp;
-       struct scsi_cmnd *scp;
 
        for (j = 0, sqp = sdebug_q_arr; j < submit_queues; ++j, ++sqp) {
                spin_lock_irqsave(&sqp->qc_lock, iflags);
                for (k = 0; k < SDEBUG_CANQUEUE; ++k) {
                        if (test_bit(k, sqp->in_use_bm)) {
                                sqcp = &sqp->qc_arr[k];
-                               scp = sqcp->a_cmnd;
-                               if (!scp)
+                               if (sqcp->a_cmnd == NULL)
                                        continue;
                                devip = (struct sdebug_dev_info *)
                                        sqcp->a_cmnd->device->hostdata;
@@ -5243,10 +5233,6 @@ static void stop_all_queued(bool done_with_no_conn)
                                        l_defer_t = SDEB_DEFER_NONE;
                                spin_unlock_irqrestore(&sqp->qc_lock, iflags);
                                stop_qc_helper(sd_dp, l_defer_t);
-                               if (done_with_no_conn && l_defer_t != SDEB_DEFER_NONE) {
-                                       scp->result = DID_NO_CONNECT << 16;
-                                       scsi_done(scp);
-                               }
                                clear_bit(k, sqp->in_use_bm);
                                spin_lock_irqsave(&sqp->qc_lock, iflags);
                        }
@@ -5389,7 +5375,7 @@ static int scsi_debug_host_reset(struct scsi_cmnd *SCpnt)
                }
        }
        spin_unlock(&sdebug_host_list_lock);
-       stop_all_queued(false);
+       stop_all_queued();
        if (SDEBUG_OPT_RESET_NOISE & sdebug_opts)
                sdev_printk(KERN_INFO, SCpnt->device,
                            "%s: %d device(s) found\n", __func__, k);
@@ -5449,50 +5435,13 @@ static void sdebug_build_parts(unsigned char *ramp, unsigned long store_size)
        }
 }
 
-static void sdeb_block_all_queues(void)
-{
-       int j;
-       struct sdebug_queue *sqp;
-
-       for (j = 0, sqp = sdebug_q_arr; j < submit_queues; ++j, ++sqp)
-               atomic_set(&sqp->blocked, (int)true);
-}
-
-static void sdeb_unblock_all_queues(void)
+static void block_unblock_all_queues(bool block)
 {
        int j;
        struct sdebug_queue *sqp;
 
        for (j = 0, sqp = sdebug_q_arr; j < submit_queues; ++j, ++sqp)
-               atomic_set(&sqp->blocked, (int)false);
-}
-
-static void
-sdeb_add_n_hosts(int num_hosts)
-{
-       if (num_hosts < 1)
-               return;
-       do {
-               bool found;
-               unsigned long idx;
-               struct sdeb_store_info *sip;
-               bool want_phs = (sdebug_fake_rw == 0) && sdebug_per_host_store;
-
-               found = false;
-               if (want_phs) {
-                       xa_for_each_marked(per_store_ap, idx, sip, SDEB_XA_NOT_IN_USE) {
-                               sdeb_most_recent_idx = (int)idx;
-                               found = true;
-                               break;
-                       }
-                       if (found)      /* re-use case */
-                               sdebug_add_host_helper((int)idx);
-                       else
-                               sdebug_do_add_host(true /* make new store */);
-               } else {
-                       sdebug_do_add_host(false);
-               }
-       } while (--num_hosts);
+               atomic_set(&sqp->blocked, (int)block);
 }
 
 /* Adjust (by rounding down) the sdebug_cmnd_count so abs(every_nth)-1
@@ -5505,10 +5454,10 @@ static void tweak_cmnd_count(void)
        modulo = abs(sdebug_every_nth);
        if (modulo < 2)
                return;
-       sdeb_block_all_queues();
+       block_unblock_all_queues(true);
        count = atomic_read(&sdebug_cmnd_count);
        atomic_set(&sdebug_cmnd_count, (count / modulo) * modulo);
-       sdeb_unblock_all_queues();
+       block_unblock_all_queues(false);
 }
 
 static void clear_queue_stats(void)
@@ -5526,15 +5475,6 @@ static bool inject_on_this_cmd(void)
        return (atomic_read(&sdebug_cmnd_count) % abs(sdebug_every_nth)) == 0;
 }
 
-static int process_deflect_incoming(struct scsi_cmnd *scp)
-{
-       u8 opcode = scp->cmnd[0];
-
-       if (opcode == SYNCHRONIZE_CACHE || opcode == SYNCHRONIZE_CACHE_16)
-               return 0;
-       return DID_NO_CONNECT << 16;
-}
-
 #define INCLUSIVE_TIMING_MAX_NS 1000000                /* 1 millisecond */
 
 /* Complete the processing of the thread that queued a SCSI command to this
@@ -5544,7 +5484,8 @@ static int process_deflect_incoming(struct scsi_cmnd *scp)
  */
 static int schedule_resp(struct scsi_cmnd *cmnd, struct sdebug_dev_info *devip,
                         int scsi_result,
-                        int (*pfp)(struct scsi_cmnd *, struct sdebug_dev_info *),
+                        int (*pfp)(struct scsi_cmnd *,
+                                   struct sdebug_dev_info *),
                         int delta_jiff, int ndelay)
 {
        bool new_sd_dp;
@@ -5565,27 +5506,13 @@ static int schedule_resp(struct scsi_cmnd *cmnd, struct sdebug_dev_info *devip,
        }
        sdp = cmnd->device;
 
-       if (delta_jiff == 0) {
-               sqp = get_queue(cmnd);
-               if (atomic_read(&sqp->blocked)) {
-                       if (smp_load_acquire(&sdebug_deflect_incoming))
-                               return process_deflect_incoming(cmnd);
-                       else
-                               return SCSI_MLQUEUE_HOST_BUSY;
-               }
+       if (delta_jiff == 0)
                goto respond_in_thread;
-       }
 
        sqp = get_queue(cmnd);
        spin_lock_irqsave(&sqp->qc_lock, iflags);
        if (unlikely(atomic_read(&sqp->blocked))) {
                spin_unlock_irqrestore(&sqp->qc_lock, iflags);
-               if (smp_load_acquire(&sdebug_deflect_incoming)) {
-                       scsi_result = process_deflect_incoming(cmnd);
-                       goto respond_in_thread;
-               }
-               if (sdebug_verbose)
-                       pr_info("blocked --> SCSI_MLQUEUE_HOST_BUSY\n");
                return SCSI_MLQUEUE_HOST_BUSY;
        }
        num_in_q = atomic_read(&devip->num_in_q);
@@ -5774,12 +5701,8 @@ static int schedule_resp(struct scsi_cmnd *cmnd, struct sdebug_dev_info *devip,
 respond_in_thread:     /* call back to mid-layer using invocation thread */
        cmnd->result = pfp != NULL ? pfp(cmnd, devip) : 0;
        cmnd->result &= ~SDEG_RES_IMMED_MASK;
-       if (cmnd->result == 0 && scsi_result != 0) {
+       if (cmnd->result == 0 && scsi_result != 0)
                cmnd->result = scsi_result;
-               if (sdebug_verbose)
-                       pr_info("respond_in_thread: tag=0x%x, scp->result=0x%x\n",
-                               blk_mq_unique_tag(scsi_cmd_to_rq(cmnd)), scsi_result);
-       }
        scsi_done(cmnd);
        return 0;
 }
@@ -6064,7 +5987,7 @@ static ssize_t delay_store(struct device_driver *ddp, const char *buf,
                        int j, k;
                        struct sdebug_queue *sqp;
 
-                       sdeb_block_all_queues();
+                       block_unblock_all_queues(true);
                        for (j = 0, sqp = sdebug_q_arr; j < submit_queues;
                             ++j, ++sqp) {
                                k = find_first_bit(sqp->in_use_bm,
@@ -6078,7 +6001,7 @@ static ssize_t delay_store(struct device_driver *ddp, const char *buf,
                                sdebug_jdelay = jdelay;
                                sdebug_ndelay = 0;
                        }
-                       sdeb_unblock_all_queues();
+                       block_unblock_all_queues(false);
                }
                return res;
        }
@@ -6104,7 +6027,7 @@ static ssize_t ndelay_store(struct device_driver *ddp, const char *buf,
                        int j, k;
                        struct sdebug_queue *sqp;
 
-                       sdeb_block_all_queues();
+                       block_unblock_all_queues(true);
                        for (j = 0, sqp = sdebug_q_arr; j < submit_queues;
                             ++j, ++sqp) {
                                k = find_first_bit(sqp->in_use_bm,
@@ -6119,7 +6042,7 @@ static ssize_t ndelay_store(struct device_driver *ddp, const char *buf,
                                sdebug_jdelay = ndelay  ? JDELAY_OVERRIDDEN
                                                        : DEF_JDELAY;
                        }
-                       sdeb_unblock_all_queues();
+                       block_unblock_all_queues(false);
                }
                return res;
        }
@@ -6433,7 +6356,7 @@ static ssize_t max_queue_store(struct device_driver *ddp, const char *buf,
        if ((count > 0) && (1 == sscanf(buf, "%d", &n)) && (n > 0) &&
            (n <= SDEBUG_CANQUEUE) &&
            (sdebug_host_max_queue == 0)) {
-               sdeb_block_all_queues();
+               block_unblock_all_queues(true);
                k = 0;
                for (j = 0, sqp = sdebug_q_arr; j < submit_queues;
                     ++j, ++sqp) {
@@ -6448,7 +6371,7 @@ static ssize_t max_queue_store(struct device_driver *ddp, const char *buf,
                        atomic_set(&retired_max_queue, k + 1);
                else
                        atomic_set(&retired_max_queue, 0);
-               sdeb_unblock_all_queues();
+               block_unblock_all_queues(false);
                return count;
        }
        return -EINVAL;
@@ -6537,48 +6460,43 @@ static DRIVER_ATTR_RW(virtual_gb);
 static ssize_t add_host_show(struct device_driver *ddp, char *buf)
 {
        /* absolute number of hosts currently active is what is shown */
-       return scnprintf(buf, PAGE_SIZE, "%d\n", atomic_read(&sdebug_num_hosts));
+       return scnprintf(buf, PAGE_SIZE, "%d\n", sdebug_num_hosts);
 }
 
-/*
- * Accept positive and negative values. Hex values (only positive) may be prefixed by '0x'.
- * To remove all hosts use a large negative number (e.g. -9999). The value 0 does nothing.
- * Returns -EBUSY if another add_host sysfs invocation is active.
- */
 static ssize_t add_host_store(struct device_driver *ddp, const char *buf,
                              size_t count)
 {
+       bool found;
+       unsigned long idx;
+       struct sdeb_store_info *sip;
+       bool want_phs = (sdebug_fake_rw == 0) && sdebug_per_host_store;
        int delta_hosts;
 
-       if (count == 0 || kstrtoint(buf, 0, &delta_hosts))
+       if (sscanf(buf, "%d", &delta_hosts) != 1)
                return -EINVAL;
-       if (sdebug_verbose)
-               pr_info("prior num_hosts=%d, num_to_add=%d\n",
-                       atomic_read(&sdebug_num_hosts), delta_hosts);
-       if (delta_hosts == 0)
-               return count;
-       if (mutex_trylock(&add_host_mutex) == 0)
-               return -EBUSY;
        if (delta_hosts > 0) {
-               sdeb_add_n_hosts(delta_hosts);
-       } else if (delta_hosts < 0) {
-               smp_store_release(&sdebug_deflect_incoming, true);
-               sdeb_block_all_queues();
-               if (delta_hosts >= atomic_read(&sdebug_num_hosts))
-                       stop_all_queued(true);
                do {
-                       if (atomic_read(&sdebug_num_hosts) < 1) {
-                               free_all_queued();
-                               break;
+                       found = false;
+                       if (want_phs) {
+                               xa_for_each_marked(per_store_ap, idx, sip,
+                                                  SDEB_XA_NOT_IN_USE) {
+                                       sdeb_most_recent_idx = (int)idx;
+                                       found = true;
+                                       break;
+                               }
+                               if (found)      /* re-use case */
+                                       sdebug_add_host_helper((int)idx);
+                               else
+                                       sdebug_do_add_host(true);
+                       } else {
+                               sdebug_do_add_host(false);
                        }
+               } while (--delta_hosts);
+       } else if (delta_hosts < 0) {
+               do {
                        sdebug_do_remove_host(false);
                } while (++delta_hosts);
-               sdeb_unblock_all_queues();
-               smp_store_release(&sdebug_deflect_incoming, false);
        }
-       mutex_unlock(&add_host_mutex);
-       if (sdebug_verbose)
-               pr_info("post num_hosts=%d\n", atomic_read(&sdebug_num_hosts));
        return count;
 }
 static DRIVER_ATTR_RW(add_host);
@@ -7089,10 +7007,6 @@ static int __init scsi_debug_init(void)
        sdebug_add_host = 0;
 
        for (k = 0; k < hosts_to_add; k++) {
-               if (smp_load_acquire(&sdebug_deflect_incoming)) {
-                       pr_info("exit early as sdebug_deflect_incoming is set\n");
-                       return 0;
-               }
                if (want_store && k == 0) {
                        ret = sdebug_add_host_helper(idx);
                        if (ret < 0) {
@@ -7110,12 +7024,8 @@ static int __init scsi_debug_init(void)
                }
        }
        if (sdebug_verbose)
-               pr_info("built %d host(s)\n", atomic_read(&sdebug_num_hosts));
+               pr_info("built %d host(s)\n", sdebug_num_hosts);
 
-       /*
-        * Even though all the hosts have been established, due to async device (LU) scanning
-        * by the scsi mid-level, there may still be devices (LUs) being set up.
-        */
        return 0;
 
 bus_unreg:
@@ -7131,17 +7041,12 @@ free_q_arr:
 
 static void __exit scsi_debug_exit(void)
 {
-       int k;
+       int k = sdebug_num_hosts;
 
-       /* Possible race with LUs still being set up; stop them asap */
-       sdeb_block_all_queues();
-       smp_store_release(&sdebug_deflect_incoming, true);
-       stop_all_queued(false);
-       for (k = 0; atomic_read(&sdebug_num_hosts) > 0; k++)
+       stop_all_queued();
+       for (; k; k--)
                sdebug_do_remove_host(true);
        free_all_queued();
-       if (sdebug_verbose)
-               pr_info("removed %d hosts\n", k);
        driver_unregister(&sdebug_driverfs_driver);
        bus_unregister(&pseudo_lld_bus);
        root_device_unregister(pseudo_primary);
@@ -7311,13 +7216,13 @@ static int sdebug_add_host_helper(int per_host_idx)
        sdbg_host->dev.bus = &pseudo_lld_bus;
        sdbg_host->dev.parent = pseudo_primary;
        sdbg_host->dev.release = &sdebug_release_adapter;
-       dev_set_name(&sdbg_host->dev, "adapter%d", atomic_read(&sdebug_num_hosts));
+       dev_set_name(&sdbg_host->dev, "adapter%d", sdebug_num_hosts);
 
        error = device_register(&sdbg_host->dev);
        if (error)
                goto clean;
 
-       atomic_inc(&sdebug_num_hosts);
+       ++sdebug_num_hosts;
        return 0;
 
 clean:
@@ -7381,7 +7286,7 @@ static void sdebug_do_remove_host(bool the_end)
                return;
 
        device_unregister(&sdbg_host->dev);
-       atomic_dec(&sdebug_num_hosts);
+       --sdebug_num_hosts;
 }
 
 static int sdebug_change_qdepth(struct scsi_device *sdev, int qdepth)
@@ -7389,10 +7294,10 @@ static int sdebug_change_qdepth(struct scsi_device *sdev, int qdepth)
        int num_in_q = 0;
        struct sdebug_dev_info *devip;
 
-       sdeb_block_all_queues();
+       block_unblock_all_queues(true);
        devip = (struct sdebug_dev_info *)sdev->hostdata;
        if (NULL == devip) {
-               sdeb_unblock_all_queues();
+               block_unblock_all_queues(false);
                return  -ENODEV;
        }
        num_in_q = atomic_read(&devip->num_in_q);
@@ -7411,7 +7316,7 @@ static int sdebug_change_qdepth(struct scsi_device *sdev, int qdepth)
                sdev_printk(KERN_INFO, sdev, "%s: qdepth=%d, num_in_q=%d\n",
                            __func__, qdepth, num_in_q);
        }
-       sdeb_unblock_all_queues();
+       block_unblock_all_queues(false);
        return sdev->queue_depth;
 }