scsi: scsi_debug: Protect block_unblock_all_queues() with mutex

There is no reason that calls to block_unblock_all_queues() from different
context can't race with one another, so protect with the
sdebug_host_list_mutex. There's no need for a more fine-grained per shost
locking here (and we don't have a per-host lock anyway).

Also simplify some touched code in sdebug_change_qdepth().

Signed-off-by: John Garry <john.g.garry@oracle.com>
Link: https://lore.kernel.org/r/20230327074310.1862889-5-john.g.garry@oracle.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
index a61e7c31dab512afd7371200b42699517e63b4f3..cd05e2f87417952947180ccb500222515fbcae8b 100644 (file)
--- a/drivers/scsi/scsi_debug.c
+++ b/drivers/scsi/scsi_debug.c
@@ -5497,6 +5497,8 @@ static void block_unblock_all_queues(bool block)
        int j;
        struct sdebug_queue *sqp;
 
+       lockdep_assert_held(&sdebug_host_list_mutex);
+
        for (j = 0, sqp = sdebug_q_arr; j < submit_queues; ++j, ++sqp)
                atomic_set(&sqp->blocked, (int)block);
 }
@@ -5511,10 +5513,13 @@ static void tweak_cmnd_count(void)
        modulo = abs(sdebug_every_nth);
        if (modulo < 2)
                return;
+
+       mutex_lock(&sdebug_host_list_mutex);
        block_unblock_all_queues(true);
        count = atomic_read(&sdebug_cmnd_count);
        atomic_set(&sdebug_cmnd_count, (count / modulo) * modulo);
        block_unblock_all_queues(false);
+       mutex_unlock(&sdebug_host_list_mutex);
 }
 
 static void clear_queue_stats(void)
@@ -6036,6 +6041,7 @@ static ssize_t delay_store(struct device_driver *ddp, const char *buf,
                        int j, k;
                        struct sdebug_queue *sqp;
 
+                       mutex_lock(&sdebug_host_list_mutex);
                        block_unblock_all_queues(true);
                        for (j = 0, sqp = sdebug_q_arr; j < submit_queues;
                             ++j, ++sqp) {
@@ -6051,6 +6057,7 @@ static ssize_t delay_store(struct device_driver *ddp, const char *buf,
                                sdebug_ndelay = 0;
                        }
                        block_unblock_all_queues(false);
+                       mutex_unlock(&sdebug_host_list_mutex);
                }
                return res;
        }
@@ -6076,6 +6083,7 @@ static ssize_t ndelay_store(struct device_driver *ddp, const char *buf,
                        int j, k;
                        struct sdebug_queue *sqp;
 
+                       mutex_lock(&sdebug_host_list_mutex);
                        block_unblock_all_queues(true);
                        for (j = 0, sqp = sdebug_q_arr; j < submit_queues;
                             ++j, ++sqp) {
@@ -6092,6 +6100,7 @@ static ssize_t ndelay_store(struct device_driver *ddp, const char *buf,
                                                        : DEF_JDELAY;
                        }
                        block_unblock_all_queues(false);
+                       mutex_unlock(&sdebug_host_list_mutex);
                }
                return res;
        }
@@ -6405,6 +6414,7 @@ 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)) {
+               mutex_lock(&sdebug_host_list_mutex);
                block_unblock_all_queues(true);
                k = 0;
                for (j = 0, sqp = sdebug_q_arr; j < submit_queues;
@@ -6421,6 +6431,7 @@ static ssize_t max_queue_store(struct device_driver *ddp, const char *buf,
                else
                        atomic_set(&retired_max_queue, 0);
                block_unblock_all_queues(false);
+               mutex_unlock(&sdebug_host_list_mutex);
                return count;
        }
        return -EINVAL;
@@ -7352,7 +7363,9 @@ static int sdebug_change_qdepth(struct scsi_device *sdev, int qdepth)
        if (!devip)
                return  -ENODEV;
 
+       mutex_lock(&sdebug_host_list_mutex);
        block_unblock_all_queues(true);
+
        if (qdepth > SDEBUG_CANQUEUE) {
                qdepth = SDEBUG_CANQUEUE;
                pr_warn("%s: requested qdepth [%d] exceeds canqueue [%d], trim\n", __func__,
@@ -7363,9 +7376,12 @@ static int sdebug_change_qdepth(struct scsi_device *sdev, int qdepth)
        if (qdepth != sdev->queue_depth)
                scsi_change_queue_depth(sdev, qdepth);
 
+       block_unblock_all_queues(false);
+       mutex_unlock(&sdebug_host_list_mutex);
+
        if (SDEBUG_OPT_Q_NOISE & sdebug_opts)
                sdev_printk(KERN_INFO, sdev, "%s: qdepth=%d\n", __func__, qdepth);
-       block_unblock_all_queues(false);
+
        return sdev->queue_depth;
 }