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authorJohn Garry2023-03-27 07:43:09 +0000
committerMartin K. Petersen2023-04-02 22:09:22 -0400
commit57f7225a4fe25425c29402adad990c7409958c40 (patch)
treef91bc3e27318c191731f0c617b6e1e7362ccd2e2 /drivers/scsi
parent12f3eef016ea7a72c6e0d0fe6f66882086d9c4a9 (diff)
scsi: scsi_debug: Only allow sdebug_max_queue be modified when no shosts
The shost->can_queue value is initially used to set per-HW queue context tag depth in the block layer. This ensures that the shost is not sent too many commands which it can deal with. However lowering sdebug_max_queue separately means that we can easily overload the shost, as in the following example: $ cat /sys/bus/pseudo/drivers/scsi_debug/max_queue 192 $ cat /sys/class/scsi_host/host0/can_queue 192 $ echo 100 > /sys/bus/pseudo/drivers/scsi_debug/max_queue $ cat /sys/class/scsi_host/host0/can_queue 192 $ fio --filename=/dev/sda --direct=1 --rw=read --bs=4k --iodepth=256 --runtime=1200 --numjobs=10 --time_based --group_reporting --name=iops-test-job --eta-newline=1 --readonly --ioengine=io_uring --hipri --exitall_on_error iops-test-job: (g=0): rw=read, bs=(R) 4096B-4096B, (W) 4096B-4096B, (T) 4096B-4096B, ioengine=io_uring, iodepth=256 ... fio-3.28 Starting 10 processes [ 111.269885] scsi_io_completion_action: 400 callbacks suppressed [ 111.269885] blk_print_req_error: 400 callbacks suppressed [ 111.269889] I/O error, dev sda, sector 440 op 0x0:(READ) flags 0x1200000 phys_seg 1 prio class 2 [ 111.269892] sd 0:0:0:0: [sda] tag#132 FAILED Result: hostbyte=DID_ABORT driverbyte=DRIVER_OK cmd_age=0s [ 111.269897] sd 0:0:0:0: [sda] tag#132 CDB: Read(10) 28 00 00 00 01 68 00 00 08 00 [ 111.277058] I/O error, dev sda, sector 360 op 0x0:(READ) flags 0x1200000 phys_seg 1 prio class 2 [...] Ensure that this cannot happen by allowing sdebug_max_queue be modified only when we have no shosts. As such, any shost->can_queue value will match sdebug_max_queue, and sdebug_max_queue cannot be modified separately. Since retired_max_queue is no longer set, remove support. Continue to apply the restriction that sdebug_host_max_queue cannot be modified when sdebug_host_max_queue is set. Adding support for that would mean extra code, and no one has complained about this restriction previously. A command like the following may be used to remove a shost: echo -1 > /sys/bus/pseudo/drivers/scsi_debug/add_host Signed-off-by: John Garry <john.g.garry@oracle.com> Link: https://lore.kernel.org/r/20230327074310.1862889-11-john.g.garry@oracle.com Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Diffstat (limited to 'drivers/scsi')
-rw-r--r--drivers/scsi/scsi_debug.c67
1 files changed, 6 insertions, 61 deletions
diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
index 9a741b1983ca..66b0c831da3b 100644
--- a/drivers/scsi/scsi_debug.c
+++ b/drivers/scsi/scsi_debug.c
@@ -762,7 +762,6 @@ static int sdebug_max_luns = DEF_MAX_LUNS;
static int sdebug_max_queue = SDEBUG_CANQUEUE; /* per submit queue */
static unsigned int sdebug_medium_error_start = OPT_MEDIUM_ERR_ADDR;
static int sdebug_medium_error_count = OPT_MEDIUM_ERR_NUM;
-static atomic_t retired_max_queue; /* if > 0 then was prior max_queue */
static int sdebug_ndelay = DEF_NDELAY; /* if > 0 then unit is nanoseconds */
static int sdebug_no_lun_0 = DEF_NO_LUN_0;
static int sdebug_no_uld;
@@ -4928,7 +4927,6 @@ static void sdebug_q_cmd_complete(struct sdebug_defer *sd_dp)
{
struct sdebug_queued_cmd *sqcp = container_of(sd_dp, struct sdebug_queued_cmd, sd_dp);
int qc_idx;
- int retiring = 0;
unsigned long flags, iflags;
struct scsi_cmnd *scp = sqcp->scmd;
struct sdebug_scsi_cmd *sdsc;
@@ -4959,9 +4957,6 @@ static void sdebug_q_cmd_complete(struct sdebug_defer *sd_dp)
sd_dp->aborted = false;
ASSIGN_QUEUED_CMD(scp, NULL);
- if (unlikely(atomic_read(&retired_max_queue) > 0))
- retiring = 1;
-
sqp->qc_arr[qc_idx] = NULL;
if (unlikely(!test_and_clear_bit(qc_idx, sqp->in_use_bm))) {
spin_unlock_irqrestore(&sdsc->lock, flags);
@@ -4970,23 +4965,6 @@ static void sdebug_q_cmd_complete(struct sdebug_defer *sd_dp)
goto out;
}
- if (unlikely(retiring)) { /* user has reduced max_queue */
- int k, retval;
-
- retval = atomic_read(&retired_max_queue);
- if (qc_idx >= retval) {
- spin_unlock_irqrestore(&sdsc->lock, flags);
- spin_unlock_irqrestore(&sqp->qc_lock, iflags);
- pr_err("index %d too large\n", retval);
- goto out;
- }
- k = find_last_bit(sqp->in_use_bm, retval);
- if ((k < sdebug_max_queue) || (k == retval))
- atomic_set(&retired_max_queue, 0);
- else
- atomic_set(&retired_max_queue, k + 1);
- }
-
spin_unlock_irqrestore(&sdsc->lock, flags);
spin_unlock_irqrestore(&sqp->qc_lock, iflags);
@@ -6431,29 +6409,18 @@ static ssize_t max_queue_show(struct device_driver *ddp, char *buf)
static ssize_t max_queue_store(struct device_driver *ddp, const char *buf,
size_t count)
{
- int j, n, k, a;
- struct sdebug_queue *sqp;
+ int n;
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;
- ++j, ++sqp) {
- a = find_last_bit(sqp->in_use_bm, SDEBUG_CANQUEUE);
- if (a > k)
- k = a;
- }
- sdebug_max_queue = n;
- if (k == SDEBUG_CANQUEUE)
- atomic_set(&retired_max_queue, 0);
- else if (k >= n)
- atomic_set(&retired_max_queue, k + 1);
+
+ /* We may only change sdebug_max_queue when we have no shosts */
+ if (list_empty(&sdebug_host_list))
+ sdebug_max_queue = n;
else
- atomic_set(&retired_max_queue, 0);
- block_unblock_all_queues(false);
+ count = -EBUSY;
mutex_unlock(&sdebug_host_list_mutex);
return count;
}
@@ -6882,7 +6849,6 @@ static int __init scsi_debug_init(void)
ramdisk_lck_a[0] = &atomic_rw;
ramdisk_lck_a[1] = &atomic_rw2;
- atomic_set(&retired_max_queue, 0);
if (sdebug_ndelay >= 1000 * 1000 * 1000) {
pr_warn("ndelay must be less than 1 second, ignored\n");
@@ -7520,7 +7486,6 @@ static bool sdebug_blk_mq_poll_iter(struct request *rq, void *opaque)
struct sdebug_queue *sqp;
unsigned long flags;
int queue_num = data->queue_num;
- bool retiring = false;
int qc_idx;
ktime_t time;
@@ -7554,9 +7519,6 @@ static bool sdebug_blk_mq_poll_iter(struct request *rq, void *opaque)
return true;
}
- if (unlikely(atomic_read(&retired_max_queue) > 0))
- retiring = true;
-
qc_idx = sd_dp->sqa_idx;
sqp->qc_arr[qc_idx] = NULL;
if (unlikely(!test_and_clear_bit(qc_idx, sqp->in_use_bm))) {
@@ -7567,23 +7529,6 @@ static bool sdebug_blk_mq_poll_iter(struct request *rq, void *opaque)
return true;
}
- if (unlikely(retiring)) { /* user has reduced max_queue */
- int k, retval = atomic_read(&retired_max_queue);
-
- if (qc_idx >= retval) {
- pr_err("index %d too large\n", retval);
- spin_unlock_irqrestore(&sdsc->lock, flags);
- sdebug_free_queued_cmd(sqcp);
- return true;
- }
-
- k = find_last_bit(sqp->in_use_bm, retval);
- if ((k < sdebug_max_queue) || (k == retval))
- atomic_set(&retired_max_queue, 0);
- else
- atomic_set(&retired_max_queue, k + 1);
- }
-
ASSIGN_QUEUED_CMD(cmd, NULL);
spin_unlock_irqrestore(&sdsc->lock, flags);