scsi: cxlflash: Wait for active AFU commands to timeout upon tear down

With the removal of the static private command pool, the ability to
'complete' outstanding commands was lost. While not an issue for the
commands originating outside the driver, internal AFU commands are
synchronous and therefore have a timeout associated with them. To
avoid a stale memory access, the tear down sequence needs to ensure
that there are not any active commands before proceeding. As these
internal AFU commands are rare events, the simplest way to accomplish
this is detecting the activity and waiting for it to timeout.

Signed-off-by: Matthew R. Ochs <mrochs@linux.vnet.ibm.com>
Acked-by: Uma Krishnan <ukrishn@linux.vnet.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/cxlflash/common.h b/drivers/scsi/cxlflash/common.h
index 7e4ba31935b5546b2d7adb77ed6d3c14420f23cc..621167794026d57eb9ff6424ffb49f43a5f2d9e1 100644 (file)
--- a/drivers/scsi/cxlflash/common.h
+++ b/drivers/scsi/cxlflash/common.h
@@ -180,6 +180,7 @@ struct afu {
        u64 *hrrq_end;
        u64 *hrrq_curr;
        bool toggle;
+       atomic_t cmds_active;   /* Number of currently active AFU commands */
        s64 room;
        spinlock_t rrin_slock; /* Lock to rrin queuing and cmd_room updates */
        u64 hb;

diff --git a/drivers/scsi/cxlflash/main.c b/drivers/scsi/cxlflash/main.c
index 19156adb0b6945a0ff5d9902f925b4c8ed0e52cd..839eca4c4e02d7dff9f3ef6c8797f0176792e1c5 100644 (file)
--- a/drivers/scsi/cxlflash/main.c
+++ b/drivers/scsi/cxlflash/main.c
@@ -531,7 +531,7 @@ static void free_mem(struct cxlflash_cfg *cfg)
  *
  * Safe to call with AFU in a partially allocated/initialized state.
  *
- * Cleans up all state associated with the command queue, and unmaps
+ * Waits for any active internal AFU commands to timeout and then unmaps
  * the MMIO space.
  */
 static void stop_afu(struct cxlflash_cfg *cfg)
@@ -539,6 +539,8 @@ static void stop_afu(struct cxlflash_cfg *cfg)
        struct afu *afu = cfg->afu;
 
        if (likely(afu)) {
+               while (atomic_read(&afu->cmds_active))
+                       ssleep(1);
                if (likely(afu->afu_map)) {
                        cxl_psa_unmap((void __iomem *)afu->afu_map);
                        afu->afu_map = NULL;
@@ -1721,6 +1723,7 @@ int cxlflash_afu_sync(struct afu *afu, ctx_hndl_t ctx_hndl_u,
        }
 
        mutex_lock(&sync_active);
+       atomic_inc(&afu->cmds_active);
        buf = kzalloc(sizeof(*cmd) + __alignof__(*cmd) - 1, GFP_KERNEL);
        if (unlikely(!buf)) {
                dev_err(dev, "%s: no memory for command\n", __func__);
@@ -1762,6 +1765,7 @@ int cxlflash_afu_sync(struct afu *afu, ctx_hndl_t ctx_hndl_u,
                     (cmd->sa.host_use_b[0] & B_ERROR)))
                rc = -1;
 out:
+       atomic_dec(&afu->cmds_active);
        mutex_unlock(&sync_active);
        kfree(buf);
        pr_debug("%s: returning rc=%d\n", __func__, rc);