scsi: cxlflash: Use local mutex for AFU serialization

AFUs can only process a single AFU command at a time. This is enforced with
a global mutex situated within the AFU send routine. As this mutex has a
global scope, it has the potential to unnecessarily block commands destined
for other AFUs.

Instead of using a global mutex, transition the mutex to be per-AFU. This
will allow commands to only be blocked by siblings of the same AFU.

Signed-off-by: Matthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-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 89240b84745c84ebe14e201efc28abf832bfcd3e..8908a20065c83c73eca48ecb294a0a4ee23bcb5b 100644 (file)
--- a/drivers/scsi/cxlflash/common.h
+++ b/drivers/scsi/cxlflash/common.h
@@ -240,6 +240,7 @@ struct afu {
        struct cxlflash_afu_map __iomem *afu_map;       /* entire MMIO map */
 
        atomic_t cmds_active;   /* Number of currently active AFU commands */
+       struct mutex sync_active;       /* Mutex to serialize AFU commands */
        u64 hb;
        u32 internal_lun;       /* User-desired LUN mode for this AFU */
 

diff --git a/drivers/scsi/cxlflash/main.c b/drivers/scsi/cxlflash/main.c
index cf0b407f6ebbd990abdaf8872ddc6262fef14fd8..c91e9127fc7957d328517de0932ac32cbde974dc 100644 (file)
--- a/drivers/scsi/cxlflash/main.c
+++ b/drivers/scsi/cxlflash/main.c
@@ -2126,6 +2126,7 @@ static int init_afu(struct cxlflash_cfg *cfg)
 
        cfg->ops->perst_reloads_same_image(cfg->afu_cookie, true);
 
+       mutex_init(&afu->sync_active);
        afu->num_hwqs = afu->desired_hwqs;
        for (i = 0; i < afu->num_hwqs; i++) {
                rc = init_mc(cfg, i);
@@ -2309,7 +2310,6 @@ static int send_afu_cmd(struct afu *afu, struct sisl_ioarcb *rcb)
        char *buf = NULL;
        int rc = 0;
        int nretry = 0;
-       static DEFINE_MUTEX(sync_active);
 
        if (cfg->state != STATE_NORMAL) {
                dev_dbg(dev, "%s: Sync not required state=%u\n",
@@ -2317,7 +2317,7 @@ static int send_afu_cmd(struct afu *afu, struct sisl_ioarcb *rcb)
                return 0;
        }
 
-       mutex_lock(&sync_active);
+       mutex_lock(&afu->sync_active);
        atomic_inc(&afu->cmds_active);
        buf = kmalloc(sizeof(*cmd) + __alignof__(*cmd) - 1, GFP_KERNEL);
        if (unlikely(!buf)) {
@@ -2372,7 +2372,7 @@ static int send_afu_cmd(struct afu *afu, struct sisl_ioarcb *rcb)
                *rcb->ioasa = cmd->sa;
 out:
        atomic_dec(&afu->cmds_active);
-       mutex_unlock(&sync_active);
+       mutex_unlock(&afu->sync_active);
        kfree(buf);
        dev_dbg(dev, "%s: returning rc=%d\n", __func__, rc);
        return rc;