[PATCH v2 3/4] scsi: don't lock AioContext in I/O code path

[Stefan Hajnoczi]

blk_aio_*() doesn't require the AioContext lock and the SCSI subsystem's
internal state also does not anymore.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Acked-by: Kevin Wolf <kwolf@redhat.com>
---
 hw/scsi/scsi-disk.c    | 23 -----------------------
 hw/scsi/scsi-generic.c | 20 +++-----------------
 2 files changed, 3 insertions(+), 40 deletions(-)

diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c
index 6691f5edb8..2c1bbb3530 100644
--- a/hw/scsi/scsi-disk.c
+++ b/hw/scsi/scsi-disk.c
@@ -273,8 +273,6 @@ static void scsi_aio_complete(void *opaque, int ret)
     SCSIDiskReq *r = (SCSIDiskReq *)opaque;
     SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, r->req.dev);
 
-    aio_context_acquire(blk_get_aio_context(s->qdev.conf.blk));
-
     assert(r->req.aiocb != NULL);
     r->req.aiocb = NULL;
 
@@ -286,7 +284,6 @@ static void scsi_aio_complete(void *opaque, int ret)
     scsi_req_complete(&r->req, GOOD);
 
 done:
-    aio_context_release(blk_get_aio_context(s->qdev.conf.blk));
     scsi_req_unref(&r->req);
 }
 
@@ -394,8 +391,6 @@ static void scsi_read_complete(void *opaque, int ret)
     SCSIDiskReq *r = (SCSIDiskReq *)opaque;
     SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, r->req.dev);
 
-    aio_context_acquire(blk_get_aio_context(s->qdev.conf.blk));
-
     assert(r->req.aiocb != NULL);
     r->req.aiocb = NULL;
 
@@ -406,7 +401,6 @@ static void scsi_read_complete(void *opaque, int ret)
         trace_scsi_disk_read_complete(r->req.tag, r->qiov.size);
     }
     scsi_read_complete_noio(r, ret);
-    aio_context_release(blk_get_aio_context(s->qdev.conf.blk));
 }
 
 /* Actually issue a read to the block device.  */
@@ -448,8 +442,6 @@ static void scsi_do_read_cb(void *opaque, int ret)
     SCSIDiskReq *r = (SCSIDiskReq *)opaque;
     SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, r->req.dev);
 
-    aio_context_acquire(blk_get_aio_context(s->qdev.conf.blk));
-
     assert (r->req.aiocb != NULL);
     r->req.aiocb = NULL;
 
@@ -459,7 +451,6 @@ static void scsi_do_read_cb(void *opaque, int ret)
         block_acct_done(blk_get_stats(s->qdev.conf.blk), &r->acct);
     }
     scsi_do_read(opaque, ret);
-    aio_context_release(blk_get_aio_context(s->qdev.conf.blk));
 }
 
 /* Read more data from scsi device into buffer.  */
@@ -533,8 +524,6 @@ static void scsi_write_complete(void * opaque, int ret)
     SCSIDiskReq *r = (SCSIDiskReq *)opaque;
     SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, r->req.dev);
 
-    aio_context_acquire(blk_get_aio_context(s->qdev.conf.blk));
-
     assert (r->req.aiocb != NULL);
     r->req.aiocb = NULL;
 
@@ -544,7 +533,6 @@ static void scsi_write_complete(void * opaque, int ret)
         block_acct_done(blk_get_stats(s->qdev.conf.blk), &r->acct);
     }
     scsi_write_complete_noio(r, ret);
-    aio_context_release(blk_get_aio_context(s->qdev.conf.blk));
 }
 
 static void scsi_write_data(SCSIRequest *req)
@@ -1742,8 +1730,6 @@ static void scsi_unmap_complete(void *opaque, int ret)
     SCSIDiskReq *r = data->r;
     SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, r->req.dev);
 
-    aio_context_acquire(blk_get_aio_context(s->qdev.conf.blk));
-
     assert(r->req.aiocb != NULL);
     r->req.aiocb = NULL;
 
@@ -1754,7 +1740,6 @@ static void scsi_unmap_complete(void *opaque, int ret)
         block_acct_done(blk_get_stats(s->qdev.conf.blk), &r->acct);
         scsi_unmap_complete_noio(data, ret);
     }
-    aio_context_release(blk_get_aio_context(s->qdev.conf.blk));
 }
 
 static void scsi_disk_emulate_unmap(SCSIDiskReq *r, uint8_t *inbuf)
@@ -1822,8 +1807,6 @@ static void scsi_write_same_complete(void *opaque, int 
ret)
     SCSIDiskReq *r = data->r;
     SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, r->req.dev);
 
-    aio_context_acquire(blk_get_aio_context(s->qdev.conf.blk));
-
     assert(r->req.aiocb != NULL);
     r->req.aiocb = NULL;
 
@@ -1847,7 +1830,6 @@ static void scsi_write_same_complete(void *opaque, int 
ret)
                                        data->sector << BDRV_SECTOR_BITS,
                                        &data->qiov, 0,
                                        scsi_write_same_complete, data);
-        aio_context_release(blk_get_aio_context(s->qdev.conf.blk));
         return;
     }
 
@@ -1857,7 +1839,6 @@ done:
     scsi_req_unref(&r->req);
     qemu_vfree(data->iov.iov_base);
     g_free(data);
-    aio_context_release(blk_get_aio_context(s->qdev.conf.blk));
 }
 
 static void scsi_disk_emulate_write_same(SCSIDiskReq *r, uint8_t *inbuf)
@@ -2810,7 +2791,6 @@ static void scsi_block_sgio_complete(void *opaque, int 
ret)
 {
     SCSIBlockReq *req = (SCSIBlockReq *)opaque;
     SCSIDiskReq *r = &req->req;
-    SCSIDevice *s = r->req.dev;
     sg_io_hdr_t *io_hdr = &req->io_header;
 
     if (ret == 0) {
@@ -2827,13 +2807,10 @@ static void scsi_block_sgio_complete(void *opaque, int 
ret)
         }
 
         if (ret > 0) {
-            aio_context_acquire(blk_get_aio_context(s->conf.blk));
             if (scsi_handle_rw_error(r, ret, true)) {
-                aio_context_release(blk_get_aio_context(s->conf.blk));
                 scsi_req_unref(&r->req);
                 return;
             }
-            aio_context_release(blk_get_aio_context(s->conf.blk));
 
             /* Ignore error.  */
             ret = 0;
diff --git a/hw/scsi/scsi-generic.c b/hw/scsi/scsi-generic.c
index 2417f0ad84..b7b04e1d63 100644
--- a/hw/scsi/scsi-generic.c
+++ b/hw/scsi/scsi-generic.c
@@ -109,15 +109,11 @@ done:
 static void scsi_command_complete(void *opaque, int ret)
 {
     SCSIGenericReq *r = (SCSIGenericReq *)opaque;
-    SCSIDevice *s = r->req.dev;
-
-    aio_context_acquire(blk_get_aio_context(s->conf.blk));
 
     assert(r->req.aiocb != NULL);
     r->req.aiocb = NULL;
 
     scsi_command_complete_noio(r, ret);
-    aio_context_release(blk_get_aio_context(s->conf.blk));
 }
 
 static int execute_command(BlockBackend *blk,
@@ -274,14 +270,12 @@ static void scsi_read_complete(void * opaque, int ret)
     SCSIDevice *s = r->req.dev;
     int len;
 
-    aio_context_acquire(blk_get_aio_context(s->conf.blk));
-
     assert(r->req.aiocb != NULL);
     r->req.aiocb = NULL;
 
     if (ret || r->req.io_canceled) {
         scsi_command_complete_noio(r, ret);
-        goto done;
+        return;
     }
 
     len = r->io_header.dxfer_len - r->io_header.resid;
@@ -320,7 +314,7 @@ static void scsi_read_complete(void * opaque, int ret)
         r->io_header.status != GOOD ||
         len == 0) {
         scsi_command_complete_noio(r, 0);
-        goto done;
+        return;
     }
 
     /* Snoop READ CAPACITY output to set the blocksize.  */
@@ -356,9 +350,6 @@ static void scsi_read_complete(void * opaque, int ret)
 req_complete:
     scsi_req_data(&r->req, len);
     scsi_req_unref(&r->req);
-
-done:
-    aio_context_release(blk_get_aio_context(s->conf.blk));
 }
 
 /* Read more data from scsi device into buffer.  */
@@ -391,14 +382,12 @@ static void scsi_write_complete(void * opaque, int ret)
 
     trace_scsi_generic_write_complete(ret);
 
-    aio_context_acquire(blk_get_aio_context(s->conf.blk));
-
     assert(r->req.aiocb != NULL);
     r->req.aiocb = NULL;
 
     if (ret || r->req.io_canceled) {
         scsi_command_complete_noio(r, ret);
-        goto done;
+        return;
     }
 
     if (r->req.cmd.buf[0] == MODE_SELECT && r->req.cmd.buf[4] == 12 &&
@@ -408,9 +397,6 @@ static void scsi_write_complete(void * opaque, int ret)
     }
 
     scsi_command_complete_noio(r, ret);
-
-done:
-    aio_context_release(blk_get_aio_context(s->conf.blk));
 }
 
 /* Write data to a scsi device.  Returns nonzero on failure.
-- 
2.43.0