diff mbox

[PULL,29/35] block: acquire AioContext in do_drive_del()

Message ID 1409329803-20744-30-git-send-email-stefanha@redhat.com
State New
Headers show

Commit Message

Stefan Hajnoczi Aug. 29, 2014, 4:29 p.m. UTC 
Make drive_del safe for dataplane where another thread may be running
the BlockDriverState's AioContext.

Note the assumption that AioContext's lifetime exceeds DriveInfo and
BlockDriverState.  We release AioContext after DriveInfo and
BlockDriverState are potentially freed.

This is clearly safe with the global AioContext but also with -object
iothread and implicit iothreads created by -device
virtio-blk-pci,x-data-plane=on (their lifetime is tied to DeviceState,
not BlockDriverState).

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 blockdev.c | 7 +++++++
 1 file changed, 7 insertions(+)
diff mbox

Patch

diff --git a/blockdev.c b/blockdev.c
index eeb414e..e37b068 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -1757,6 +1757,7 @@  int do_drive_del(Monitor *mon, const QDict *qdict, QObject **ret_data)
 {
     const char *id = qdict_get_str(qdict, "id");
     BlockDriverState *bs;
+    AioContext *aio_context;
     Error *local_err = NULL;
 
     bs = bdrv_find(id);
@@ -1764,9 +1765,14 @@  int do_drive_del(Monitor *mon, const QDict *qdict, QObject **ret_data)
         error_report("Device '%s' not found", id);
         return -1;
     }
+
+    aio_context = bdrv_get_aio_context(bs);
+    aio_context_acquire(aio_context);
+
     if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_DRIVE_DEL, &local_err)) {
         error_report("%s", error_get_pretty(local_err));
         error_free(local_err);
+        aio_context_release(aio_context);
         return -1;
     }
 
@@ -1790,6 +1796,7 @@  int do_drive_del(Monitor *mon, const QDict *qdict, QObject **ret_data)
         drive_del(drive_get_by_blockdev(bs));
     }
 
+    aio_context_release(aio_context);
     return 0;
 }