49b44549ac
On restart, we were scheduling a BH to process queued requests, which would run before starting up the data plane, leading to those requests being assigned and started on coroutines on the main context. This could cause requests to be wrongly processed in parallel from different threads (the main thread and the iothread managing the data plane), potentially leading to multiple issues. For example, stopping and resuming a VM multiple times while the guest is generating I/O on a virtio_blk device can trigger a crash with a stack tracing looking like this one: <------> Thread 2 (Thread 0x7ff736765700 (LWP 1062503)): #0 0x00005567a13b99d6 in iov_memset (iov=0x6563617073206f4e, iov_cnt=1717922848, offset=516096, fillc=0, bytes=7018105756081554803) at util/iov.c:69 #1 0x00005567a13bab73 in qemu_iovec_memset (qiov=0x7ff73ec99748, offset=516096, fillc=0, bytes=7018105756081554803) at util/iov.c:530 #2 0x00005567a12f411c in qemu_laio_process_completion (laiocb=0x7ff6512ee6c0) at block/linux-aio.c:86 #3 0x00005567a12f42ff in qemu_laio_process_completions (s=0x7ff7182e8420) at block/linux-aio.c:217 #4 0x00005567a12f480d in ioq_submit (s=0x7ff7182e8420) at block/linux-aio.c:323 #5 0x00005567a12f43d9 in qemu_laio_process_completions_and_submit (s=0x7ff7182e8420) at block/linux-aio.c:236 #6 0x00005567a12f44c2 in qemu_laio_poll_cb (opaque=0x7ff7182e8430) at block/linux-aio.c:267 #7 0x00005567a13aed83 in run_poll_handlers_once (ctx=0x5567a2b58c70, timeout=0x7ff7367645f8) at util/aio-posix.c:520 #8 0x00005567a13aee9f in run_poll_handlers (ctx=0x5567a2b58c70, max_ns=16000, timeout=0x7ff7367645f8) at util/aio-posix.c:562 #9 0x00005567a13aefde in try_poll_mode (ctx=0x5567a2b58c70, timeout=0x7ff7367645f8) at util/aio-posix.c:597 #10 0x00005567a13af115 in aio_poll (ctx=0x5567a2b58c70, blocking=true) at util/aio-posix.c:639 #11 0x00005567a109acca in iothread_run (opaque=0x5567a2b29760) at iothread.c:75 #12 0x00005567a13b2790 in qemu_thread_start (args=0x5567a2b694c0) at util/qemu-thread-posix.c:519 #13 0x00007ff73eedf2de in start_thread () at /lib64/libpthread.so.0 #14 0x00007ff73ec10e83 in clone () at /lib64/libc.so.6 Thread 1 (Thread 0x7ff743986f00 (LWP 1062500)): #0 0x00005567a13b99d6 in iov_memset (iov=0x6563617073206f4e, iov_cnt=1717922848, offset=516096, fillc=0, bytes=7018105756081554803) at util/iov.c:69 #1 0x00005567a13bab73 in qemu_iovec_memset (qiov=0x7ff73ec99748, offset=516096, fillc=0, bytes=7018105756081554803) at util/iov.c:530 #2 0x00005567a12f411c in qemu_laio_process_completion (laiocb=0x7ff6512ee6c0) at block/linux-aio.c:86 #3 0x00005567a12f42ff in qemu_laio_process_completions (s=0x7ff7182e8420) at block/linux-aio.c:217 #4 0x00005567a12f480d in ioq_submit (s=0x7ff7182e8420) at block/linux-aio.c:323 #5 0x00005567a12f4a2f in laio_do_submit (fd=19, laiocb=0x7ff5f4ff9ae0, offset=472363008, type=2) at block/linux-aio.c:375 #6 0x00005567a12f4af2 in laio_co_submit (bs=0x5567a2b8c460, s=0x7ff7182e8420, fd=19, offset=472363008, qiov=0x7ff5f4ff9ca0, type=2) at block/linux-aio.c:394 #7 0x00005567a12f1803 in raw_co_prw (bs=0x5567a2b8c460, offset=472363008, bytes=20480, qiov=0x7ff5f4ff9ca0, type=2) at block/file-posix.c:1892 #8 0x00005567a12f1941 in raw_co_pwritev (bs=0x5567a2b8c460, offset=472363008, bytes=20480, qiov=0x7ff5f4ff9ca0, flags=0) at block/file-posix.c:1925 #9 0x00005567a12fe3e1 in bdrv_driver_pwritev (bs=0x5567a2b8c460, offset=472363008, bytes=20480, qiov=0x7ff5f4ff9ca0, qiov_offset=0, flags=0) at block/io.c:1183 #10 0x00005567a1300340 in bdrv_aligned_pwritev (child=0x5567a2b5b070, req=0x7ff5f4ff9db0, offset=472363008, bytes=20480, align=512, qiov=0x7ff72c0425b8, qiov_offset=0, flags=0) at block/io.c:1980 #11 0x00005567a1300b29 in bdrv_co_pwritev_part (child=0x5567a2b5b070, offset=472363008, bytes=20480, qiov=0x7ff72c0425b8, qiov_offset=0, flags=0) at block/io.c:2137 #12 0x00005567a12baba1 in qcow2_co_pwritev_task (bs=0x5567a2b92740, file_cluster_offset=472317952, offset=487305216, bytes=20480, qiov=0x7ff72c0425b8, qiov_offset=0, l2meta=0x0) at block/qcow2.c:2444 #13 0x00005567a12bacdb in qcow2_co_pwritev_task_entry (task=0x5567a2b48540) at block/qcow2.c:2475 #14 0x00005567a13167d8 in aio_task_co (opaque=0x5567a2b48540) at block/aio_task.c:45 #15 0x00005567a13cf00c in coroutine_trampoline (i0=738245600, i1=32759) at util/coroutine-ucontext.c:115 #16 0x00007ff73eb622e0 in __start_context () at /lib64/libc.so.6 #17 0x00007ff6626f1350 in () #18 0x0000000000000000 in () <------> This is also known to cause crashes with this message (assertion failed): aio_co_schedule: Co-routine was already scheduled in 'aio_co_schedule' RHBZ: https://bugzilla.redhat.com/show_bug.cgi?id=1812765 Signed-off-by: Sergio Lopez <slp@redhat.com> Message-Id: <20200603093240.40489-3-slp@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
92 lines
2.1 KiB
C
92 lines
2.1 KiB
C
/*
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* Virtio Block Device
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*
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* Copyright IBM, Corp. 2007
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*
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* Authors:
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* Anthony Liguori <aliguori@us.ibm.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2. See
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* the COPYING file in the top-level directory.
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*
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*/
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#ifndef QEMU_VIRTIO_BLK_H
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#define QEMU_VIRTIO_BLK_H
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#include "standard-headers/linux/virtio_blk.h"
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#include "hw/virtio/virtio.h"
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#include "hw/block/block.h"
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#include "sysemu/iothread.h"
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#include "sysemu/block-backend.h"
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#define TYPE_VIRTIO_BLK "virtio-blk-device"
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#define VIRTIO_BLK(obj) \
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OBJECT_CHECK(VirtIOBlock, (obj), TYPE_VIRTIO_BLK)
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/* This is the last element of the write scatter-gather list */
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struct virtio_blk_inhdr
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{
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unsigned char status;
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};
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struct VirtIOBlkConf
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{
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BlockConf conf;
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IOThread *iothread;
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char *serial;
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uint32_t request_merging;
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uint16_t num_queues;
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uint16_t queue_size;
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bool seg_max_adjust;
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uint32_t max_discard_sectors;
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uint32_t max_write_zeroes_sectors;
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bool x_enable_wce_if_config_wce;
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};
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struct VirtIOBlockDataPlane;
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struct VirtIOBlockReq;
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typedef struct VirtIOBlock {
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VirtIODevice parent_obj;
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BlockBackend *blk;
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void *rq;
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QEMUBH *bh;
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VirtIOBlkConf conf;
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unsigned short sector_mask;
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bool original_wce;
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VMChangeStateEntry *change;
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bool dataplane_disabled;
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bool dataplane_started;
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struct VirtIOBlockDataPlane *dataplane;
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uint64_t host_features;
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size_t config_size;
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} VirtIOBlock;
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typedef struct VirtIOBlockReq {
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VirtQueueElement elem;
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int64_t sector_num;
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VirtIOBlock *dev;
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VirtQueue *vq;
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struct virtio_blk_inhdr *in;
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struct virtio_blk_outhdr out;
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QEMUIOVector qiov;
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size_t in_len;
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struct VirtIOBlockReq *next;
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struct VirtIOBlockReq *mr_next;
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BlockAcctCookie acct;
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} VirtIOBlockReq;
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#define VIRTIO_BLK_MAX_MERGE_REQS 32
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typedef struct MultiReqBuffer {
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VirtIOBlockReq *reqs[VIRTIO_BLK_MAX_MERGE_REQS];
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unsigned int num_reqs;
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bool is_write;
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} MultiReqBuffer;
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bool virtio_blk_handle_vq(VirtIOBlock *s, VirtQueue *vq);
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void virtio_blk_process_queued_requests(VirtIOBlock *s, bool is_bh);
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#endif
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