40f4a21895
The following scenario leads to an assertion failure in qio_channel_yield(): 1. Request coroutine calls qio_channel_yield() successfully when sending would block on the socket. It is now yielded. 2. nbd_read_reply_entry() calls nbd_recv_coroutines_enter_all() because nbd_receive_reply() failed. 3. Request coroutine is entered and returns from qio_channel_yield(). Note that the socket fd handler has not fired yet so ioc->write_coroutine is still set. 4. Request coroutine attempts to send the request body with nbd_rwv() but the socket would still block. qio_channel_yield() is called again and assert(!ioc->write_coroutine) is hit. The problem is that nbd_read_reply_entry() does not distinguish between request coroutines that are waiting to receive a reply and those that are not. This patch adds a per-request bool receiving flag so nbd_read_reply_entry() can avoid spurious aio_wake() calls. Reported-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Message-Id: <20170822125113.5025-1-stefanha@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Tested-by: Eric Blake <eblake@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Eric Blake <eblake@redhat.com>
64 lines
2 KiB
C
64 lines
2 KiB
C
#ifndef NBD_CLIENT_H
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#define NBD_CLIENT_H
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#include "qemu-common.h"
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#include "block/nbd.h"
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#include "block/block_int.h"
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#include "io/channel-socket.h"
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/* #define DEBUG_NBD */
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#if defined(DEBUG_NBD)
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#define logout(fmt, ...) \
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fprintf(stderr, "nbd\t%-24s" fmt, __func__, ##__VA_ARGS__)
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#else
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#define logout(fmt, ...) ((void)0)
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#endif
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#define MAX_NBD_REQUESTS 16
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typedef struct {
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Coroutine *coroutine;
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bool receiving; /* waiting for read_reply_co? */
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} NBDClientRequest;
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typedef struct NBDClientSession {
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QIOChannelSocket *sioc; /* The master data channel */
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QIOChannel *ioc; /* The current I/O channel which may differ (eg TLS) */
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NBDExportInfo info;
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CoMutex send_mutex;
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CoQueue free_sema;
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Coroutine *read_reply_co;
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int in_flight;
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NBDClientRequest requests[MAX_NBD_REQUESTS];
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NBDReply reply;
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bool quit;
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} NBDClientSession;
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NBDClientSession *nbd_get_client_session(BlockDriverState *bs);
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int nbd_client_init(BlockDriverState *bs,
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QIOChannelSocket *sock,
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const char *export_name,
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QCryptoTLSCreds *tlscreds,
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const char *hostname,
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Error **errp);
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void nbd_client_close(BlockDriverState *bs);
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int nbd_client_co_pdiscard(BlockDriverState *bs, int64_t offset, int bytes);
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int nbd_client_co_flush(BlockDriverState *bs);
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int nbd_client_co_pwritev(BlockDriverState *bs, uint64_t offset,
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uint64_t bytes, QEMUIOVector *qiov, int flags);
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int nbd_client_co_pwrite_zeroes(BlockDriverState *bs, int64_t offset,
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int bytes, BdrvRequestFlags flags);
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int nbd_client_co_preadv(BlockDriverState *bs, uint64_t offset,
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uint64_t bytes, QEMUIOVector *qiov, int flags);
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void nbd_client_detach_aio_context(BlockDriverState *bs);
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void nbd_client_attach_aio_context(BlockDriverState *bs,
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AioContext *new_context);
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#endif /* NBD_CLIENT_H */
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