From: Pravin M Bathija <[email protected]> The VHOST_USER_REM_MEM_REG handler rejects messages carrying a file descriptor, but the vhost-user specification allows back-ends to accept one for compatibility with incorrect front-end implementations.
libblkio (v1.5.0) sends an fd with REM_MEM_REG because it shares a message helper with ADD_MEM_REG. This causes DPDK to drop the connection with: expect 0 FDs for request VHOST_USER_REM_MEM_REG, received 1 QEMU's libvhost-user reference back-end already tolerates this. The fix accepts the message and closes any unexpected fd without using it, conforming to the specification's compatibility clause. Tested with: - QEMU VM bring-up with add/remove memory regions via monitor - QEMU post-copy live migration between source and destination - SPDK vhost-blk with libblkio fio engine (write + md5 verify) - libblkio alloc-mem-region and map-mem-region unit tests (ADD/REM/ADD cycles against SPDK vhost-blk) Pravin M Bathija (1): vhost: tolerate file descriptor in REM_MEM_REG msg lib/vhost/vhost_user.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) -- 2.43.0
