From 2f4aefd320a8c3aeb739d59724c5c4dd6a995919 Mon Sep 17 00:00:00 2001 From: Ivan Ren Date: Thu, 29 Aug 2019 10:16:36 +0800 Subject: migration: multifd_send_thread always post p->sem_sync when error happen When encounter error, multifd_send_thread should always notify who pay attention to it before exit. Otherwise it may block migration_thread at multifd_send_sync_main forever. Error as follow: ------------------------------------------------------------------------------- (gdb) bt #0 0x00007f4d669dfa0b in do_futex_wait.constprop.1 () from /lib64/libpthread.so.0 #1 0x00007f4d669dfa9f in __new_sem_wait_slow.constprop.0 () from /lib64/libpthread.so.0 #2 0x00007f4d669dfb3b in sem_wait@@GLIBC_2.2.5 () from /lib64/libpthread.so.0 #3 0x0000562ccf0a5614 in qemu_sem_wait (sem=sem@entry=0x562cd1b698e8) at util/qemu-thread-posix.c:319 #4 0x0000562ccecb4752 in multifd_send_sync_main (rs=) at /qemu/migration/ram.c:1099 #5 0x0000562ccecb95f4 in ram_save_iterate (f=0x562cd0ecc000, opaque=) at /qemu/migration/ram.c:3550 #6 0x0000562ccef43c23 in qemu_savevm_state_iterate (f=0x562cd0ecc000, postcopy=false) at migration/savevm.c:1189 #7 0x0000562ccef3dcf3 in migration_iteration_run (s=0x562cd09fabf0) at migration/migration.c:3131 #8 migration_thread (opaque=opaque@entry=0x562cd09fabf0) at migration/migration.c:3258 #9 0x0000562ccf0a4c26 in qemu_thread_start (args=) at util/qemu-thread-posix.c:502 #10 0x00007f4d669d9e25 in start_thread () from /lib64/libpthread.so.0 #11 0x00007f4d6670635d in clone () from /lib64/libc.so.6 (gdb) f 4 #4 0x0000562ccecb4752 in multifd_send_sync_main (rs=) at /qemu/migration/ram.c:1099 1099 qemu_sem_wait(&p->sem_sync); (gdb) list 1094 } 1095 for (i = 0; i < migrate_multifd_channels(); i++) { 1096 MultiFDSendParams *p = &multifd_send_state->params[i]; 1097 1098 trace_multifd_send_sync_main_wait(p->id); 1099 qemu_sem_wait(&p->sem_sync); 1100 } 1101 trace_multifd_send_sync_main(multifd_send_state->packet_num); 1102 } 1103 (gdb) p i $1 = 0 (gdb) p multifd_send_state->params[0].pending_job $2 = 2 //It means the job before MULTIFD_FLAG_SYNC has already fail (gdb) p multifd_send_state->params[0].quit $3 = true Signed-off-by: Ivan Ren Message-Id: <1567044996-2362-1-git-send-email-ivanren@tencent.com> Reviewed-by: Juan Quintela Signed-off-by: Dr. David Alan Gilbert --- migration/ram.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/migration/ram.c b/migration/ram.c index b01a37e7ca..0047286b7e 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -1112,6 +1112,7 @@ static void *multifd_send_thread(void *opaque) rcu_register_thread(); if (multifd_send_initial_packet(p, &local_err) < 0) { + ret = -1; goto out; } /* initial packet */ @@ -1179,9 +1180,7 @@ out: * who pay attention to me. */ if (ret != 0) { - if (flags & MULTIFD_FLAG_SYNC) { - qemu_sem_post(&p->sem_sync); - } + qemu_sem_post(&p->sem_sync); qemu_sem_post(&multifd_send_state->channels_ready); } -- cgit v1.2.3-55-g7522