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authorZhenzhong Duan <zhenzhong.duan@intel.com>2022-10-17 15:53:50 +0800
committerJuan Quintela <quintela@redhat.com>2023-02-06 19:22:57 +0100
commitddbe628c97c3a2d211c6d96383cb4063ac3ad0f9 (patch)
tree24b3525ac18877715b0c449304aa29ca14b234c2 /migration
parent6720c2b32725e6ac404f22851a0ecd0a71d0cbe2 (diff)
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multifd: Fix a race on reading MultiFDPages_t.block
In multifd_queue_page() MultiFDPages_t.block is checked twice. Between the two checks, MultiFDPages_t.block may be reset to NULL by multifd thread. This lead to the 2nd check always true then a redundant page submitted to multifd thread again. Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com> Reviewed-by: Juan Quintela <quintela@redhat.com> Signed-off-by: Juan Quintela <quintela@redhat.com>
Diffstat (limited to 'migration')
-rw-r--r--migration/multifd.c7
1 files changed, 5 insertions, 2 deletions
diff --git a/migration/multifd.c b/migration/multifd.c
index eeb4fb8..ad89293 100644
--- a/migration/multifd.c
+++ b/migration/multifd.c
@@ -442,6 +442,7 @@ static int multifd_send_pages(QEMUFile *f)
int multifd_queue_page(QEMUFile *f, RAMBlock *block, ram_addr_t offset)
{
MultiFDPages_t *pages = multifd_send_state->pages;
+ bool changed = false;
if (!pages->block) {
pages->block = block;
@@ -454,14 +455,16 @@ int multifd_queue_page(QEMUFile *f, RAMBlock *block, ram_addr_t offset)
if (pages->num < pages->allocated) {
return 1;
}
+ } else {
+ changed = true;
}
if (multifd_send_pages(f) < 0) {
return -1;
}
- if (pages->block != block) {
- return multifd_queue_page(f, block, offset);
+ if (changed) {
+ return multifd_queue_page(f, block, offset);
}
return 1;