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66 lines
3.3 KiB
66 lines
3.3 KiB
commit cee000f97c9300dbbae50118838c6d3e8d5eb9cf
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Author: Willy Tarreau <w@1wt.eu>
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Date: Thu Feb 28 11:14:22 2019 +0100
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BUG/MEDIUM: list: add missing store barriers when updating elements and head
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Commit a8434ec14 ("MINOR: lists: Implement locked variations.")
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introduced locked lists which use the elements pointers as locks
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for concurrent operations. Under heavy stress the lists occasionally
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fail. The cause is a missing barrier at some points when updating
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the list element and the head : nothing prevents the compiler (or
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CPU) from updating the list head first before updating the element,
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making another thread jump to a wrong location. This patch simply
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adds the missing barriers before these two opeations.
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This will have to be backported if the commit above is backported.
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(cherry picked from commit 690d2ad4d207da5c8821b84ab467090bd515eedf)
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Signed-off-by: Willy Tarreau <w@1wt.eu>
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(cherry picked from commit c2aa5cb8b8ff3af27f1a962541e53f792745bc4a)
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Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
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diff --git a/include/common/mini-clist.h b/include/common/mini-clist.h
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index 51c61051..92a995c9 100644
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--- a/include/common/mini-clist.h
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+++ b/include/common/mini-clist.h
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@@ -189,6 +189,7 @@ struct cond_wordlist {
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} \
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(el)->n = n; \
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(el)->p = p; \
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+ __ha_barrier_store(); \
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n->p = (el); \
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__ha_barrier_store(); \
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p->n = (el); \
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@@ -214,6 +215,7 @@ struct cond_wordlist {
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} \
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(el)->n = n; \
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(el)->p = p; \
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+ __ha_barrier_store(); \
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n->p = (el); \
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__ha_barrier_store(); \
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p->n = (el); \
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@@ -276,6 +278,7 @@ struct cond_wordlist {
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continue; \
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if (n == (lh)) { \
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(lh)->n = lh; \
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+ __ha_barrier_store(); \
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_ret = NULL; \
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break; \
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} \
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@@ -288,6 +291,7 @@ struct cond_wordlist {
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n2 = HA_ATOMIC_XCHG(&n->n, LLIST_BUSY); \
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if (n2 == LLIST_BUSY) { \
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n->p = p; \
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+ __ha_barrier_store(); \
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(lh)->n = n; \
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__ha_barrier_store(); \
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continue; \
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@@ -296,6 +300,7 @@ struct cond_wordlist {
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if (p2 == LLIST_BUSY) { \
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n->n = n2; \
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n->p = p; \
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+ __ha_barrier_store(); \
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(lh)->n = n; \
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__ha_barrier_store(); \
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continue; \
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