BUG/MEDIUM: threads: fix the double CAS implementation for ARMv7

Commit f61f0cb ("MINOR: threads: Introduce double-width CAS on x86_64
and arm.") introduced the double CAS. But the ARMv7 version is bogus,
it uses the value of the pointers instead of dereferencing them. When
lucky, it simply doesn't build due to impossible registers combinations.
Otherwise it will immediately crash at run time when facing traffic.

No backport is needed, this bug was introduced in 1.9-dev.
This commit is contained in:
Willy Tarreau 2018-02-14 14:16:28 +01:00
parent 1ff9104117
commit 41ccb194d1

View File

@ -780,7 +780,7 @@ __ha_barrier_full(void)
__asm __volatile("dmb" ::: "memory");
}
static __inline int __ha_cas_dw(void *target, void *compare, void *set)
static __inline int __ha_cas_dw(void *target, void *compare, const void *set)
{
uint64_t previous;
int tmp;
@ -794,7 +794,7 @@ static __inline int __ha_cas_dw(void *target, void *compare, void *set)
"cmpeq %1, #1;"
"beq 1b;"
: "=&r" (previous), "=&r" (tmp)
: "r" (compare), "r" (set), "r" (target)
: "r" (*(uint64_t *)compare), "r" (*(uint64_t *)set), "r" (target)
: "memory", "cc");
tmp = (previous == *(uint64_t *)compare);
*(uint64_t *)compare = previous;