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CLEANUP: fd: use a union in fd_rm_from_fd_list() to shut aliasing warnings

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Enabling strict aliasing fails in fd.c when using the double-word CAS,
let's get rid of the (void**)(void*)&cur_list junk and use a union
instead. This way the compiler knows they do alias.
This commit is contained in:
Willy Tarreau 2020-02-25 09:25:53 +01:00
parent 105599c1ba
commit 2b9f0664d6
1 changed files with 14 additions and 10 deletions
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24
src/fd.c
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@ -179,7 +179,11 @@ done:
void fd_rm_from_fd_list(volatile struct fdlist *list, int fd, int off)
{
#if defined(HA_HAVE_CAS_DW) || defined(HA_CAS_IS_8B)
volatile struct fdlist_entry cur_list, next_list;
volatile union {
struct fdlist_entry ent;
uint64_t u64;
uint32_t u32[2];
} cur_list, next_list;
#endif
int old;
int new = -2;
@ -188,24 +192,24 @@ void fd_rm_from_fd_list(volatile struct fdlist *list, int fd, int off)
int last;
lock_self:
#if (defined(HA_CAS_IS_8B) || defined(HA_HAVE_CAS_DW))
next_list.next = next_list.prev = -2;
cur_list = *(volatile struct fdlist_entry *)(((char *)&fdtab[fd]) + off);
next_list.ent.next = next_list.ent.prev = -2;
cur_list.ent = *(volatile struct fdlist_entry *)(((char *)&fdtab[fd]) + off);
/* First, attempt to lock our own entries */
do {
/* The FD is not in the FD cache, give up */
if (unlikely(cur_list.next <= -3))
if (unlikely(cur_list.ent.next <= -3))
return;
if (unlikely(cur_list.prev == -2 || cur_list.next == -2))
if (unlikely(cur_list.ent.prev == -2 || cur_list.ent.next == -2))
goto lock_self;
} while (
#ifdef HA_CAS_IS_8B
unlikely(!_HA_ATOMIC_CAS(((void **)(void *)&_GET_NEXT(fd, off)), ((void **)(void *)&cur_list), (*(void **)(void *)&next_list))))
unlikely(!_HA_ATOMIC_CAS(((uint64_t *)&_GET_NEXT(fd, off)), (uint64_t *)&cur_list.u64, next_list.u64))
#else
unlikely(!_HA_ATOMIC_DWCAS(((void *)&_GET_NEXT(fd, off)), ((void *)&cur_list), ((void *)&next_list))))
unlikely(!_HA_ATOMIC_DWCAS(((long *)&_GET_NEXT(fd, off)), (uint32_t *)&cur_list.u32, &next_list.u32))
#endif
;
next = cur_list.next;
prev = cur_list.prev;
);
next = cur_list.ent.next;
prev = cur_list.ent.prev;
#else
lock_self_next: