diff options
| -rw-r--r-- | sys/kern/uipc_mbuf.c | 10 | ||||
| -rw-r--r-- | sys/sys/mbuf.h | 2 |
2 files changed, 5 insertions, 7 deletions
diff --git a/sys/kern/uipc_mbuf.c b/sys/kern/uipc_mbuf.c index 1f6069e..5e65572 100644 --- a/sys/kern/uipc_mbuf.c +++ b/sys/kern/uipc_mbuf.c @@ -199,7 +199,7 @@ m_extadd(struct mbuf *mb, caddr_t buf, u_int size, ref_cnt = (u_int *)uma_find_refcnt(zone_clust, mb->m_ext.ext_buf); else if (type == EXT_EXTREF) - ref_cnt = mb->m_ext.ref_cnt; + ref_cnt = __DEVOLATILE(u_int *, mb->m_ext.ref_cnt); mb->m_ext.ref_cnt = (ref_cnt == NULL) ? malloc(sizeof(u_int), M_MBUF, M_NOWAIT) : (u_int *)ref_cnt; if (mb->m_ext.ref_cnt != NULL) { @@ -234,12 +234,9 @@ mb_free_ext(struct mbuf *m) * This is tricky. We need to make sure to decrement the * refcount in a safe way but to also clean up if we're the * last reference. This method seems to do it without race. - * The volatile cast is required to emit the proper load - * instructions. Otherwise gcc will optimize the read outside - * of the while loop. */ while (dofree == 0) { - cnt = *(volatile u_int *)(m->m_ext.ref_cnt); + cnt = *(m->m_ext.ref_cnt); if (atomic_cmpset_int(m->m_ext.ref_cnt, cnt, cnt - 1)) { if (cnt == 1) dofree = 1; @@ -262,7 +259,8 @@ mb_free_ext(struct mbuf *m) m->m_ext.ext_args); if (m->m_ext.ext_type != EXT_EXTREF) { if (m->m_ext.ref_cnt != NULL) - free(m->m_ext.ref_cnt, M_MBUF); + free(__DEVOLATILE(u_int *, + m->m_ext.ref_cnt), M_MBUF); m->m_ext.ref_cnt = NULL; } m->m_ext.ext_buf = NULL; diff --git a/sys/sys/mbuf.h b/sys/sys/mbuf.h index 1621fa7..0703916 100644 --- a/sys/sys/mbuf.h +++ b/sys/sys/mbuf.h @@ -122,7 +122,7 @@ struct m_ext { (void *, void *); void *ext_args; /* optional argument pointer */ u_int ext_size; /* size of buffer, for ext_free */ - u_int *ref_cnt; /* pointer to ref count info */ + volatile u_int *ref_cnt; /* pointer to ref count info */ int ext_type; /* type of external storage */ }; |
